CN101009214B - Methods of fabricating nanostructures and nanowires and devices fabricated therefrom - Google Patents

Methods of fabricating nanostructures and nanowires and devices fabricated therefrom Download PDF

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CN101009214B
CN101009214B CN2007100082590A CN200710008259A CN101009214B CN 101009214 B CN101009214 B CN 101009214B CN 2007100082590 A CN2007100082590 A CN 2007100082590A CN 200710008259 A CN200710008259 A CN 200710008259A CN 101009214 B CN101009214 B CN 101009214B
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nano wire
laser
nano
wire
notion
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CN101009214A (en
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A·马亚姆达
A·沙科里
T·D·桑德斯
P·杨
S·S·毛
R·E·拉索
H·费克
H·金德
E·R·韦伯
M·黄
H·严
Y·吴
R·范
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University of California
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/01—Chemical elements
    • H01L2924/01014—Silicon [Si]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/12—Passive devices, e.g. 2 terminal devices
    • H01L2924/1204—Optical Diode
    • H01L2924/12041—LED

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Abstract

One-dimensional nanostructures having uniform diameters of less than approximately 200 nm. These inventive nanostructures, which we refer to as ''nanowires'', include single-crystalline homostructuresas well as heterostructures of at least two single-crystalline materials having different chemical compositions. Because single-crystalline materials are used to form the heterostructure, the resultant heterostructure will be single-crystalline as well. The nanowire heterostructures are generally based on a semiconducting wire wherein the doping and composition are controlled in either the longitudinal or radial directions, or in both directions, to yield a wire that comprises different materials. Examples of resulting nanowire heterostructures include a longitudinal heterostructure nanowire(LOHN) and a coaxial heterostructure nanowire (COHN).

Description

The manufacture method of nanostructure and nano wire reaches the device by its manufacturing
The cross reference of related application
The application requires in the U.S. Provisional Application series number 60/280676 of application on March 30 calendar year 2001, in the priority of the U.S. Provisional Application series number 60/349206 of application on January 15th, 2002, and it is for reference to quote these two pieces of documents here as proof.
State about the sponsor of alliance investigation or development
The grant number that the grant number that the present invention is is No.DE-AC03-76SF00098 in the contract number by Deparment of Energy signing, authorized by National Science Foundation is DMR-0092086, authorized by National Science Foundation be under the CTS-0103609 by government support done.Government has certain right in the present invention.
Reference computers program appendix
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Technical field
The present invention relates generally to nanostructure, being particularly related to what have diameter along bobbin is nano wire (nanowire) structure of crystal basically, it is presenting on the diameter on the maximum cross section that changes being less than about quantitative changeization of 10%, and also has the diameter less than about 200nm.Nano thread structure can form homostyructure, heterostructure and combination thereof.
Background technology
As shown in Figure 1, the ability of switching energy has produced the basis of any modern economy effectively between multi-form (for example heat, electricity, machinery and optics), and is the most generally acknowledged mark that develops in science and engineering science.For example, optoelectronics is handled the conversion between optics and the electricity form, and it has placed the basis of a lot of aspects that are used for modern information technologies.Conversion between heat energy and the electric energy is the characteristics of energy economy, and minor modifications is wherein arranged on efficient, and conversion method may have economic impact to saving money, energy reserve and environment.Equally, the electrochemical energy conversion is in the core of a lot of modern machines and transducer, has been found that they are widely used technically.Given its importance is whether inquiry nanometer scale science and engineering science can take on any role substantially in power conversion.Very clear, in view of seeking to minimize and improve device efficiency continuously, nanometer scale device can be taken on the role in power conversion.Correspondingly, the wide power spectrum that needs a kind of high performance converters part on one-dimensional inorganic nanostructure or nano wire basis.The present invention has satisfied these needs and other needs, and has overcome the deficiency that exists in the conventional device.
Summary of the invention
The present invention relates generally to be essentially the nanostructure of crystal, be particularly related to the one-dimensional nano structure that has along the diameter of the longitudinal axis, this nanostructure can not change on the cross section that the maximum that presents on the diameter changes and surpasses approximately 10%, and has the diameter less than about 200nm in the position of maximum gauge.We are referred to as " nano wire " nanostructure of these inventions, preferably include basically the monocrystalline homostyructure and form at least a crystalline material basically of interface or knot and a kind of heterostructure of other material betwixt.Also can comprise the combination of homostyructure and heterostructure according to heterostructure of the present invention.Be used to form at the material that is crystal basically under the situation of heterostructure, the heterostructure that obtains will be essentially crystal.In addition, can have various shape of cross sections, include but not limited to circle, square, rectangle and hexagon according to nano wire of the present invention.
Heterostructure can be formed with any amount of section, and is vertical and axial, wherein adjacent segment be essentially crystal or wherein be basically crystal the section adjacent with the material that is not crystal basically.Generally based on the semiconductive line, wherein dopant and composition are vertically or radially or in the both direction Be Controlled, so that produce the line that comprises different materials according to a lot of nano wire hetero structures of the present invention.The section of heterostructure can be various materials, for example comprises the semi-conducting material of doping or intrinsic, and setting has the various semiconductor device of knot as pn, pnp, npn, pin, pip etc. with formation.
By other example, according to the solution of the present invention, when nano wire when vertically watching can comprise different materials, as can be different materials alternately or constant time range or at least two sections multistage nano wires that comprise different materials wherein.We are called vertical heterogeneous structural nano line (LOHN) with this structure.Example will be LOHN, and wherein adjacent segment has different chemical composition, as Si and SiGe.
According to another aspect of the present invention, nano wire will be the coaxial type structure, comprise the core of first material that is surrounded by the sleeve pipe of second material.We are called coaxial heterojunction structure nano wire (COHN) with this structure.Qualification is the acutance that knot between the material of crystal presents height usually according to the composition of nano wire hetero structure of the present invention basically.For example, according to the present invention, the interface between these materials can be made for the acutance of an about atomic layer to about 20nm.Yet, because can comprise according to heterostructure of the present invention on vertical, coaxial or this both direction a plurality of sections therefore can also forming such heterostructure, the some of them knot presents high sharpness, other knot does not present high sharpness, and this depends on application-specific and needs.In addition, the composition that forms the material of adjacent segment not only can be sharp keen or mild, and forms the doping of material of the section of heterostructure by control, the sharp keen or mild dopant transition between can the section of having.
In certain embodiments of the present invention, nanostructure of the present invention is got rid of the structure that comprises carbon nano-tube especially and/or is comprised the structure that is commonly referred to " whisker " or " nano whisker ".
Should be understood that and adopt aforementioned structure of the present invention can realize various structures, wherein certain structures has been introduced in front.By further example, but do not limit, these structures can comprise unijunction and many knot LOHN, unijunctions and tie COHN, LOHN more and the combination of the combination of COHN structure, two-terminal structure, N＞2 terminal structures, heterostructure and homostyructure, have one or more electrodes (also will be overall heterostructure) homostyructure, have one or more electrodes heterostructure, have insulator homostyructure, have insulator heterostructure, or the like.It is also to be understood that the interface between nano wire and the terminal constitutes heterojunction.Adopt these structures and structure can make various devices, include but not limited to the photon band gap device, electronics (for example is limited in quantum dot in the specific region, thermoelectric device, solid-state refrigerator and engine), photonic device (for example nano laser), nano-electromechanical (MEM) device (dynamo-electric exciter and transducer), various forms of power conversion device, comprise that light for example is to mechanical energy or heat energy conversion and other device to light.
According to another aspect of the present invention, developed the technology that is used to make nano wire.Particularly, if the diameter of (within the populationh) distributes and to be less than or to equal about 50%rms in colony, more preferably less than or equal 20%, most preferably be less than 10%rms, this scheme of the present invention comprises the technology that is used to make a large amount of nano wire hetero structures with single basically dispersed and distributed diameter.Another program of the present invention comprises the technology that is used to form a large amount of nano wires with single basically dispersed and distributed length.A large amount of nano wires are considered to have the single dispersed and distributed length in distribution of lengths, and wherein quantity is less than or equals 20%rms, more preferably less than or equal 10%, more preferably less than or equal 5%, most preferably be less than or equal 1%.Further scheme of the present invention comprises the design that is used for nano wire, allows to make in batches in a large number.Another program of the present invention comprises the Laser Devices that can be formed by heterostructure or homostyructure.
1, a kind of method of making nano wire comprises: dissolving first gas reactant in catalyst liquid, grow first section then; With dissolving second gas reactant in described catalyst liquid, the section different of growing then with second composition of described first section connection; Wherein said section have one of at least a diameter uniformly basically less than about 200nm.
2, according to the method for notion 1: wherein form the different liquid alloy of composition by every kind of described gas reactant and described catalyst liquid; Wherein each described section is the saturated formation of material by described liquid alloy and described corresponding gas reactant.
3, according to the method for notion 1: wherein said first and second gas reactants comprise respectively the steam that the laser ablation by first and second growth material produces.
4, according to the method for notion 3, wherein said first and second gas reactants also comprise vector gas.
5, according to the method for notion 1: wherein said second gas reactant comprises the steam that the laser ablation by growth material produces; With wherein said second section combination that is included in the described material in described first and second gas reactants.
6, according to the method for notion 1, wherein said catalyst liquid is formed by the prefabricated metal colloid.
7, according to the method for notion 6, wherein said metallic colloid is to have the diameter metallic colloid group's of single dispersed and distributed a part basically.
8, a kind of method of making nano wire comprises: dissolved gas reactant in catalyst liquid, grow first section then; With described first section and form second section with second kind of different coated materials of composition; Wherein said section have one of at least a diameter uniformly basically less than about 200nm.
9, according to the method for notion 8; Wherein form liquid alloy by described gas reactant and described catalyst liquid; With wherein said first section be the saturated formation of the described liquid alloy of material by having described gas reactant.
10, according to the method for notion 8, wherein said catalyst liquid is formed by the prefabricated metal colloid.
11, according to the method for notion 10, wherein said metallic colloid is to have the diameter metallic colloid group's of single dispersed and distributed a part basically.
12, a kind of method of making nano wire comprises: by dissolving first gas reactant in catalyst liquid, and first material of growing then, thus form first section; By dissolving second gas reactant in described catalyst liquid, growth is connected to second material of described first material then, is connected to described first section second section thereby form; Wherein each described section is the saturated formation of the described liquid alloy of material by having described corresponding gas reactant; With at least one at least a portion of described section of the 3rd coated materials, so that form the 3rd section; At least two kinds of wherein said material is that composition is different; Has diameter uniformly basically with at least one of wherein said section less than about 200nm.
13, a kind of method of making nano wire comprises: dissolving first gas reactant in catalyst liquid, first of growth material section then; Dissolving second gas reactant in described catalyst liquid, growing then is connected to second section of described first section material; With dissolving the 3rd gas reactant in described catalyst liquid, growing then is connected to the 3rd section of described second section material; Wherein said first, second and the 3rd section are vertical adjacent; Wherein said second section is arranged between described first and the 3rd section; At least two materials that comprise that composition is different of wherein said section; Has diameter uniformly basically with at least one of wherein said section less than about 200nm.
14, according to the method for notion 13: at least two kinds of wherein said gas reactant is identical; Comprise same material with wherein said section at least two.
15, according to the method for notion 13: wherein liquid alloy is formed by every kind of described gas reactant and described catalyst liquid; Wherein each described nanowire segment is the saturated formation of the described liquid alloy of material by having described corresponding gas reactant.
16, according to the method for notion 13: wherein said gas reactant at least a comprises the steam that the laser ablation by growth material produces; Be included in described laser with at least one of wherein said nanowire segment and produce the material in the steam and the combination of at least a other gas reactant.
17, a kind of method of making nano wire hetero structure comprises: dissolving first gas reactant in catalyst liquid, first section of first material of growing then; With dissolving second gas reactant in described catalyst liquid, second section of different second material of the vertical adjacent composition of growth and described first material then; Wherein said second gas reactant comprises the steam by the laser ablation generation of growth material; Wherein the different liquid alloy of composition is formed by every kind of described gas reactant and described catalyst liquid; The wherein saturated formation of the described liquid alloy of each the described section material by having described corresponding gas reactant; Wherein said second material comprises the combination of the described material in described first and second gas reactants; At least one of wherein said section has the uniform basically diameter less than about 200nm.
18, a kind of method of making nano wire comprises: dissolving first gas reactant in catalyst liquid, first section of first material of growing then; Continuous laser ablation growth material forms second gas reactant thus under the situation that has described first gas reactant; Described second gas reactant of dissolving in described catalyst liquid, second section of different second material of the vertical adjacent composition of growth and described first material then; Wherein said second material comprises the combination of the material in described first and second gas reactants; At least one of wherein said section has the uniform basically diameter less than about 200nm.
19, according to the method for notion 18: wherein the different liquid alloy of composition is formed by every kind of described gas reactant and described catalyst liquid; Wherein each described section is the saturated formation of the described liquid alloy of material by having described corresponding gas reactant.
20, a kind of method of making the doped semiconductor superlattice nano line comprises: introduce gas reactant in the reative cell of the stove that contains the substrate that is applied by reacting metal; Described reative cell is heated to uniform temperature, makes that the described molten metal on the described substrate changes at least one drop; Described gas reactant is dissolved in the described drop, till saturated, form nucleus therein and grow first section; With dopant and described gas reactant are dissolved in the described drop, till saturated, take place on described first section wherein that nucleus forms and second section of grow doping; At least one of wherein said section has the uniform basically diameter less than about 200nm.
21, according to the method for notion 20, wherein said substrate comprises and is selected from the element of being made up of III family and IV family element basically.
22, according to the method for notion 20, wherein said metal comprises gold.
23, according to the method for notion 22, wherein said gold comprises collaurum.
24, according to the method for notion 20, wherein said substrate comprises silicon; And wherein said metal comprises gold.
25, according to the method for notion 20, wherein said stove comprises quartzy stove reaction tube.
26, according to the method for notion 20, wherein said gas reactant comprises H 2And SiCl 4Mixture.
27, a kind of method of making Si/SiGe superlattice nano line heterostructure comprises:
Deposit Au on substrate;
Described substrate is placed in the quartzy stove reaction tube;
With H 2And SiCl 4Gas reaction mixture be incorporated in the described reaction tube;
Described reaction tube is heated to uniform temperature, makes described Au be liquefied as the Au-Si alloy liquid droplet of at least one nano-scale; With
Described gas reactant is dissolved in the described drop till saturated, the nucleation and the growth of Si section take place therein;
During described Si growth technique, by producing Ge steam with laser ablation Ge target;
The nucleation and the growth of SiGe section in described Au-Si alloy liquid droplet, till saturated, are wherein taken place in Ge and Si deposition of materials on described Si section;
At least one of wherein said section has the uniform basically diameter less than about 200nm.
28, according to the method for notion 27, also comprise:
Turn on and off to pulsation laser;
Wherein form the Si/SiGe superlattice in one one mode.
29, according to the method for notion 27, wherein said substrate comprises the element that is selected from III family and IV family basically.
30, according to the method for notion 27, wherein said gold comprises collaurum.
31, according to the method for notion 27, wherein said substrate comprises silicon.
32, according to the method for notion 1,8,12,13,17,18,20 or 27, at least one the diameter that wherein has less than described section of the diameter of about 200nm can not change about more than 10% on described section length.
33, according to the method for notion 1,8,12,13,17,18,20 or 27, wherein said nano wire carries out the transition to described second section from described first section on from an about atomic layer to the distance of about 20nm.
34, according to the method for notion 33, wherein begin on one point to described second section transition to described second section transition from described first section, described there first section composition has been reduced at about 99% of the described first section composition at described first section center.
35, according to the method for notion 1,8,12,13,17,18,20 or 27, at least one of wherein said section comprises it being the material of crystal basically.
36, according to the method for notion 35, wherein said is that the material of crystal is monocrystalline basically basically.
37, according to the method for notion 1,8,12,13,17,18,20 or 27, at least one of wherein said section comprises semi-conducting material.
38,, also comprise at least one of described section of doping according to the method for notion 1,8,12,13,17,18,20 or 27.
39, according to the method for notion 1,8,12,13,17,18,20 or 27, wherein have less than described section of the diameter of about 200nm described at least one have the diameter in about 50nm scope at about 5nm.
40, according to the method for notion 1,8,12,13,17,18,20 or 27, wherein said second section with described first section vertical adjacent.
41, according to the method for notion 1,8,12,13,17,18,20 or 27, wherein said second section with described first section coaxial adjacent.
42, according to the method for notion 1,8,12,13,17,18,20 or 27, also comprise mix described first and second sections to form p-n junction.
43, according to the method for notion 42, wherein said nano wire comprises semiconductor device.
44, according to the method for notion 1,8,12,13,17,18,20 or 27, also comprise mix described section described one to form the p-i knot.
45, according to the method for notion 44, wherein said nano wire comprises semiconductor device.
46, according to the method for notion 1,8,12,13,17,18,20 or 27, also comprise mix described section described one to form the i-n knot.
47, according to the method for notion 46, wherein said nano wire comprises semiconductor device.
48,, also comprise electrode is electrically coupled at least one of described section according to the method for notion 1,8,12,13,17,18,20 or 27.
49, according to the method for notion 1,8,12,13,17,18,20 or 27, at least one of wherein said section comprises element and ternary material and the quaternary material that is selected from II family, III family, IV family, V family and VI family element basically.
50,, also be included in embedding described section at least one in the polymeric matrix according to the method for notion 1,8,12,13,17,18,20 or 27.
51,, also be included in deposit sleeve pipe on described section at least one the part according to the method for notion 1,8,12,13,17,18,20 or 27.
52, according to the method for notion 51, wherein said sleeve pipe comprises non-crystalline material.
53, according to the method for notion 51, wherein said sleeve pipe comprises it being the material of crystal basically.
54, according to the method for notion 53, wherein said is that the material of crystal is monocrystalline basically basically.
55, according to the method for notion 1,8,12,13,17,18,20 or 27:
Wherein said nano wire is the functional part that is selected from following device basically: phonon bandgap devices, quantum dot device, thermoelectric device, photonic device, nano-electromechanical exciter, nano-electromechanical transducer, field-effect transistor, infrared detector, resonant tunneling diode, single-electronic transistor, infrared detector, magnetic sensor, luminescent device, optical adjustment device, fluorescence detector, optical waveguide, optical coupler, optical switch and laser.
56, according to the method for notion 1,8,12,13,17,18,20 or 27, wherein said nano wire is the element of the array of nano wire.
57, a kind of laser comprises: have the nano wire less than the homogeneous diameter basically of about 200nm; With the pumping source.
58, according to the laser of notion 57, wherein said nano wire comprises a plurality of sections of material that composition is different.
59, according to the laser of notion 57, wherein said pumping source constitutes the population inversion (population inversion) that is used for encouraging described nano wire.
60, according to the laser of notion 57, also comprise backing material in addition; Wherein said backing material is selected from solid support material, liquid backing material, polymer support material, glassy backing material and backing material basically.
61, according to the laser of notion 57, also comprise laser cavity.
62, according to the laser of notion 61, wherein said chamber is comprised in the described nano wire.
63, according to the laser of notion 61, wherein said nano wire has the end as the reflector in the described chamber.
64, according to the laser of notion 57, wherein said pumping source is selected from optical source, power supply, thermal source, energy delivery source, plasma source, laser and flashing lamp basically.
65, according to the laser of notion 57: wherein said nano wire comprises the coaxial heterojunction structure nano wire with core and sleeve pipe; With wherein said pumping source be power supply, wherein electric current flows between described core and described sleeve pipe.
66, according to the laser of notion 65, wherein coaxial heterojunction structure nano wire is represented p-n junction.
67, according to the laser of notion 65, one of them electric contact piece is made into described core, and an electric contact piece is made into described sleeve pipe.
68, according to the laser of notion 65: wherein said nano wire comprises vertical heterogeneous structural nano line; With wherein said pumping source be power supply, wherein electric current flows between the section of described vertical heterogeneous structural nano line.
69, according to the laser of notion 68, wherein said vertical heterogeneous structural nano line is represented p-n junction.
70, a kind of laser comprises: a plurality of vertically adjacent sections of the material that the composition of formation nano wire is different; At least one of described section has the uniform basically diameter less than about 200nm; With the pumping source.
71, according to the laser of notion 70, wherein said pumping source constitutes the population inversion that is used for the excited nano line.
72, a kind of laser comprises: have the nano wire of facet end basically, this end has the flat surfaces of the longitudinal growth axle orientation that is substantially perpendicular to described nano wire, and described nano wire has the homogeneous diameter basically less than about 200nm; With the pumping source.
73, a kind of laser comprises: a plurality of vertically adjacent sections of the material that the composition of formation nano wire is different; At least one of described section has the homogeneous diameter basically less than about 200nm; Pumping source with the population inversion that is used for encouraging described nano wire.
74, a kind of laser comprises: have the nano wire less than the homogeneous diameter basically of about 200nm; With the pumping source; Wherein the direction that is parallel to the longitudinal axis of described nano wire from being transmitted in of described laser penetrates away from described nano wire.
75, according to the laser of notion 74, wherein said nano wire is the element in the nano-wire array.
76, according to the laser of notion 74: the described nano wire in the wherein said array is arranged in substantially the same direction; Wherein the direction from the described line of Laser emission in being arranged essentially parallel to described array of described array penetrates.
77, a kind of laser comprises: have the nano wire less than the homogeneous diameter basically of about 200nm; Be arranged on a plurality of quantum dots in the described nano wire; With the pumping source.
78, according to the laser of notion 77, wherein said nano wire comprises a plurality of sections of material that composition is different.
79, according to the laser of notion 77, wherein said pumping source constitutes the population inversion that is used for encouraging described quantum dot.
80, a kind of laser comprises: form vertical adjacent a plurality of sections of the different material of the composition of nano wire; At least one of described section has the uniform basically diameter less than about 200nm; Be arranged on a plurality of quantum dots in the described nano wire; With the pumping source.
81, according to the laser of notion 80, wherein said pumping source constitutes the population inversion that is used for encouraging described quantum dot.
82, a kind of laser comprises: form vertical adjacent a plurality of sections of the different material of the composition of nano wire; At least one of described section has the uniform basically diameter less than about 200nm; Be arranged on a plurality of quantum dots in the described nano wire; Pumping source with the population inversion that is used for encouraging described quantum dot.
83, according to the laser of notion 57,70,72,73,74,77,80 or 82, wherein said nano wire comprises it being the material of crystal basically.
84, according to the laser of notion 57,70,72,73,74,77,80 or 82, wherein said is that the material of crystal is monocrystalline basically basically.
85, according to the laser of notion 57,70,72,73,74,77,80 or 82, wherein said nano wire has the diameter of about 5nm to about 50nm.
86, according to the laser of notion 57,70,72,73,74,77,80 or 82, the diameter of wherein said nano wire can not change about more than 10% on the length of described nano wire.
87, according to the laser of notion 57,70,72,73,74,77,80 or 82, wherein said nano wire comprise be selected from basically II family, III family, IV family, V family and VI family with and ternary material and quaternary material.
88, according to the laser of notion 57,70,72,73,74,77,80 or 82, wherein said nano wire is embedded in the polymeric matrix.
89, according to the laser of notion 57,70,72,73,74,77,80 or 82, wherein said nano wire is the element of nano-wire array.
90, according to the laser of notion 57,70,72,73,74,77,80 or 82, wherein said pumping source comprises optics pumping source.
91, according to the laser of notion 90, wherein said optics pumping source comprises the pumping laser.
92, according to the laser of notion 57,70,72,73,74,77,80 or 82, wherein said pumping source comprises that electric pump send the source.
93, according to the laser of notion 92, wherein said electric pump send the source to comprise anode and negative electrode.
94, according to the laser of notion 93, wherein said anode is electrically connected to described nano wire.
95, according to the laser of notion 94, wherein said electrical connection comprises ohmic contact.
96, according to the laser of notion 94, wherein said electrical connection comprises direct contact.
97, according to the laser of notion 93, wherein said cathodic electricity is connected to described nano wire.
98, according to the laser of notion 97, wherein said electrical connection comprises ohmic contact.
99, according to the laser of notion 97, wherein said electrical connection comprises direct contact.
100, according to the laser of notion 93, wherein said anode and described cathodic electricity are connected to described nano wire.
101, according to the laser of notion 100, wherein said electrical connection comprises ohmic contact.
102, according to the laser of notion 100, wherein said electrical connection comprises direct contact.
103, according to the laser of notion 57,70,72,73,74,77,80 or 82: wherein said nano wire has first and second ends; Has reflecting surface with wherein said first and second ends.
104, according to the laser of notion 103, wherein said nano wire comprises the chamber.
105, a kind of laser comprises: have less than many facets of the homogeneous diameter basically of about 200nm, monocrystalline, ZnO nanostructure; Described nanostructure has first and second ends; Described first end is included in the epitaxial interface between described nanostructure and the Sapphire Substrate, and wherein said nanostructure is extended from described substrate; Described first and second ends have respective reflective surfaces; Wherein said nanostructure is as the resonant cavity between the described end face.
106, according to the laser of notion 105, wherein said nanostructure is embedded in the polymeric matrix.
107, according to the laser of notion 105, wherein said nanostructure is the element of nano-structure array.
108, according to the laser of notion 105, also comprise the pumping source.
109, according to the laser of notion 108, wherein said pumping source comprises optics pumping source.
110, according to the laser of notion 109, wherein said optics pumping source comprises the pumping laser.
111, according to the laser of notion 108, wherein said pumping source comprises that electric pump send the source.
112, according to the laser of notion 111, wherein said electric pump send the source to comprise anode and negative electrode.
113, according to the laser of notion 112, wherein said anode is electrically connected to described nanostructure.
114, according to the laser of notion 112, wherein said cathodic electricity is connected to described nanostructure.
115, according to the laser of notion 112, wherein said anode and described cathodic electricity are connected to described nanostructure.
116, according to the laser of notion 113,114 or 115, wherein said electrical connection comprises ohmic contact.
117, according to the laser of notion 113,114 or 115, wherein said electrical connection comprises direct contact.
118, a kind of laser cavity comprises: the semiconductor structure that can present quantum limitation effect; Wherein said semiconductor structure comprises laser cavity.
119, according to the laser cavity of notion 118, wherein said semiconductor structure comprises nano wire.
Other purpose of the present invention and advantage will be embodied in the following part of specification, and wherein describing in detail is for openly the preferred embodiments of the present invention rather than restriction the present invention all sidedly.
Description of drawings
To more fully understand the present invention by the reference accompanying drawing, accompanying drawing just is used to represent purpose:
Fig. 1 is the schematic diagram of the conversion between the energy various forms of representing to be undertaken by 1-D semiconductive according to the present invention and insulating nano line.
Fig. 2 is the perspective illustration that has the coaxial heterojunction structure nano wire (COHN) of the sleeve pipe on the homostyructure core according to of the present invention.
Fig. 3 is the perspective illustration that has vertical heterogeneous structural nano line (LOHN) of five sections (for example superlattice) according to of the present invention.
Fig. 4 is the perspective illustration that has the coaxial heterojunction structure (COHN) of the segmentation sleeve pipe on the homostyructure core according to of the present invention.
Fig. 5 is the perspective illustration that has the coaxial heterojunction structure (COHN) of segmented core (for example LOHN) according to of the present invention.
Fig. 6 is the perspective illustration that has the coaxial heterojunction structure (COHN) of segmented core (for example LOHN) and segmentation sleeve pipe according to of the present invention.
Fig. 7 is the perspective illustration that has the coaxial heterojunction structure (COHN) of superlattice (for example LOHN) according to of the present invention.
Fig. 8 is the perspective illustration that has the coaxial heterojunction structure (COHN) of the part sleeve pipe on homostyructure core (for example LOHN) according to of the present invention.
Fig. 9 is the perspective illustration that has the coaxial heterojunction structure (COHN) of the part sleeve pipe on segmented core (for example LOHN) according to of the present invention.
Figure 10 is the perspective illustration according to pn heterojunction of the present invention.
Figure 11 is the perspective illustration according to pnp of the present invention, npn, pin, pip heterojunction.
Figure 12 is that expression adopts nano wire bundle as catalyst with use SiH 4Schematic process flow diagram as vapour source according to gas-liquid-solid (VLS) type growth of 1 dimension Si nano wire of the present invention.
Figure 13 is material boron doping Si as p section bar material (p-Si (B)) and the phosphorus doping Si diagrammatic side view according to pn type LOHN of the present invention as n section bar material (n-Si (P)).
Figure 14 is the diagrammatic side view according to Si/Ge LOHN of the present invention.
Figure 15 is the conduction band schematic diagram according to coaxial heterojunction structure nano wire of the present invention (COHN).
Figure 16 is the conduction band schematic diagram according to vertical heterogeneous structural nano line of the present invention (LOHN).
Figure 17 is the schematic diagram according to the band profile of the GaAs of being used for coating of the present invention, GaSb self-assembly quantum dot.
Figure 18 is that expression is used for the curve chart that it is distributed in characteristic Ballistic Electron Emission Microscopy (BEEM) power spectrum that is used for GaSb/GaAs self-assembly quantum dot shown in Figure 17.
Figure 19 is the schematic diagram according to the BEEM structure of the local electronic band structure that is used for determining Si/Ge LOHN of the present invention.
Figure 20 is the curve of expression as the thermal conductivity of the multi-wall carbon nanometer tube bundle of temperature funtion, wherein T 2Be illustrated in the photon restriction among the 2-D, and the dullness increase expression of thermal conductivity has suppressed photon-photon scattering and has had the mean free path of growing very much (approximating 1 μ m) when high temperature.
Figure 21 is the curve that the heat energy of the multi-walled carbon nano-tubes of the miniature manufacturing measurement structure of expression employing is measured, wherein miniature manufacturing measurement structure comprises two suspension heaters, this heater contains with good grounds e bundle photolithographic fabrication line of the present invention, wherein multi-wall carbon nanometer tube bundle passes this two heater block settings, so that these two heater block bridge joints.
Figure 22 is that expression adopts atomic force microscope (AFM) cantilever probe to measure the schematic diagram of measuring the experimental facilities of the electrostatic potential that passes nano wire according to the mechanical movement of piezoelectricity of the present invention or thermoelectric nano-wire simultaneously.
Figure 23 adopts pulse laser to be used for the diagrammatic side view of vapour phase-liquid phase-solid phase (VLS) growth room of a growth of nano wire hetero structure.
Figure 24 is the schematic process flow diagram that expression adopts vapour phase-liquid phase-solid phase (VLS) type according to 1 dimension Si/Ge superlattice structure of the present invention of the growth room shown in Figure 23 to grow.
Figure 25 is according to Si/SiGe superlattice nano line array perspective illustration of the present invention.
Figure 26 is the curve of expression according to X-ray spectral analysis method (EDS) spectrum that can loose in the rich zone of the Ge on the Si/SiGe superlattice nano line of the present invention.
Figure 27 curve that to be the expression growth axis along the Si/SiGe superlattice nano line according to the present invention distribute from the line of the EDS signal of Si and Ge component.
Figure 28 is the curve of expression according to the example that concerns between the growth rate of nano wire of the present invention and the observed diameter.
Figure 29 is the curve of expression ZT to the correlation of the calculating of Bi quantum well (2D) and quantum wire (1D) yardstick.
Figure 30 is based on the diagrammatic side view according to the embodiment of thermoelectric device of the present invention of the n that is embedded in the polymeric matrix or p doping thermoelectric nano-wire array mixture.
Figure 31 is the perspective illustration according to the nano wire polymeric blends array of the present invention that is used for the light radiation formation.
Figure 32 is the schematic diagram according to nano wire base electronics emission light emitting diode/laser diode of the present invention.
Figure 33 is the schematic diagram that has vertical heterogeneous structural nano line (LOHN) of quantum dot according to of the present invention.
Figure 34 is the schematic diagram according to 3 terminal nano-wire devices of the present invention.
Figure 35 is the schematic diagram according to second embodiment of 3 terminal nano-wire devices of the present invention.
Figure 36 is the diagrammatic side view according to the embodiment of the vertical formation dynamo-electric converter based on nano wire of the present invention.
Figure 37 is the profile along the converter shown in Figure 36 of line 37-37 intercepting.
Figure 38 is the diagrammatic side view according to the embodiment of the dynamo-electric converter of the horizontal formation based on nano wire of the present invention.
Figure 39 is the profile along the converter shown in Figure 38 of line 39-39 intercepting.
Figure 40 be expression according to of the present invention on Sapphire Substrate the curve of X-ray diffraction (XRD) figure of growing ZnO nano-wire.
Figure 41 is the curve of the assessment of the emission spectrum that obtains from the pumping power that increases to the ZnO nano wire on the sapphire according to the present invention of expression, wherein curve a represents that excitation density is lower than the spectrum of laser threshold, and curve b and illustration are represented above the spectrum after the laser threshold.
Figure 42 is the curve of the expression integrated emissive porwer from the ZnO nano wire on the sapphire according to the present invention as the function of optics pumping intensity.
Figure 43 be have hex-shaped surfaces that as speculum two have facet naturally according to the schematic diagram as the ZnO nano wire on the sapphire of resonant cavity of the present invention.
Figure 44 is that frequency-tertiary mode locking Ti is adopted in expression: sapphire laser is used for pulse excitation and the curve from the delay of the brightness of the ZnO nano wire on the sapphire according to the present invention of the streak camera with ps resolution that is used to detect.
Embodiment
1, foreword
The present invention includes nanostructure series, we are referred to as " nano wire ".Nano wire according to the present invention generally comprises the heterostructure of at least a crystalline material basically material different with a kind of other composition, wherein forms interface or knot between above-mentioned two kinds of materials.Yet, can also comprise that according to nano wire hetero structure of the present invention wherein material is identical, but have the heterostructure of different crystal orientation.In addition, the surface (homostyructure or heterostructure) according to nano wire of the present invention can functionalised to catch special chemistry or biological species.Crystalline material forms under the situation of heterostructure adopting basically, should be appreciated that the heterostructure that obtains will be a crystal basically.Preferably, at least a material in the heterostructure is monocrystalline basically.To this, if this material presents the regularity of long scope, we are referred to as the material of crystal basically.
Preferably have diameter according to nano wire of the present invention, preferably change less than about 10% presenting on the maximum cross section that changes of diameter along the diameter of the longitudinal axis less than about 200nm at its maximum position.In addition, can have various shape of cross sections, include but not limited to circle, square, rectangle and hexagon according to nano wire of the present invention.For example, the ZnO nano wire has hexagonal cross-section, SnO 2Nano wire has rectangular cross section, and the PbSe nano wire has square cross section, and Si or Ge nano wire have circular cross section.In each case, term " diameter " refers to effective diameter, as what determined by the mean value of the major axis of the cross section of this structure and minor axis.
Should be understood that nano-material of the present invention is to be different from those materials that are commonly referred to semiconductor " whisker that adopt basic VLS growing technology to form basically.Should be understood that the mechanism that is used for these " whiskers " growth is limited to the manufacturing of diameter greater than the semiconductor line of about 1 μ m.
Method of the present invention has been introduced the method for revising the VLS growth, and wherein having suppressed catalyst size serves as the nano wire of about 1nm to about 200nm to form diameter.Because quantum limitation effect, these structures are different from whisker basically, and whisker is bigger than the semi-conductive Bohr exciton of the body radius that forms them, therefore represent unique composition of material.If the characteristic of whisker is promoted to smaller szie simply, then the physics of these materials, optics and electrical property are different from basically and will realize.In the nanowire size scope, these materials are represented a kind of new model of material, and are different from the body material in unique and the unconspicuous mode.The importance of the difference between nano wire and traditional " whisker " should be able to be awared.Whisker provides and the line identical functions that is formed by standard photoetching semiconductor processing techniques thus as little " body (bulk) " semiconductor line work.Yet nano wire described in the present invention shows electronics and the optical property that is different from the body material that forms them substantially, and also is different from " whisker " on characteristic.
Nano wire hetero structure according to the present invention comprises following structure: two or more is that the material of monocrystalline is according to utilizing the ground, mode space of quantum limitation effect to be provided with new with dedicated mode basically.Expect that this scheme not only opens the road that leads to scientific discovery, and the prospect likely that changes energy conversion technique brightly is provided.
In certain embodiments of the present invention, utilize known vapour phase-liquid phase-solid phase (VLS) chemical synthesis process described here to make things convenient for manufacturing.Substantially (not improved) VLS technology also has detailed description in following communique, and it is for reference to quote these documents here as proof: Wagner, R.S., " the VLS mechanism of crystal growth ", whisker technology, 47-119 page or leaf (1970); People's such as Wagner " vapour phase-liquid phase of crystal growth-solid phase mechanism ", Applied Physics collected works, the 4th volume, No. 5,89-99 page or leaf (1964) and Givargize, E., " base case of VLS growth ", Journal ofCrystal Growth, the 31st volume, 20-30 page or leaf (1975).Adopt basic (unmodified) VLS, can grow have greater than the average diameter of about 1 μ m and greater than 50% diameter distribute and up to or surpass the monocrystal nanowire of semi-conducting material (for example Si, Ge, ZnO etc.) of the wide kind of a lot of millimeters.The invention provides the method that forms nano thread structure, this nano wire have less than about 200nm, preferably about 5nm in about 50nm scope diameter and in about 100nm arrives about 100 mu m ranges, the preferred length in about 1 μ m arrives scope between about 20 μ m.
In addition, if the diameter of semiconductor nanowires is reduced to about 5nm to about 50nm, then the quantum limit in electronics and hole allows the manufacturing of the electronics band structure on the one or more farmlands in whole nano wire or the nano wire.This restriction also may influence photon and/or the photon transmission in the nano wire very doughtily, and this is because photon and/or photon spectrum and life-span all may obviously revise.The importance of surface energy and growth anisotropy also provides and will stablize but with body or the metastable synthetic possibility mutually of form of film with the nano wire form in nano wire is synthetic.Therefore, can utilize this mode manufacturing to have the material of special phase and performance.
2, nano wire hetero structure
Referring now to Fig. 2 and 3,, the solution of the present invention comprises as two nano wire hetero structures that are used for the building block of other heterostructure and device: (i) coaxial heterojunction structure nano wire (COHN) 10; (ii) longitudinal axis heterogeneous structural nano line (LOHN) 12.In example shown in Figure 2, COHN 10 comprises that what surrounded by the sleeve pipe 6 of the different material of composition is the core 14 of crystal basically, wherein ties 18 and is formed on therebetween.Sleeve pipe 16 can be crystal or amorphous, polymer, semiconductor, oxide etc. basically.In example shown in Figure 3, LOHN12 comprise other section 22 of the material different with at least one composition adjacent be at least one section 20 of the material of crystal basically, wherein form knot 24 betwixt.
Can be formed with any amount of section according to heterostructure of the present invention, longitudinally with coaxial, and with various versions, introduce some sections wherein below.
For example, Fig. 3 represents the superlattice of additional section 26,28 and 30, shows the situation that heterostructure is not limited to have only two adjacent segment thus.Yet, should be understood that at least two sections can comprise the material that composition is different, so that become heterostructure." composition difference " we refer to (i) this material have different chemical composition (intrinsic or mix) or (ii) this material have different crystal direction (for example identical materials but different crystal orientation).Nano wire hetero structure can comprise that as being the situation of alternation or the constant time range or the multistage nano wire of different materials, wherein at least two sections comprise different materials when the different material of composition when vertically watching.Wherein adjacent segment has the section that the example of the LOHN of heterogeneity is the Si adjacent with SiGe.
Fig. 4-7 expression has the various examples of the COHN of additional section.For example, Fig. 4 represents to have the COHN 32 of core 34 and sleeve pipe, and sleeve pipe comprises first and second section 36,38 respectively.Fig. 5 represent to have surrounded by sleeve pipe 46 and comprise first and second section 42 respectively, the COHN40 of 44 core.Fig. 6 represents to have the COHN 48 of core and sleeve pipe, and core comprises first and second section 50,52 respectively, and sleeve pipe comprises first and second section 54,56 respectively.Fig. 7 represents to have and is surrounded by sleeve pipe 72 and the COHN 58 of the core of the superlattice of the section of comprising 60,62,64,66,68,70.Notice that sleeve pipe can be crystal or amorphous, and can comprise as materials such as polymer, semiconductor, oxides.In addition, COHN can have a plurality of casing layers.
In certain embodiments, can form COHN by partly applying single hop nano wire or LOHN.For example, Fig. 8 represents to have the COHN 74 of single hop core 76, and 76 in this single hop core is partly surrounded by sleeve pipe 78.Fig. 9 represents to have the COHN 80 of LOHN core, this LOHN core section of comprising 82,84, and wherein this core is only partly surrounded by sleeve pipe 86.Perhaps, core can comprise the superlattice with part sleeve pipe.Be also noted that this sleeve portion can be segmentation, in addition, the section of sleeve pipe can be provided with adjacent or at interval.Those skilled in the art can both understand the conventional mask technique of employing can realize these sleeve structures, and these structures are represented several possibility structures based on nano thread structure described here.
Be appreciated that from the explanation of front, the section of heterostructure can comprise various materials, comprise the semi-conducting material of for example doping or non-doping (being pure intrinsic semiconductor), and can be arranged to form the various semiconductor device that have as knots such as pn, pnp, npn, pin, pip.In certain embodiments, can be with usual manner these materials that mix.For example, can use conventional dopant such as B, Ph, As, In and Al.Nano wire and dopant material can be selected from materials such as II, III, IV, V, VI family, and can comprise quaternary and ternary material and oxide.
Although one of invention scheme of the present invention is to believe that usually this nanostructure can not be that " evenly mixing " (promptly mixes, so that dopant molecule disperses in micro-even mode), the just work but as if material of the present invention evenly mix, because if dopant molecule evenly distributes in this material, then they resemble expectation work.This result is unforeseeable, because the small size of high temperature and nano wire will advise that all dopant molecules will be annealed to the surface of line, wherein they will be with the mode work rather than the semi-conductive electrical property of repetition " evenly doping " of catch position (trap sites).
In a large amount of embodiment, desired design of the present invention comprises the nano wire hetero structure of one or more doped semiconductors, and this doped semiconductor is selected from and includes but not limited to Type II-VI semiconductor, type-iii-V semiconductor, Type II-IV semiconductor etc.
Basically can adopt the conduct of a variety of semi-conducting materials and alloy thereof according to the adjacent materials in the nano wire hetero structure of the present invention.For example, Figure 10 schematically shows the nano wire hetero structure 88 as pn junction device 88.Figure 11 schematically shows the nano wire hetero structure as junction devices such as pnp, npn, pin, pip.The general based semiconductor line of a lot of nano wire hetero structures according to the present invention is wherein vertically or radially or at both direction controlled doping and composition, so that make the line that comprises the composition different materials.
As mentioned above, in heterostructure according to the present invention, at least one section comprises it being the material of crystal basically, particularly at its center.Should be understood that the oxide on the nanowire surface can be an amorphous, and what can not destroy nanowire core is the ordering of crystal basically.In addition, nanocrystal may comprise substituent, some dislocation and the combination thereof of defective, atom, and can not destroy the ordering of long in fact scope.Generally speaking, present at this material under the situation of the long scope ordering of essence (for example sorting on the distance at about 100nm), will be considered to be crystal basically and/or be monocrystalline basically.Present at this material under the situation of long scope ordering, then this material be considered to according to of the present invention be crystal basically.Preferably, at least from cross-section center outwards this material 20% with interior be monocrystalline basically.Under the situation of silicon nanowires, preferred epitaxial growth (that is, by be used for the crystal growth of the silicon on silicon wafer by steam precipitation silicon).
According to the diameter of nano wire of the present invention in the maximum gauge position usually less than about 200nm, preferably at about 5nm in about 50nm scope.In addition, the vary in diameter of the integral body of synthetic line is obvious relatively in same process, to such an extent as to the distribution of diameter usually less than about 50%, preferably less than about 20%, is more preferably less than about 10%.Under the cross section of nano wire was not circular situation, term herein " diameter " referred to the mean value of the length of the major axis of nano wire and minor axis, and described plane is perpendicular to the longitudinal axis of nano wire.
In certain embodiments, nano wire according to the present invention passes through on diameter and presents high uniformity usually.Particularly, on the cross section that presents the maximum nano wire that changes of diameter, will preferably be no more than approximately 10%,, be most preferably not exceeding about 5% more preferably no more than about 5%.Can think that diameter variation is by ((d Max-d Min)/d Min) provide.It should be appreciated by those skilled in the art that the end of nano wire will comprise the rapid variation of diameter, may even present infinitely great gradient, wherein above-mentioned measurement considered to be in the position away from the end of nano wire.This measurement preferably is that carry out 5%, more preferably at least 10% position of line length at least in the distance end.In certain embodiments, from the nano wire total length about 1%, preferably up to about 25%, more preferably up to about 75%, most preferably assess vary in diameter up to the length of the nano wire in about 90% the scope.
Definition according to the composition of nano wire hetero structure of the present invention different be that knot between the material of crystal presents high acutance usually basically.For example, according to the present invention, the transition region between these materials can be made to the acutance of total lateral length of nano wire (i.e. the alloy that continuously changes along the length of line) with an about atomic layer.Usually, this transition should be tangible relatively, yet this transition may be across between monoatomic layer and the about 50nm, more preferably between monoatomic layer and about 20nm.
In order under the situation of LOHN, to assess the length of transition (transition region), transition region begins can be defined as the point that moves to second material along the longitudinal axis from first material from first material to second material transition, wherein the deviation of the composition of first material (for example concentration of dopant and/or stock composition) is less than about 20%, be more preferably less than about 10%, be more preferably less than about 5%, most preferably less than about 1%.May be defined as the point that moves to second material along the longitudinal from first material to the end of the transition region of second material transition from first material, wherein when with the material composition (for example concentration of dopant and/or stock concentration) of second material when comparing, the deviation of the material composition of the nano wire of this point is less than about 20%, be more preferably less than about 10%, be more preferably less than about 5%, most preferably less than about 1%.Under the situation of COHN, as the radially beginning and the end of the function measurement transition region of composition from the center of nano wire.In either case, transition region should be represented from the material that is crystal basically, preferably be the variation of the material of monocrystalline to the different material of composition basically.Yet, should be appreciated that owing to can comprise a plurality of sections according to heterostructure of the present invention, can be longitudinally, coaxial or this both direction.Be also to be understood that to form following heterostructure, the some of them knot presents high sharpness, and other knot does not present high sharpness simultaneously, and this depends on special applications and demand.In addition, the material that not only forms adjacent segment can be sharp-pointed or mild, and passes through to control the doping of the material of the section that forms heterostructure, can have sharp-pointed or mild dopant transition between each section.
Referring to Fig. 2, notice that material 14 among the COHN and 16 band structure can so select, so that can realize modulation doping, dopant atom will be arranged in sleeve pipe 16 thus, carrier generally is limited in the core 14.Because the dopant and the observed interface scattering in uncoated nano wire that reduce, this will provide very high electron mobility.This is one dimension (1-D) type by bidimensional (2-D) electronic gas of semiconductor 2-D heterostructure generation.Can for example use this 1-D electronic gas in high-performance thermoelectricity and photonic device then, wherein electron mobility plays an important role.
3, Nano wire is synthetic
Having the nanostructure that reduces yardstick all is interested substantially and technical very important as nano wire.Yet the synthetic huge challenge that has kept for the material supply section scholar of nano wire is because utilize the difficulty of one dimension control.Carbon nano-tube can also be as the template of the nanometer rods for preparing heterogeneity.Also making great efforts to adopt membranaceous template to prepare metal or semiconductor nanorods.Yet these nanometer rods major parts are polycrystal, this part limited their current potential availability.Method for the general and predictability that obtains the trap limiting structure property relationship of these 1D systems, must develop being used for synthetic monocrystal nanowire with uniform-dimension and size ratio.
3.1 VLS mechanism
Nano wire of the present invention and nano wire hetero structure can be synthetic by a variety of methods.Yet, in a preferred embodiment, utilize and revise gas liquid solid (VLS) program synthesis of nano line.Describe in detail in the example that this technology here provides, these be by example provide but do not limit, wherein a large amount of remodeling of signal technology are used in expectation, and fall within the scope of the present invention.
Compare with above-mentioned synthetic schemes, vapour phase-liquid phase-solid phase (VLS) technology is unusual effective method for chemical synthesis monocrystalline 1D nano material.This technology that was used for making the micron-scale whisker in the past and was used to make the nano wire with heterogeneity in recent years is included in nano-scale catalyst liquid dissolved gas reactant, carries out the one-dimensional growth of nanometer monocrystalline whisker then.Selecting catalyst at an easy rate on the basis of analyzing the equilibrium phase bitmap.
Example 1
Referring to the schematic diagram among Figure 12, it shows the example that carries out Si nanowire growth technology on Si (111) substrate 100.In this example, SiH 4Gas 102 is used as catalyst as Si vapour source and Au nano wire bundle 104.Preferably under about 800 ℃ temperature, carry out chemical vapor deposition (CVD) at about 600 ℃.Under this temperature, Au nano wire bundle 104 forms liquid alloy with Si, and spontaneously splits into the nano-scale drop of Au-Si alloy.Then, Si material consecutive deposition is begun the growth of Si nano wire 108 there on the supersaturation gold by silicon in the Au-Si alloy liquid droplet.This technology is proceeded, till nano wire 108 reaches desirable length.Utilize this mechanism in conventional chemical steam conveying/deposit (CVT/CVD) system, successfully to prepare nano wire by Si, Ge and ZnO.Transmission electron microscope (TEM) and X-ray diffraction (XRD) studies show that this inorganic nanowires is the monocrystalline with preferred growth direction (for example Ge is [111]).The diameter of these nano wires can accurately be controlled at the diameter less than about 200nm.Preferably, this diameter be controlled in less than about 100nm, be more preferably less than about 50nm, most preferably less than the diameter of about 25nm, 15nm or 10nm.Have single dispersion diameter distribution and (for example have different size by employing, from about 1nm to about 100nm, more be typically from about 5nm to about 100nm) catalyst nano wire harness (for example Au, Co, Ni, Fe), this nano wire is easy to make (for example, have about 5nm to about 200nm, more be typically about 10nm to the interior diameter of 50nm scope).These catalyst can be dispersed in that Si substrate (for example Si substrate or comprise the substrate that other wishes material) is gone up or the top of mesopore silica film (for example Si film or comprise other film that other wishes material).Also find, adopt different growth times, the size of nano wire than can be from about 1.5 or 2 to 1000000 the order of magnitude, more typically in about 100000 scope, change from about 100.
The position of nano wire on substrate 100 can be controlled by any conventional method of composition catalyst.This method includes but not limited to various sputters and control deposition technology, various mask and/or lithographic technique, incident addition method and combination thereof.In certain embodiments, can be by the film catalyst on the substrate being carried out photoetching composition and heating this film, till it was fused into a plurality of drops, wherein each drop had been made nano-wire array thus as the catalyst of independent nano wire.
In addition, backing material is not limited to Si, and perhaps even homogenous material, for example insulator such as sapphire also can be used as substrate.Generally speaking, when utilizing method of the present invention to form nano wire, can use solvable or any material of suspending in appropriate catalyst.These materials include but not limited to the II of family, III, IV, V and VI, material or its alloy.
Metallic catalyst can be other material except that Au, and is not necessarily limited to homogenous material (for example, various alloy materials are used in expectation).By example, can use Ni catalyst and Ga and NH 3Steam on the C Sapphire Substrate, make the GaN nano wire.Here, optimum growh is in (002) direction.In addition, can adopt MnO 2With the mixture of C Mn doped nanowire.Equally, can adopt Ni catalyst, C Sapphire Substrate and by Co 3O 4The Ga+NH that+C mixture mixes 3→ Co growth Ga (Co) N nano wire.The Ga+NH that can adopt Ni catalyst, C Sapphire Substrate and mix by the ZnO+C mixture 3Growth alloy Ga-N-Zn-O nano wire.
Example 2
Growth in situ with high temperature tem observation Ge nano wire.Here, when specimen heating holder in vacuum chamber, a spot of Ge particle is dispersed on the TEM screen with the Au nano wire bundle, and as the Ge vapour source.Observe that the Au wire harness begins to melt after forming the Ge-Au alloy.Increase at Ge steam solidificating period drop size then.When the Ge composition supersaturation in the drop, the Ge nano wire splits off from alloy liquid droplet (emission) and begins growth.The real time of nanowire growth observes and has directly reflected the mechanism shown in Figure 12.
Based on these observations, several nanowire growth controlling schemes become clearly at once:
(1) can adopt suitable metallic catalyst, gaseous precursors and reaction temperature, synthetic have heterogeneity (for example, Si, Ge, GaAs, CdSe, GaN, AlN, a Bi 2Te 3, ZnO and other composition) inorganic nanowires.Can determine reaction temperature by checking binary or ternary phase diagram.
(2) can use conventional dopant such as B, Ph, As, In and Al.
(3) material can be selected from type-iii-V, II-VI, II-IV etc., and can comprise quaternary composition and three metamembers and oxide.Particularly any semi-conducting material and alloy thereof all can be used as according to the adjacent materials in the nano wire hetero structure of the present invention.
(4), determine nanowire diameter by catalyst size for first approximation.Less nano wire bundle will produce thinner nano wire.This also successfully is confirmed in GaP and Si nanowire system.
Synthetic method of the present invention has been shared more epitaxially grown features in the middle of the surfactant, and wherein the intermediate materials form of deposite metal nano particle or individual layer (respectively with) promotes epitaxial growth by the transformation of forbidding the semiconductor growing surface.Because the instability transformation that must continuously decompose and rebuild, may be optionally and nanowire growth takes place being lower than under the conventional epitaxially grown temperature.Lower temperature provides the chance of the new phase place of visit, so that produce more sharp-pointed interface, and suppresses the form assessment (Rayleigh division) of nano material at growing period.
3.2 The phase equilibrium figure that changes.
Nanowire geometry provides synthesizes in body (bulk) or with the chance of the unsettled phase of form of film.As the result of high surface-volume ratio, surface energy provides the total free energy in the free energy more strongly, particularly for the crystal phase with high anisotropy surface energy.For example, semi-conductive zincblende of III-V and II-VI (cubical) and buergerite (hexagonal crystal system) the equilibrium phase bit boundary between many types of will be with respect to the volumetric balance boundary shifts in pressure and temperature.For example, relatively identical component＜111〉orientation zincblende nano wires and＜0001〉orientation buergerite nano wire, columniform buergerite nano wire is with more close balance (Wulff) shape, the prismatic facet of exposure low-surface-energy.The buergerite phase place is in fact observed as the optimum phase of GaAs in the research before synthetic about the nano wire that utilizes OMCVD.In addition, also utilized the epitaxial relationship between substrate and the nano wire, so that catch the metastable state of nano wire form.This strategy successfully has been used in the film growth.
3.3 Heteroepitaxy in the nano wire
Semiconductor heterostructure will limit electronics and hole, and direct light and selection are mixed, yet if having semiconductor heterostructure in the active area of this device, these interfaces must not have dislocation.Can be subjected to the unmatched restriction of lattice greatly by on given substrate, carrying out the grow scope of material of predetermined thickness of coherence extension.Do not match for given lattice, the balance critical thickness of coherence extension can be assessed with the elastic performance of film and the core energy and the crystallographic knowledge of the dislocation (Burgers vector) that do not match.Though the coherence epitaxial film can be grown to such an extent that surpass the balance critical thickness, film is metastable, so that owing to dislocation mechanism relaxes.Because the change of boundary condition, provide by the nanowire surface structure of method manufacturing of the present invention and to extend balance and dynamics critical thickness (can not matching perhaps equivalently) significantly at the lattice that given thickness holds.
Two main effects are arranged.First elastic boundary condition that is perpendicular to the direction of growth is lax.In desirable film surface structure, the strain energy that is stored in the per unit area coherence film increases along with thickness is linear.In nano wire hetero structure, " film " only laterally is limited at the interface.Along with nano wire " film " thickens, with transverse relaxation, so that the elastic strain energy that stores is saturated.In fact, some strain energy also will be stored in " substrate " side, because the same transverse relaxation of this material.The result will extend with respect to the film value for the unmatched balance critical thickness of given lattice.Not as the film situation, there is the unmatched limited range of lattice, this is relevant with limited critical thickness, and this is because the elastic strain energy that stores is saturated on thickness.What resist mutually with first effect is the strain energy cost relevant with the dislocation strain field that do not match owing to the volume that reduces of nano wire reduces.Yet core energy aspect keeps and expects that therefore first effect preponderates.
3.4 Vertical heterogeneous structural nano line (LOHN)
Mainly determine the success of semiconductive integrated circuit by the ability of defect project by controlled doping.Expectation defect project learning aid has pair nano wire even more deep effect, also produces new device thus because not only will provide to mix, and can also influence electron scattering forcefully.
Adopt method described here, by the continuous input of different dopant gas, along the component distributing (profile) of bobbin generation as shown in Figure 10,11 and 13.For example, in order to realize the LOHN that comprises Si pn knot as shown in figure 13, during nanowire growth, will then use material such as B 2H 6And PH 3CVD technology allows the accurate growth control of component distributing, and can make and have the interfacial knot of sharp-pointed one-tenth.Adopt this scheme shown in Figure 14 also can make the 1-D superlattice 130 of Si/Ge and various III-V, II-VI, II-IV and ternary and quaternary material.Therefore, by continuously changing the gas that in VLS technology, uses, be easy to synthetic LOHN.Generally speaking, this technology will allow the band gap engineering science among the 1-D and also make the sub-point sequence of volume thus.Quantum dot is grown in the solution at present or grows by the island form during film growth.Owing to do not know the position of these quantum dots, therefore be difficult to the independent quantum dot of contact in advance.By accurately integrated quantum dot in single nano wire, contact problems have been eliminated.Therefore obtained the device that we are referred to as " nanometer inline system ".These new 1D nanostructures provide new physics of research low-dimensional system and the chance of phenomenon.They can be used as active nanoelectronics potentially, the nanocomposite optical nanometer thermoelectric is learned or nano-electromechanical is learned device.The nano wire that can also synthesize the different crystal structure is as zincblende and buergerite CdSe and GaN nano wire.By using different substrates and catching some metastable state phase, can realize this point by the relation of the epitaxial growth between substrate and the nano wire.
3.5 Coaxial heterojunction structure nano wire (COHN)
Adopt the nano wire made can also synthesize as shown in Figure 2 co-axial nano structure as physical template.For example, can on the Ge nano wire, obtain carbon coating conformal and uniform by decomposing the lip-deep organic molecule of line.This scheme can be extended the COHN that has the sub-restriction effect of forceful electric power with manufacturing at an easy rate.For example, then can be by adopting cryochemistry vapor deposition process Al 1-XGa XThe thin layer of As applies the GaAs nano wire that adopts VLS to make, and this has been avoided along the crystal growth of bobbin effectively and has promoted Al 1-XGa XThe surperficial outgrowth of As.Yet, notice that sleeve pipe can be crystal or amorphous, and can comprise as materials such as polymer, semiconductor, oxides.For forming COHN, will at first form single hop nano wire or LOHN according to any method described here.The single hop nano wire or the LOHN that will become the core of COHN then are used as the template that forms sleeve pipe.For example, can form sleeve pipe by polymerization single polymerization monomer on the surface of single hop nano wire or COHN.Perhaps, can use any physical vapor deposition (PVD) or chemical vapor deposition (CVD) technology to apply single hop nano wire or LOHN.The example of core/shell material includes but not limited to Si and ZnO, Ge and C, Si and SiO respectively 2, SnO 2And TiO 2, GaN and ZnO, GaAlN and GaN.Attention to the quantity of core/shell material structure basically without limits.Even oxide, also can be used for core material as ZnO.Be the tabulation of core/sleeve structure below, wherein for example core and sleeve pipe all are monocrystalline: TiO 2/ SnO 2M:TiO 2/ SnO 2(M=Mn, Fe, Co, Cr etc.); PbTiO 3/ SnO 2BaTiO 3/ SnO 2LaMnO 3/ SnO 2HTSC/SnO 2(high temperature semiconductors-HTSC); GaAs/GaAlAs.
Be also noted that this scheme can be used for the synthesis of nano pipe.For example, the Ge nanowire core can apply with organic molecule material.Under vacuum, pass through the surface of pyrolysis carbonization organic material then.Evaporate or fusing Ge nano wire under about 1000 ℃ temperature at about 800 ℃ then, form carbon nano-tube thus.In addition, identical technology can be used for forming " nanometer cylinder ", wherein forms the COHN structure, etches away to difference core then, only stays outer tube (or cylinder).This cylinder can be made by any material of making sleeve pipe, includes but not limited to C, Si and SiO 2, SnO 2And TiO 2, GaN and ZnO, GaAlN and GaN.The architectural feature that it is also to be understood that these nano wires will depend on transmission electronic microscope (TEM) and X-ray diffraction (XRD).XRD and TEM will allow to determine the structure/phase place of nano wire.In addition, TEM will provide about the defect sturcture in the independent line, local microstructure, the direction of growth at the interface and the further information of total crystallinity.
4, Nanowire properties
4.1 electronic structure and performance
4.1.1 model manufacturing
Interface roughness and the effect that is localised in the nano wire have been studied in the quantum wire that the static restriction of adopting e-beam lithography or employing to have the separated grid method limits widely.The transition from the trajectory to the diffusion transport, positive and negative magnetic resistance, conductivity quantification and general fluctuation have been observed at low temperature.Adopt the nano wire of technology manufacturing of the present invention that unique chance of studying the electric transmission in the various 1D electronic materials is provided.In addition, identical with CVD deposition film material, the probability of doped nanowire provides the extra degree of freedom to observe the main scattering mechanism in various electron densities.Referring to Fig. 2 and Figure 15, in COHN, mixing than the adjustment of wide bandgap material to allow the apart of ion doping agent 140 and free carrier 142, can realize higher mobility thus.The restraint of liberty charge carrier will reduce the surface scattering effect to the nucleus in the nano wire sleeve pipe.When electronics occupy with the co-axial nano line in the adjacent cylindrical area of heterostructure interface the time, can also form new quantization whisper in sb.'s ear gallery electronic state.Referring to Figure 16, will allow to form quantum dot state 144 along the heterostructure of the direction of LOHN nano wire.These states may influence the Electronic Performance of nano wire greatly.People have observed coulomb a blockade and a 1D resonance tunnel feature.
In certain embodiments, modelling is preferably carried out two stages.At first, adopt sample 1D band structure model and approaching slack time in the electron mobility of higher temperature assessment along nano wire.Utilize more perfect model such as variable range to jump then, so that consider the temperature dependency of surface/interface scattering and calculating electronic conductivity.Other factors can adopt the MonteCarlo simulation of Boltzmann Equation to study as the modification of phonon power spectrum and scattering number of times, electronics-phonon interaction etc.The heterogeneous structural nano line can contain several restrictions and the interface phonon modes that is different from observed such scattered electron in the body semiconductor.
4.1.2 behavioral illustrations
For the Electronic Performance of characterization body and heterogeneous structural nano line, importantly measure doping content distribution along nano wire, electron mobility, in the potential barrier at heterogeneous interface place etc.Conventional body or film characteristics method must be checked before putting on nano-material carefully.Conductivity along nano wire is important parameter, and should characterization on wide temperature range.In addition, the measurement of magnetic resistance will provide surface scattering how to influence the more information of electric transmission.The measurement of thermoelectricity capability (Seebeck coefficient) will provide the more information about the feature of near electron density-state the Fermi surface and scattering mechanism.Adopt the definite heterostructure potential barrier of measurement of heat emission electric current along the nano wire direction.
Ballistic Electron Emission Miroscope (BEEM) is to measure " localization " Electronic Performance of nano thread structure and make one of desirable technique of coaxial heterojunction structure characterization.BEEM is the power low-energy electron microtechnic that is used for horizontal imaging and spectroscopy (having the nm resolution that is used to place under this surface up to the embedding structure at 30nm place).The BEEM technology has been used to study the various self assembly quantum-dot structures of growing on GaAs.
Example 3
The GaSb quantum dot of on GaAS, growing by STM and BEEM image viewing.In the STM image, diameter has been about the high circular structure tag of 50nm and the about 5nm lateral attitude of embedding point.Darker with the zone that point among the STM distributes in the BEEM image of aiming at than the peripheral region, show because electron reflection ends the BEEM electric current that the potential barrier of this point has reduced to pass through this point.The height of this potential barrier (being the partial-band skew) can extract from conducting and the variation by the BEEM power spectrum between the situation.The firing point of several points and cut-off point BEEM power spectrum will cooperate by adopt revising Bell-Kaiser plane tunnel model, the local conduction band offset that provides the GaSb on the GaAs of 0.08 ± 0.02eV to order.Figure 17 shows the conduction band distributing line, and Figure 18 shows the characteristic BEEM power spectrum that is used for GaSb/GaAs self assembly single quantum dot.
Except measuring as the performances such as heterogeneous ligament skew, this technology also is used to study new material such as GaAs 1-XN XOrdering effect on the electronics band structure of alloy, the band structure of GaInP and the resonant tunneling effect that is passed in the InP quantum dot that limits between the AlInP potential barrier.
Know that very BEEM not only can be used for the Electronic Performance of the independent nano wire of characterization, and the remodeling of vertical heterostructure that can characterization type described here, shown in the structure 150 of Figure 19.Restriction effect will cause can be by the structure in the BEEM electric current of secondary derivative (SD) BEEM spectroscopy analysis.
4.2 Optical property
Emission is very challenging from the light of nano wire in observation, because the role of surface state and non-radiative compound at these states.Utilize coaxial heterojunction structure nano wire (COHN) that electronics is limited in the online interior central area.Reduced free surface effect thus.Luminescence generated by light spectroscopy in wide temperature range can be used for studying the light emission from nano wire, and the advantage of having utilized super resolution technology is so that the image that acquisition has wavelet long spacing resolution.In addition, scanning solid impregnating lens can be used for the local light emission of characterization from independent nano wire.The manufacturing of the pn knot in the nano wire and the key that characteristic is photoelectric device are set up one of the condition that stops.DC and pulsation electricity and optical means can be used for measuring photoelectric current, recombination lifetime and the electroluminescence in the nano wire.
4.3 Hot property
Semi-conductive hot property is generally arranged by the transmission of acoustical phonon.The thermal conductivity that produces owing to phonon may be relevant with two fundamental characteristics: (i) phonon dispersion relation; (ii) phonon lifetime.Can adopt following relational expression to calculate thermal conductivity:
k = 1 3 Σ p ∫ v 2 ( p , ∈ ) τ ( r , p , ∈ ) df BE ( ∈ , T ) dT ∈ D ( p , ∈ ) d ∈
Wherein p is the phonon polarization, and (p is that ∈=h ω is a photon energy, f as the group velocity of the function of polarization and energy ∈) to v BE(∈ is a Bose Einstein balanced distribution T), and T is a temperature, and (p ∈) is state density to D, and (r, p ∈) are photon lifetime as the function of position, polarization and energy to τ.(T=0.1 θ at room temperature D, θ D: the Debye temperature), the semi-conductive thermal conductivity of most of bodies is subjected to the restriction of phonon Umklapp scattering.
Phonon transmission in nano wire hetero structure may be different from the phonon transmission in the body semiconductor greatly, and this mainly is because owing to dispersion relation has been revised in the restriction that applies at both direction greatly.The second, the existence of heterostructure interface has been introduced and has been present in this phonon modes at the interface.This cause in the body semiconductor, finding except two laterally and a lot of different phonons the vertical acoustic branch polarize.These modifications of dispersion relation the state density of group velocity and each branch.The phonon variation of temperature derives from two sources.At first, phonon-phonon interaction may change, because depend on dispersion relation based on the selective rule of energy preservation and wavelength-vector correlation.Secondly, boundary scattering may be than stronger in the body semiconductor in nano wire (5-50nm diameter).At last, because the nano wire restriction may allow us to contact new crystal phase, therefore can the degree of depth revise the phonon dispersion relation.
Heat and thermoelectricity capability according to nano wire of the present invention can adopt the miniature manufacturing structure that comprises two suspension heaters to measure, and this heater comprises e-beam lithography and makes line.As test, pass two heater sections multi-wall carbon nanometer tube bundle is set, so that these two heater section bridge joints.By monitoring, extract the nanotube thermal conductivity from the heating input of a heater and the temperature of two heaters.Figure 20 has drawn the curve from the thermal conductivity of 10 ° of K to 350 ° of K as the temperature funtion of multi-walled carbon nano-tubes, shows T 2Hinting the phonon restriction in the 2D material.The dullness of thermal conductivity increases expression and has suppressed phonon and phon scattering and had the mean free path of growing very much (for example approximating 1 μ m).This scheme can also be used to measure the thermal conductivity according to COHN of the present invention and LOHN.In addition, adopt atomic force microscope (AFM) probe of making in batches, wherein temperature sensor is positioned at end, is used for scanning thermal microscope (SThM), so that characterizing Local C OHN and LOHN on the calorifics and on the thermoelectricity.
In certain embodiments, the nano wire characterization is calculated and is concentrated on three aspects: (i) calculate the phonon dispersion relation, (ii) calculate phonon lifetime on sound interaction bases such as dopants scattered, nanowire size and boundary scattering and three phonons, (iii) the phonon transmission is calculated.Owing in dispersion relation, considered wave effect (phonon band gap), therefore can suppose the phase randomization scattering.In these cases, can adopt Monte Carlo simulation to solve Boltzmann transmission equation, illustrate that wherein a state density that different poles in the nano wire is divided and frequency dependence group speed and phonon lifetime are very simple.
4.4 Thermoelectricity
Semi-conductive heat energy depends on three performances basically: (i) near the electronic state density Fermi level, (ii) electron effective mass and (iii) carrier scattering rate.Owing to can change band structure (state density and scattered power) significantly by the quantum of the electronics of restriction in the nano wire, so people can design the band structure and the position of Fermi level, so that formulate heat energy.Above-mentioned suspension heater assembly can be measured the potential difference of temperature and nano wire.For example, Figure 21 shows the heat energy measurement result of the multi-walled carbon nano-tubes in 10 ° K to 350 ° K temperature range.Positive heat energy occurs and represent hole as the domination charge carrier in these carbon nano-tube.Therefore, this device can be used for measuring the heat energy of nano wire hetero structure such as above-mentioned COHN and LOHN.
4.5 Piezoelectric property
Wurtzite structure is supported the bipolar motion of self power generation, and the material that therefore has this structure is thermoelectric and piezoelectricity.Between the mechanical stress and polarization (direct piezoelectricity effect) that these performances allow to apply, between the electric field that applies and the strain (opposite piezoelectric effect) and variations in temperature and polarization change strong linearity coupling between (thermoelectric effect).Therefore buergerite (for example GaAs, InAs, GeN, AlN, ZnO etc.) and nano wire hetero structure can be used as transducer and the exciter of measuring in nanometer potentially.The flow sensor of current potential applies the tuned mass transducer, the heat sensor of nanoscale that comprise integrated atomic force microscope probe, have unimolecule sensitivity, electric field is adjustable GHz filter, big displacement nanometer bundle exciter and nanoscale.
＜0001〉be orientated in the buergerite nano wire, spontaneous polarization is orientated along bobbin.Therefore, electric field and the metal mechanical stress that applies along bobbin will produce maximum piezoelectric response.The simplest electrode structure utilization contacts substrate and top.To read by the direct piezoelectricity effect with the longitudinal stress that top and substrate apply.Because the line cross-sectional area is very little, therefore just can produce big stress with little power.Utilize nano wire as resonant transducer, an end of nano wire must be machinery freely, hithermost conductive surface will be used to detect the electric charge on the nano wire top and remove or add electric charge by tunnel effect.
Figure 22 represents to be used to adopt AFM cantilever probe 164 to measure the piezoelectricity on the conductive substrates 162 or the mechanical movement of thermoelectric nano-wire 160, measures the electrostatic potential of nano wires simultaneously with voltage sensor 166.Metallic catalyst " cap " 168 on the most advanced and sophisticated contact nanometer line of AFM probe is used for electric and mechanical measurement.
5. Growth of single crystalline Si/SiGe
The a lot of potential application that heterostructure and superlattice form for the semiconductor nanowires in the nanoscale photoelectricity is basic.Correspondingly, we have developed and have been used for synthetic mixing pulse laser ablation/chemical vapor deposition (PLA-CVD) technology with semiconductor nanowires of vertical ordering heterostructure.Laser ablation process produces pulsation vapour phase able to programme source, and this impels with one one block mode grow nanowire, and has limited the component distributing along bobbin well.Successfully synthesized monocrystal nanowire with vertical Si/SiGe superlattice structure.The special classification of this of the one-dimensional nano structure of heterostructure has kept the very big potentiality in using as light emitting devices and thermoelectricity etc.
The ability that forms heterostructure by careful controlled doping and interface is depended in the success of semiconductor integrated circuit greatly.In fact, 2 dimension (2D) interfaces are ubiquitous in photoelectric device such as light-emitting diode, laser diode, quantum cascade laser and transistor.Tie up the heterostructure of (1D) nanostructure (nano wire) formation for potential application no less important 1 as effective illuminating source and better thermoelectric device.Although there is the big measured development technology (for example molecular beam epitaxy) that is used to make film heterojunction structure and superlattice, still lack the general synthetic schemes that is used for forming heterojunction and superlattice at present in 1D nanostructure with trap definition coherent boundary.Here, introduced mixing pulse laser ablation/chemical vapor deposition (PLA-CVD) technology that is used for synthesizing semiconductor nanowires with periodic longitudinal heterostructure.Obtain to have the monocrystal nanowire of Si/SiGe superlattice structure and adopted the complete characterization of electron microscope.
Example 4
Referring to Figure 23, wherein show embodiment according to nanowire growth equipment 90 of the present invention.Growth apparatus 170 comprises the stove 172 with crystal reaction tube 174.(111) the Si wafer 176 that applies with the Au thin layer is arranged in the crystal reaction tube 174 as substrate.SiCl 4And H 2Admixture of gas 178 be introduced in continuously in the reaction tube 174 by entering the mouth.Computer programming laser pulse 180 focuses on the pure Ge target 182.Residual gas is extracted out by outlet 184.
Together referring to Figure 23 and Figure 24, adopt Au under aforementioned and as shown in Figure 12 high temperature, to carry out nanowire growth as metal solvent.When this technology begins in the nanoscale drop of metal solvent the dissolved gas reactant, carry out the nucleation and the growth of single crystal wire then.The concept requirement of heterogeneous structural nano line is in the accurate component distributing and the Interface Control of nanometer even atomic level, keeps highly crystalline simultaneously and along the coherent boundary of bobbin.Understand the basic mechanism of VLS nanowire growth based on us, this controlling level can realize by the different vapour sources of continuous feeding.
In one embodiment of the invention, the nanocrystal catalyst of the size Control that can be undertaken by employing of the size of nano wire hetero structure and distribution of sizes is controlled to form nano wire.
Referring to the process chart of Figure 24, in the example shown, the Si/SiGe superlattice nano line be utilize frequency to increase a times Nd-YAG laser (wavelength is 532nm, and 6Hz and power density are 10J/cm 2Each pulse) synthetic by the pulse ablation of pure Ge target 182 with impulse form generation Ge steam.H 2Flow velocity be about 100sccm, SiCl 4And H 2Ratio be about 0.02, this system pressure is an atmospheric pressure.Reaction temperature arrives in about 950 ℃ of scopes at about 850 ℃ usually.Under this temperature, Au film 186 forms liquid alloy with Si, and spontaneously splits into the drop of the Au-Si alloy 188 of nano-scale.Then, Si material consecutive deposition is in the Au-Si alloy liquid droplet, there by the supersaturation Si nano wire 190 that begins to grow.When laser cuts out, have only the Si material to be deposited in the alloy liquid droplet and grown pure Si piece.Yet, if laser is opened in growth course, will produce Ge steam, and Ge and Si material will be deposited in the alloy liquid droplet.When laser is opened, go out SiGe alloy 192 from the solid/liquid interphase precipitate then.By periodic opening and closing laser (this sequence is easy to programming), on each independent nano wire, form Si/SiGe superlattice 194 in one one mode.Whole growth technology is similar to the living polymerization synthetic reaction of block copolymer.
Should be appreciated that and adopt gas with various and target various other nano thread structures of can growing.For example, the PbSe that to grow in the Ar gas that is laser-ablated in by the PbSe/Au target.In addition, the growth according to nano wire superlattice of the present invention is not limited to aforementioned synthesis technique.A kind of alternative can adopt a plurality of target materials and the laser that computerizeds control, and is used to select target material.In addition, in fact can use any physics or the chemical vapor deposition process that adopt steam delivery device, include but not limited to PLD, CVD and MBE.For example, steam delivery device available computers controllable valve constitutes, and wishes the gas flow pulsation so that make.
Example 5
Technology described in the employing example 4 has been synthesized the nano-wire array 200 shown in signal among Figure 25, and obtains scanning electron microscopy (SEM) image of synthesis of nano linear array.In the example shown, the Au film that has 20nm thickness on silicon (111) substrate 202 is become four positions by photoetching composition.Four drops are dissolved in each membranous part position, and these four drops are as the catalyst of relevant nanometer line.In growth course, laser periodically was opened 5 seconds and cut out 25 seconds, and repeated 15 minutes this cycles.As previously shown, preferably along [111] direction growth Si nano wire, this causes the orientation extension nano-wire array growth on Si (111) substrate.Alloy liquid droplet solidifies and is rendered as bright spot at the end 204 of each nano wire 206.The close inspection of nano wire shows the terminal flower shape that forms at the alloy liquid droplet setting up period that has.The diameter of these nano wires is in about 50nm arrives about 300nm scope.The PhilipCM20 transmission electronic microscope (TEM) that employing is worked under 200KeV, scan transfer electron microscope (STEM) image at two nano wires of bright field pattern shows the filaments of sun that periodically occur along bobbin, and this derives from the periodicity deposit of SiGe alloy and Si section.The electron scattering cross section of Ge atom is bigger than Si's.Thereby the SiGe alloy block presents darker than pure Si piece.Adopt the chemical composition of energy dispersive X-ray spectroscopy (EDS) inspection, show that Si peak value and obvious Ge mix (Ge of about 12 weight %), as shown in figure 26 than the dark space.By the focused beam and the variation followed the tracks of from the X ray signal of Si in line and Ge atom of scanning, further determine the periodic adjustment that Ge mixes, as shown in figure 27 along the nanowire growth axle.Si and Ge X ray signal indication are irrelevant periodic adjustment and intensity; In other words, from the X ray signal demonstration maximum of Ge, from the signal demonstration minimum value of Si, this has determined to have formed the Si/SiGe superlattice along bobbin.We notice that the acutance at the Si/SiGe interface in these nano wires of this stage is not desirable.Believe by more accurate and quick steam doping/switch solution of combination such as molecular beam technology and can improve this point.
The elastic boundary condition that it must be emphasized that the heterostructure growth is provided at the possibility that produces the dislocation-free interface in the superlattice nano line, and wherein this superlattice nano line is unsettled in the conventional 2D structure that is realized by the growth of the epitaxial film on the planar substrate.Though the coherence heteroepitaxial film can be grown beyond the balance critical thickness well, this film is metastable, so that relaxed by displacement mechanism.VLS nanowire surface structure provides extends the balance and the dynamic chance of critical thickness significantly, perhaps of equal valuely, because the lattice mismatch that can hold at given thickness that the boundary condition change produces.
The height crystal property of our superlattice nano line is by selecteed regional electronic diffraction (SAED) and high-resolution transmission electronic microscope (HRTEM) and characterization.The SAED figure is registered as perpendicular to the nano wire major axis.This graphical display is for distinguishing the diffraction of axle and advise that nanowire growth takes place along [111] direction along crystal Si [110] then.This further is limited in the HRTEM image, and this image clearly illustrates (111) atomic plane (separately 0.314nm) perpendicular to the nanometer bobbin.When being easy to see the interface contrast in the STEM image, because the low-doped percentage in the SiGe piece, we can not solve the interface in the HRTEM pattern.Yet these HRTEM images clearly illustrate the high crystalline of Si/SiGe superlattice nano line.A large amount of HRTEM images shows that the unijunction crystallinity of Si/SiGe superlattice nano line remains unchanged along the whole line length that is linearity or planar disfigurement hardly.
Structure and chemical composition data show that together the nano wire by PLA-CVD method preparation according to the present invention is the highly crystalline body that has along the Si/SiGe superlattice structure of nanometer bobbin.Be easy to control the diameter of nano wire, concentration and the chemical modulation period of Ge by the conditioned reaction condition.Nanowire diameter is subjected to the influence of the thickness of the Au layer on the substrate.For example, utilize the thick Au film of 20nm, the average diameter of nano wire is about 100nm.If the thickness of Au is reduced to 1nm, then average diameter can be reduced to 20nm.This diameter also is subjected to the influence of reaction temperature, and wherein lower temperature produces thin nano wire.Ge concentration in the superlattice is by being deposited to the Ge atom in the alloy liquid droplet and the proportional control of Si atom.Improve laser intensity or reduce SiCl 4Flow velocity can improve the concentration of Ge.In addition, superlattice period (L) is the speed of growth (V) and laser turn-on and the product of off period (T): L=VxT.Therefore, by reducing the speed of growth or laser turn-on and off period, we can reduce superlattice period.Equally, by changing the ratio of laser turn-on/be easy to regulate the heterogeneity piece by ratio.
Importantly, by these " labels " are placed along the line growth axis, PLA-CVD technology provides a kind of measurement nanowire growth speed (V=L/T) and it quantitative manner with the oversaturated relation of growing.Presetting laser turn-on and off period during T, know superlattice period L, accurately calculated growth speed V.We find that the speed of growth is relevant with diameter under same reaction conditions.Nanowire diameter is more little, and the speed of growth is slow more, as shown in figure 28, wherein shows the relation between the observed speed of growth and diameter in our experiment.This trend is by the quantitative interpretation of Gibbs-Thomson effect, as increasing the Si steam pressure, and diminishes along with nanowire diameter thus and reduces supersaturation.Oversaturated minimizing as the function of nanowire diameter (d) is given as follows:
Δμ kT = Δ μ 0 kT - 4 Ω α vs kT 1 d
Wherein Δ μ has heterodyne, Δ μ in nutrition (vapour phase or liquid phase) mutually and between the chemical potential energy of the Si in the nano wire 0Be the same difference at the interface, α VsBe the specific free energy of nanowire surface, Ω is the atomic volume of Si.Rate of crystalline growth V generally is a non-linear relation for oversaturated correlation, and is the n power under many circumstances:
V = b ( Δμ kT ) n
Wherein b is and the irrelevant coefficient of supersaturation.This causes V naturally 1/nAnd the following linear relationship between the 1/d:
V n = Δ μ 0 kT b n - 4 Ω α vs kT b n 1 d
Wherein Δ μ 0 kT = 4 Ω α vs kT 1 d c
d cIt is cut off diameter.
Our Si/SiGe nanowire growth data can cooperate with n=2 at an easy rate.This observed result meets well about the traditional C VD Study on Crystals Growth by the Si whisker of the nano-scale that Givargizov did.
Use mixing PLA-CVD method described here preparing various other heterostructures on the nano wire separately in " customization " mode, this is can programme because the part vapour source is supplied with (laser ablation).Can on nano wire, prepare various functional devices (for example p-n junction, coupling quantum dot structure and heterojunction bipolar transistor.These nano wires can be used as the important building block that is used to constitute nano-scale electronic circuit and luminescent device.As an example, believe that having the superlattice nano line that reduces phonon transmission and high electron mobility will be thermoelectric device preferably.
6. Nano wire base power conversion device
Those skilled in the art should understand that nano wire described here can be used in the various application widely, includes but not limited to (a) thermoelectric cooling device; (b) light-emitting diode; (c) pickoff.The design of these devices directly background science of the 1D restriction effect on the various physical properties is understood and is carried out.Though this understanding of science may rely on single nano wire research, this device will need a plurality of nano wires to be used to the system of being integrated into obviously.Therefore, adopt the array of nano wire usually.
Example 6
For the purpose of discussing, we will concentrate on above-mentioned three kinds of devices; Yet they can not be unique devices that possible adopt nano wire.
6.1 Thermoelectric cooling device and power produce
Solid-state refrigeration and power produce and can adopt amber and the realization of card (peltier) effect, but flow through the electric current refrigeration (or heating) of thermoelectric knot thus.On the contrary, the temperature difference of passing thermoelectric material produces passes the voltage drop electric current, and produces electrical power thus.Compare with the gas base engine with present vapour compression refrigeration machine, this solid state device is very promising, because: (i) they do not contain any moving-member; (ii) they are wholesome; (iii) allow to minimize.The present reason that they are not widely used is because their performance (efficient and the coefficient of performance (COP) that is used for chiller that are used for engine) is poorer than the gas based system.Yet, make itself and steam based system comparable or better if improve this performance than it, we how to utilize or switching energy on people will be contemplated to an acute variation.This provides the strong and attractive reason of overdevelopment electric installation on the nano wire basis.As described below, this can only adopt nano wire according to the present invention to realize.
The material that is used for solid state heat electric refrigeration device and power generator is a feature with advantage figure, ZT=S 2σ T/K, wherein S is a thermal power, and k is a thermal conductivity, and σ is a conductance, and T is an absolute temperature.Bi 2Te 3Be widely used material at present and have ZT=1 with its alloy.If such shown in ZT=3 in theory, the performance of thermoelectric cooling device and engine and both vapor compression chiller and engine are comparable.In fact, if thermoelectric material is a nanostructure, the quantum limit of electronics and phonon acutely increases their ZT, as shown in figure 29.If between the 10nm, particularly the 1D nano wire can reach ZT and approximates 2 to 5 linear diameter at 5nm.
6.1.1 The nano wire design
Because high electron mobility provides high ZT, then preferably uses COHN, because they will have the dopant and the interface scattering of minimizing.Can adjust the thermal power of COHN by the band gap design.Because the thermal conductivity of material is general and atomic mass (ζ) is inversely proportional to, high ζ material will be selecteed material.So Bi or Bi 2Te 3Nano wire is the good candidate material that is used for thermoelectric applications.Can further reduce thermal conductivity by reducing nanowire diameter, this is to be dominant because wish boundary scattering for the nanowire diameter less than 20nm when the room temperature.Except Bi 2Te 3Outside, also can use other material, as SiGe or InGeAs, wherein alloy scattering can reduce the phonon transmission.
6.1.2 Designs
Because nano wire is crisp, so they should be embedded in the matrix, so that mechanical strength is provided.For example, can be in polymer or dielectric material embedding Bi 2Te 3Or the array of SiGe COHN, as shown in figure 30, so that form thermoelectric device 210.Thermoelectric device 210 shown in Figure 30 comprises at the bottom of the upper and lower electrically insulating substrate 212,214, on the substrate 218 separately the n dopen Nano linear array 216 of growth and on substrate 226 the p dopen Nano linear array 224 of growth separately, wherein nano wire 220 is embedded in the polymeric matrix 222, and nano wire 228 is embedded in the polymeric matrix 230.The wafer set of n and p doping thermoelectric nano-wire array lumps together and is connected so that make electrothermal refrigeration machine or power generator by being electrically connected in series with hot link in parallel.These connections can realize with the Metal Contact pad 232,234,236,238 and 240 that is connected as shown in the figure by forming.By after making nano wire, flowing through polymer solution, adopt heat or UV radiation to make its curing then, can at an easy rate nano-wire array be embedded in the polymeric matrix.In order to make contact 234,240 top of nano wire (promptly), will preferred this polymer of etching downwards, till exposing nano wire, depositing metal contact pad afterwards.
The design parameter of this compound is as follows: (a) superficial density of nano wire; (b) thickness of device.Ideal is the ultralow thermal conductivity (k approximates 0.1W/m-K) of exploitation polymer and the High Power Factor (S of nano wire 2σ), so that realize high ZT.Device performance can pass through to measure the following and characterization: (a) effective conductance of device; (b) effective thermal conductivity of device; (c) effective Seebeck coefficient; (d) temperature difference of the device of response current; (e) electrical power of the response temperature difference or hot-fluid speed.
6.2 Luminescent device
The nano wire composite material has two kinds of visibly different performances that can be used for the luminescent device application.On the one hand, the quantization of restriction of the low dimensional of electronics and energy level can be used for adjusting absorption and emission wavelength.Can allow the more high flexibility of the lattice mismatch between the different materials along the 1D characteristic of the crystal growth of nano wire, and therefore allow to absorb and the wideer variation of emission spectrum.On the other hand, Si and III-V semiconductor have the refractive index of (3-4), this refractive index than air or silica fibre (1-1.5) height.This produces the mode sizes mismatch, and this is one of main difficulty of coupling light between fiber and semiconductor device.Because the photon of emission is absorbed in material once more, so this has also limited the external quantum efficiency of light-emitting diode.
Based on the understanding of science of the electronics band structure of various III-V and II-VI nano wire, can be effectively to absorb and ballistic phonon designs nano wire.For example,,, can make nano wire combination of polymers array 250, make optics active material thus with low availability indexes by a plurality of semiconductor nanowires 252 are integrated in the foregoing polymeric matrix 254 referring to Figure 31.Refractive index polymer is the conventional semi-conductive big or small order of magnitude along with variation of temperature normally is higher than, and this big heat-optical coefficient can make up with the electricity-electrical property of semiconductor nanowires, makes new power conversion device.
Preferably, in order to make and characterize light emitting devices, can be in polymeric matrix integrated nano wire with maximum radiation efficient.In addition, by adopting the mixture of the nano wire of making by different materials, can realize wideer emission spectrum and white light behavior.
Referring to Figure 32, schematically show electronics emission light-emitting diode/laser diode 260, it comprises the nano wire 262 with pn knot 264, wherein this nano wire 262 forms by growing n-type semiconductor 266 and p N-type semiconductor N 268.Positive electrode 270 and negative electrode 272 are attached to respectively on n and the p section bar material.Apply current potential at the electrode two ends by the emission of electronics emission can causing light, shown in figure 32.This structure example forms as adopting ZnO, Si/Ge and GaN with suitable dopants.
Referring to Figure 33, adopt vertical heterogeneous structural nano line (LOHN) 280, can make the influence of single quantum dot LED and research quantum dot size and material to emission spectrum.The special geometry of quantum wire allows directly to point 282 conveying electronics and hole, avoids wherein electronics and the hole will be in compound path, other position thus.Quantum dot for example can adopt Si/Ge, PbSe/PbTe and Bi 2Te 3/ Sb 2Te 3Form.People even synthesis of nano line polymeric media can be put into the vertical cavity insulation speculum inside that distributes are so that provide bulk of optical feedback and research analog transmissions and laser action.
In addition, can make and characterize senior T shape, V flute profile and Ridge quantum wire laser and quantum dot laser.Because the 1D and the 0D performance of electronic state density, these devices have specialized performance.Particularly, the increase of differential gain will improve the High Speed Modulation characteristic.Change in size also is used to change electron energy state and emission spectrum.We wish that the light emission among COHN and the LOHN will produce the power conversion device of new kind, wherein can design photoelectric properties beyond realizing with present method.
6.3 The nano-wire devices flexibility
Therefore, as seen, except above-mentioned device, can be used to make various devices according to nano wire of the present invention and include but not limited to:
(a) high electron mobility nano wire (adopting COHN).
(b) high electron mobility nano-wire field effect transistor (adopt COHN and apply external bias) to exhausting/strengthen raceway groove.
(c) nano wire base infrared detector (adopting LOHN and embedding quantum dot).
(d) nano wire base 1D resonant tunneling diode (adopting LOHN and embedding quantum dot).
(e) nano wire base single-electronic transistor (adopt LOHN and embedding quantum dot and may make up) with COHN.
(f) nano wire base infrared detector (adopting COHN and quantization whisper in sb.'s ear gallery electronic pattern).
(g) nanowire magnetic transducer (the quantization whisper in sb.'s ear gallery electronic pattern that adopts COHN and under magnetic field, be affected).
(h) polymer-nano wire complex light ballistic device (good coupling of high external quantum efficiency, wide spectrum, fiber).
(i) polymer-nano wire complex optics adjuster (can make very high-speed traveling wave adjuster) because electric and speed optical signalling can be mated.
(j) polymer nano rice noodles complex optics detector.
(k) polymer nano rice noodles composite waveguide and coupler (by utilizing the direction raceway groove grow nanowire between the nano wire).
(l) polymer nano rice noodles complex optics switch.
(m) polymer nano rice noodles recombination laser (edge-emission, distributed feed-back or vertical cavity structure).
Be also to be understood that LOHN can be used for making multi-terminal device (being N＞2), as the pnp device.Figure 34 shows the example of the 3 terminal pnp LOHN 290 that make with p section bar material 292, n section bar material 294 and p section bar material 296, and has terminal T 1, T 2And T 3Figure 35 represents another example of 3 terminal LOHN 300.
6.4 The nano-electromechanical device
Thermoelectric and the piezoelectric device of nano wire has the following inherent feature of distinguishing they and film or body device in principle:
(a) High-quality: shortage extension defective should cause the high mechanical quality factor in the nano wire resonator.Fabricating low-defect-density has advised that also low loss tangent and valuable high mechanical-electric coupling quality figure (are proportional to (tan δ) -1).
(b) High S/V: the low quality of per unit length, with the combination at high proportion of absorption site and nano wire volume, detect approaching the resonance that other sensitivity of unimolecule level carries out quality and increase allowing.
(c) Variable-length under the constant situation of quality of materials: the vertical resonator of nano wire can be made from all lengths of sub-micron to tens or hundreds of micron, allows to make the transducer or the exciter of the wide region with fundamental resonance frequency thus.
(d) Nano-sized diameters: minor diameter allows to use the straight probe of piezoelectricity and the power of thermoelectric nano-wire conduct under atom and molecular dimension and the temperature at nano-scale.In addition, " nanometer bundle " unimorph bender of the elastic layer that has longitudinal electrode and made by shadow evaporation will may cause very large skew owing to length: the gauge ratio approached 1000: 1 and had the big transverse electric field (for example for the 100MV/m that applies) of medium voltate between the thick nanometer bundle of 0nm.
Referring to Figure 36 to 39, wherein show the nano-wire devices example of structure that is used for dynamo-electric converter.Figure 36 and Figure 37 show vertical structure, and Figure 38 and Figure 39 show transversary.
Referring to Figure 36 and 37,＜0001〉in the buergerite, spontaneous polarization is longitudinally, promptly is orientated along bobbin.Therefore, electric field and the mechanical stress that applies along bobbin will produce maximum piezoelectric response.In vertical structure 310, the simplest electrode structure has adopted respectively in substrate with at the contact (electrode) 312,314 on top.To read by the vertical compression electrical effect with the longitudinal stress that top and substrate contact apply.Because the cross-sectional area of line is very little, therefore can produce big stress with little power.For example, the single-axle tension of 100nN is (10nm) for cross-sectional area 2The simple stress of the corresponding 100MPa of line.The piezoelectric modulus of 5nC/N will produce 0.5C/m 2Polarization change, this value is detectable.With nano wire as resonant transducer, an end of nano wire must be machinery freely, hithermost conductive surface will be used to detect the electric charge on the nano wire top and remove or add electric charge by tunnel effect.
Referring now to Figure 38 and Figure 39, can be from＜hki0〉the buergerite nano wire expectation of orientation obtains diverse reading and fillip, promptly utilizes the spontaneous polarization perpendicular to the line direction of growth.By selecting the suitable surface orientation of single crystalline substrate, the Sapphire Substrate that for example has (0001) or (hki0) be orientated, this nano wire of can growing.In this transversary 320, electrode can place thread end, therefore activates piezoelectricity shear mode, d 15, or, adopt d along line length 31At the d shown in Figure 38 31In the pattern, wherein electrode 322,324 is along the line length setting, can use the expectation of AlN nano wire big electric breakdown strength (＞300MV/m) and the high fracture strength of zero defect to make high displacement nanometer bundle unimorph bending machine and strength sensor.Suppose that suitable elastic layer crested is deposited on the side opposite with electrode strip of nano wire, the tip displacement δ of nano wire will be at d 31L 2V/t 2The order of magnitude.For the lateral voltage of 1V, the thickness of 10nm, the length of 5 μ m and the d of 3pm/V 31, the tip displacement expectation is about 0.75 μ m.
Transversary shows for the synthetic and processing challenge beyond the desired value of vertical structure.For example, nano wire must be in the horizontal orientation nucleation, and this may form nucleus on crystal buergerite substrate or seed crystal.In case nucleation, the surface energy anisotropy wishes to produce the nano wire of square-section, is desirable for covering deposit.Based on the basic document of testing about the cross growth that utilizes GaN, laterally the speed of growth of nano wire will substantially exceed the speed of growth of vertical buergerite nano wire.In case after synthetic, nanometer bundle unimorph bending machine can be by the following steps manufacturing: metal level cover deposit-a kind of thin flexible metal, so that as electrode (for example Cr/Au), the deposit of covering with second rigid layer (for example Ti/Pt) on opposition side, so that as electrode, and, be used for the position that optimization is used for the central shaft of beam mode excitation as elastic layer.Perhaps, can utilize the different substantially surface property of relative substrate surface, by solution-treated depositing metal selectively.
6.5 Room temperature ultraviolet ray nano wire nano laser
The development of short wavelength semiconductor laser is at present gazed at most.This is realizing with ZnSe and In XGa 1-XN as the room temperature of active layer green-reached the summit on the blue diode laser structure.ZnO is another kind of broad-band gap (3.37eV) compound semiconductor that is suitable for the blue light photovoltaic applications.In fact, the ultraviolet laser effect was reported in unordered ZnO particle and film.For wide bandgap semiconductor materials, for the optical gain of enough height for use in electronics-hole plasma (EHP) technology is provided, laser action needs high carrier concentration usually.This EHP mechanism that is common to the conventional laser diode operation needs high laser threshold usually.As the replacement form of EHP, because its boson performance, the exciton in the semiconductor is compound can be so that low threshold value analog transmissions.In order to realize effective exciton laser effect in room temperature, exciton connects energy (E bEx) must be much larger than heat energy (26meV) in room temperature.About this point, ZnO is good candidate material, because its E bEx is about 60meV, and this is significantly greater than the E of ZnSe (22meV) and GaN (25meV) bEx.
In order further to reduce this threshold value, made low dimensional compound semiconductor nanostructure, wherein quantum size effect be created in band edge state main density with strengthened owing to carrier confinement relative compound.Use semiconductor quantum well structures to represent the obvious progress of semiconductor laser technology as low threshold value optical gain medium.Analog transmissions and optical gain have been proved in they all of Si and CdSe nano wire bundle neutralization in recent years.
According to further scheme of the present invention, we have 40kW/cm under optical excitation 2The ZnO nano wire of threshold value in confirmed the first exciton laser action.Chemistry flexibility and one-dimensional nano line make them be made for the desirable laser light source that minimizes.These short wavelength's nano lasers can have a lot of application, comprise optical computing, information storage and nanometer analysis.
Example 7
Adopt vapor transport technology through the synthetic ZnO nano wire of the growth of the catalysis epitaxial crystal on sapphire (110) substrate.Patterned Au film is as the catalyst of nanowire growth.For nanowire growth, under the situation of using or do not use the TEM screen as shadow mask (the micron contact print of the mercaptan on Au, selective etching also can be used for making the Au figure then), the gold thick with the 10-35 dust applies clean (110) Sapphire Substrate.The ZnO powder and the powdered graphite of grinding equivalent also is transported in the aluminum ship shape vessel.It is the position of 0.5-2.5cm that common Sapphire Substrate with coated aluminium places the center apart from the ship shape vessel.In argon stream, original material and substrate are heated to 880 ℃ to 905 ℃ then.Carbon thermal reduction by ZnO produces Zn steam, and sends Zn steam to substrate, at the substrate growing ZnO nano-wire.Growth generally took place in 2-10 minute.
The nano wire epitaxial growth is on substrate and form height-oriented array.When using patterned Au film, be easy to realize the nanowire growth selected.The ZnO nano wire only is grown in the Au coating zone with excellent selection rate, and this is because the catalytic performance of Au thin layer.The zone of these nano-wire arrays is easy to extend to cm 2Usually, the diameter of these lines is in 20nm arrives the 150nm scope, and great majority have the diameter of 70nm to 100nm in the middle of their.Diameter disperse to be because the inhomogeneous size of Au nano wire bundle catalyst causes when during growth technique substrate being annealed.By adjusting growth time, the length of these nano wires can change between 2 μ m and 10 μ m.This ability of patterning nano line growth allows us to make the optical transmitting set of nano-scale with controlled manner on substrate.
We find that nearly all nano wire is all from the substrate vertical-growth.This is because good epitaxial interface is present between (110) face of (0001) face of ZnO nano wire and substrate.Sapphire desirable α face (110) is two folding symmetries, and ZnO c-face is six folding symmetries.They are inappropriate basically, except there are almost accurately 4 times of relations in the c axle of the α axle of ZnO and Sapphire Substrate (mismatch is less than 0.08% under the room temperature).This coupling that meets along sapphire [0001] direction, the strong trend that is accompanied by ZnO causes special vertical epitaxial growth structure with the interface incoherence on c orientation and sapphire [0001] direction in addition.The anisotropy of sapphire α face is crucial for growing high-quality c oriented ZnO nano linear array.
Obtained the SEM image of nano-wire array.Can clearly distinguish the hexagon end face of nano wire.This is that these nano wires are along＜0001〉direction growth and the strong evidence that in fact good facet is arranged on end face and side surface.When these nano wires are used as effective laser medium, the good facet performance of these nano wires will have important implication.
The additional structural features employing transmission electronic microscope (TEM) of ZnO nano wire carries out.Obtain the high-resolution TEM image of single crystal ZnO nano wire.Distance between corresponding two (0002) crystal faces in the interval of 2.56 ± 0.05 dusts between the adjacent cells face, and further expression＜0001〉be the preferred growth direction of ZNO nano wire.Importantly, on the Sapphire Substrate this＜0001〉optimized nanowire growth also be reflected in the X-ray diffraction figure shown in Figure 40 in the SiemensZ5000 photographs.Only observe (0001) peak value, this overall c axle that shows the excellence of these nano-wire arrays on big Substrate Area is aimed at.
Adopt He-Cd laser (325nm) to measure the photoluminescence spectra of nano wire as driving source.Observe strong near band gap edge-emission at～377nm.In order to explore the possible analog transmissions from these directional nano lines, detection power associated transmissions.Four-time harmonic by Nd:YAG laser (266nm, 3ns pulse duration) is pumping sample optically at room temperature.The pumping light beam becomes the incidence angle of 10 degree to focus on the nano wire with the symmetry axis with respect to nano wire.Collecting the light emission perpendicular to the direction on the end face plane (along symmetry axis) of nano wire.Adopt monochromator (ISA) and in conjunction with Peltier-cooled CCD (EG﹠amp; G) collect from the analog transmissions of nano wire along the direction of the normal line of butt end of nano wire.All experiments are all at room temperature carried out.Importantly, under without any the situation of making speculum, we observe the laser action in these ZnO nano wires.
Figure 41 shows the assessment of the emission spectrum that increases along with pumping power.In low excitation intensity (below laser threshold), (curve a) constitutes spectrum by having the wide spontaneous emission peak of list in the overall with of half maximum (FWHM) of about 17nm.This spontaneous emission is at the following 140meV of band gap (3.37eV), and general compound owing to the exciton that causes by exciton and exciton collision process, the compound generation photon in one of exciton radiation ground in this process.When pumping power increases, emission peak is narrowed down owing to amplifying near near the best of the frequency the maximum that obtains spectrum.When excitation intensity surpasses laser threshold (～40kW/cm 2) time, sharp peak value appears in emission spectrum (curve b and insert).The pumping power of these spectrum is respectively 20,100 and 150kW/cm 2The live width of these peak values is less than 0.3nm, and this is littler more than 50 times than the live width at the spontaneous emission peak below the threshold value.More than above-mentioned threshold value, the integration emissive porwer is along with the pumping rule increases fast, as shown in figure 42.The narrow linewidth of emissive porwer and quick increase are illustrated in these nano wires analog transmissions have taken place.Observed single or a plurality of sharp peak value (Figure 41) curve b and insert) be presented at 370 and 400nm between the different zlasing modes of wavelength.Observe, with the Random Laser (～300kW/cm that is used at unordered particle or film 2) the value of previous report to compare laser threshold very low.Importantly, these short wavelength's nano wire nano lasers are at room temperature worked, and the surface strength of these nano lasers is easy to reach 1.1 * 10 10Cm -2
We need not observe laser action under the situation of any manufacturing speculum in these nano-wire arrays, impel us to consider that the nano wire of these monocrystalline, good facet is used as the natural resonance chamber to amplify analog transmissions.Figure 43 schematically shows the nano laser 330 that many facets that employing grows (being hexagon in this example) ZnO nano wire 332 is made on Sapphire Substrate 334.Notice that in this is used nano wire 332 is not heterostructure but homostyructure, yet, should be appreciated that the present invention can be heterostructure laser and homostyructure laser.This nano wire is as the resonant cavity with two natural facet hexagon end faces 336,338, and end face 336,338 is as speculum.Large-scale resonator volume effects may cause in these nano-wire arrays producing the analog transmissions of exciton, wherein this large-scale resonator volume effects may have bigger but take place in the little high-quality nano wire crystal than exciton Bohr radius than optical wavelength.For the II-VI semiconductor, the edge that splits of sample is usually as speculum.For our nano wire, an end is the epitaxial interface 336 between Sapphire Substrate 334 and ZnO, and the other end is sharp-pointed (0001) plane 338 of ZnO nanocrystal.The refractive index of considering sapphire, ZnO and air is respectively 1.8,2.45 and 1.0, and they can both be used as good laser cavity speculum.Notice that this is the key property of this nano wire, promptly can be at an easy rate in abutting connection with waveguide.Form in nano wire that this natural cavity waveguide is advised simple chemical scheme need not split and etching so that form the nano wire laser cavity.In fact, when these nano wires are observed a plurality of zlasing mode (Figure 41 insertion), for the long line of～5 μ m, observed mode spacing is about 5nm, and this meets the adjacent resonance frequency V of calculating well quantitatively FInterval between the=c/2nl, wherein V FBe the emission mode interval, c is the light velocity, and n is a refractive index, and l is a cavity length.Be also noted that the substitute mode that can form waveguide can be with polymeric layer coated with nano line.
According to laser of the present invention can have solid polymer or glassy matrix upper support, in solution or extend to nano wire beyond the substrate surface.For the line that is fixed on the substrate, line can be unordered or arrange, so that they are all located at equidirectional.This direction can be perpendicular to substrate surface, and perhaps can select is to become any other angle with substrate.In addition, in addition the nano wire in the basis material can arrange so that they form orderly structure.Notice the present invention includes have above-mentioned set of nanowires conjunction to laser and the non-laser heterostructure of identical formation.
Employing is used for the frequency tertiary mode locking Ti of pulse excitation (200fs pulse length): sapphire laser and the streak camera with ps resolution that is used to detect are studied the luminance delay from the ZnO nano wire.Referring to Figure 44, suppose fast and slow procedure has the time steady state value of about 70ps and 350ps respectively, utilize the second order delayed mode to obtain for well suitable (straight line) of the experimental data (dotted line) of record at room temperature.Exciting power resolved spectroscopy writing time at 6.39mW.Therefore, these lifetime measurements show that the radiation recombination of exciton is the overlapping of quick and slow procedure.The brightness life-span, mainly by the defect density decision, they caught electronics and/or hole, and make their nm radiation compound at last.Though still do not know the accurate reason of luminance delay in this stage, the very long life-span that measures for these lines shows utilizes this nanowire growth technology to realize high-crystal quality.Simultaneously, also consider low laser threshold described here.
In a word, we are verified has 40kW/cm 2The good orientation vertical Z nO nano-wire array of laser threshold in the room temperature Ultra-Violet Laser.The area density of these nano lasers on the substrate can reach 1.1 * 10 at an easy rate 10Cm -2We can expect optical maser wavelength can be adjusted to blue region by the alloy nano-wire of making ZnO/CdO, and people should test the coupling electronics emission blue laser from independent nano wire.This nano wire nano laser that minimizes will be found application in nanophotonics and miniature analytics.
Be understood that from the explanation of front nano wire according to the present invention can be used as optics cavity.Make the another way of optics cavity insulating material is made in online end.In addition, some part of nano wire can have an energy transport process (event) and other parts have different energy transport process, as in distributed feedback laser.Also understand by covering the end of (capping off) optics cavity, can realize laser or image intensifer.In addition, the chamber can be the part of aforementioned nano wire itself, and this chamber can be positioned at the outside of nano wire.In fact, laser or image intensifer can be formed by nano wire, pumping source and chamber, and wherein this chamber is the part of nano wire or separates with nano wire.In addition, adopt the conventional simulation lift-off technology, do not need the chamber.
Also understanding can be as the functional part of quantum dot laser according to nano wire of the present invention, as described in the U.S. Pat 5260957, here it is for reference to quote the document as proof, wherein quantum dot will be integrated in the nano wire described here, and the pumping source can constitute the overall inversion that is used for excitation quantum point.Yet, notice that nano wire itself can be pumped and be used for Laser emission, wherein pumping promotes the overall inversion in the nano wire.This nano wire can be embedded in the polymeric matrix, as previously mentioned, and can be as the element in the matrix of this Laser Devices.The pumping source can be optics pumping source, and as the pumping laser, or the electric pump with anode and negative electrode send the source, and anode directly or by ohmic contact contacts with nano wire with negative electrode.If adopt the pumping laser, then more than the about 10meV of height of the preferred ratio nano line of the wavelength in this pumping source, more than the more preferably high 100meV.This nano wire can be placed in the chamber or end can be formed with reflecting surface, so that this nano wire is as the chamber.
6.6 Other device
Be appreciated that from the explanation of front, adopt aforementioned nano wire and synthetic method can make a large amount of devices.Other particular device includes but not limited to following each device.
6.6.1 Field ballistic transistor (FET)
This is the three terminal device that available COHN realizes.Can control the electric current that flows to " drain electrode " from " source electrode " by voltage at " grid ".Source electrode and drain electrode can be on along the nano wire of contact nanometer core any 2.Grid contact certain point between source electrode and drain electrode puts on the nano wire sleeve pipe.The conductivity of the raceway groove between grid voltage control source electrode and the drain electrode.Utilize this mode can make at least two kinds of FET.At first, knot FET is formed with the knot at the reverse bias pn of grid.In this case, n N-type semiconductor N and sleeve pipe are p type (or vice versa) on the nanowire core.Tie to apply the depletion region that reverse bias will increase in-core portion at this, therefore stoped electric current to flow to drain electrode from source electrode.Second kind of FET is based on the metal-oxide (MOSFET) or metal-insulator (MISFET) contact of grid.In this case, the nano wire sleeve pipe is made of two sub-sleeve pipes.Nanowire core is at first covered by one deck oxide or insulator, covers with conductive layer then.Can remove raceway groove between source electrode and the drain electrode (depletion-mode MOSFET or MISFET) applying voltage between conductive casings and the nanowire core, if perhaps nanowire core does not have conducting channel between source electrode and drain electrode when zero grid voltage, then produce this raceway groove (enhancement mode MOSFET or MISFET).In addition, three terminal device, as but be not limited to can so use as shown in Figure 34 and 35, wherein two ends are as source electrode and drain electrode, the 3rd end is as grid.Particularly, can make the three terminal device of MOSFET structure, wherein Jue Yuan heterojunction places between source-drain path and the grid.
6.6.2 Infrared detector
The nano wire that employing is made by semiconductive material can be made into infrared (IR) detector, and wherein said semiconductive material has the band gap in infrared wavelength (1-20 micron).This detector is two terminal device preferably, has two contacts at the two ends of this nano wire.The existence of light has changed the conductivity of nano wire, and this is to adopt the biasing that applies between two ends (photoconductor) to measure; Perhaps under the situation that does not have external bias circuit (photo work), light passes nano wire and produces voltage.Photo work need be in nano wire internal electric field.This can adopt along the p-n junction of nano wire or tying to the metal/semiconductor of the contact position at nano wire two ends and realize.When nanowire diameter during less than the electronics deBroglie wavelength of electronics, quantum limitation effect will change effective band gap of material and to the zone of the sensitivity of IR radiation.Can make second kind of IR detector with LOHN.The same with photoelectric detector between the infrared sub-band of quantum well, along a series of heterostructures of nano wire direction conduction band or inner quantization electronic state that produces of valence band at material.Optical absorption between these electronic states can be adjusted to any IP wavelength (1-20 micron), is not subjected to the restriction of the band gap of material.Contact at the nano wire two ends will allow to realize photoconduction or photoelectricity IR detector.
6.6.3 The single electron infrared detector
This device is similar to the LOHN base infrared detector of front.Unique difference is to select heterostructure layer parameter (length, nanowire diameter, composition), so that the free electron in the certain layer changes electrostatic energy, makes other electronics can pass this layer transmission, till free electron leaves (coulomb sealing).This just can detect single electron (so single photon) incident.
6.6.4 Resonant tunneling diode
This is the two terminal device that is made of LOHN.Basic thought is that LOHN is divided into five sections (emitter, barrier layer 1, trap, barrier layer 2, collector electrode).The trap layer is enough short, so that electron energy state quantization.To such an extent as to it is unsettled that the band structure on barrier layer is so selected the electron waves function, but the electric transmission probability that passes this layer is not zero.Under biasing, contact to collector electrode from emitter contact emitting electrons.Under special biasing, so that come the quantized level in the corresponding trap of energy of incident electron of self-electrode, the transmission of passing total has strengthened (resonant tunneling effect), this causes existing negative differential resistance in device current-voltage characteristic, and can be by the example utilization, so that make high-speed oscillator or logical circuit.
6.6.5 Light-emitting diode
-single nano-wire LED can be made along nano wire by the pn knot.Near the depletion region heterostructure (electronics and hole are compound therein) can be used to make more effective LED by limiting carrier.In order to make LED, importantly in conjunction with suitable filler (polymer etc.) with low absorption and scattering loss with nano-wire array.Last device will be made of two electrodes, and have the set of nanowires compound therebetween.
6.6.6 Electronics pumping laser
This adds that by the nano wire composite LED optics cavity constitutes.Optics cavity can be made of the dielectric mirror of vertical stratification (being accompanied by the contact of the both sides of nano wire composite material) or horizontal structure (being similar to distribution Bragg reflection laser).
6.6.7 Optical waveguide/interconnection
In this structure, nano wire is directed in nano wire itself as a part of composite material (nano wire adds packing material) or light.Under the kind situation of back, the major parameter in the design is the quantity along the optical loss and the transverse mode of line.Typically design, wherein select the index of core and sleeve pipe so that realize the bootmode or the group dispersion value (this is similar to the design of silica-based optical fiber) of particular number based on COHN.For preceding kind of situation (nano wire composite material), can be used as new designing material and handle, and can adopt conventional method to make waveguide (ridge type, flaggy etc.).
6.6.8 Optical coupler/modulator/switch
Under the situation of nano wire composite material, basically, we will have packing material (for example polymer), and its electron optics, hot optics or magnetooptics performance are adjusted by the combination of nano-wire array.Can select different materials and various linear diameter, so that adjust required performance (increase the electro-optical coefficient, have the combination optical gain of nano wire pn knot etc.).In case made the nano wire composite material, can be used as new thin-film material and handle, can use routine techniques to realize waveguide switch, modulator, coupler etc.Major advantage is that the rich performance of passive and active heterogeneous structural nano line combines with the simple process of polymer-based films device.
6.6.9 Electromechanics/hot machine spare
The nano wire that is made of piezoelectricity or pressure drag material can be used as pickoff.Under the situation of uniaxial strain, in the direction (vertically) along line, piezoelectricity (for example AlN, ZnO) nano wire can produce voltage signal, the variation and pressure drag nano wire (for example Si) will have a resistance, and this can measure by flowing through electric current.When these form the polymer nature combination, can obtain to can be used for detecting the flexibility/compliant material of uniaxial strain basically.Piezoelectric device can be used for producing the single shaft motion.If utilize following mode to form nano wire hetero structure: apply a side of monocrystal nanowire with other material (portion C OHN for example described here), it can be used as twin crystal and is used to produce bending motion then.For example, if two kinds of materials have different heat expansion coefficient, then they can be used for any process (radiation absorption, electric consumption etc.) of detected temperatures and change temperature.In addition, by changing temperature, this device can be used for thermal excitation.Nano wire base twin crystal also can be used for detection of vertical in the axial any strain of nano wire.
6.6.10 The chemical sensitisation device
When nano wire can be used as chemical sensor, they also can be used for chemical logic.For example, consider LOHN, it has the section of materials A, B, C.Suggestion materials A when materials A absorption chemical composition A ' conduction that becomes, the B conduction that becomes when B absorbing material B ' equally.Only under the situation that has chemical composition A ', B ' and C ', will in nano wire, there be high conductivity now.This is a kind of chemical logic, i.e. A ', B ' and C '=1 is to such an extent as to A ' and B ' rather than C ' equal 0.If you place series connection/parallel network with these structures, will produce AND and OR logic.Certainly this is extended to Biological Detection.In fact, be easily for Biological Detection, because biological recipient is highly special.
7. Conclusion
From aforementioned discussion, find out, when semiconductor is restricted to 2,1 or 0 dimension during structure in the size range less than about 200nm, and preferably at about 5nm in the 50nm scope, can use their performance with new method.Method described here is accompanied by other chemical synthesising technology can be used for grow nanowire and relevant heterostructure.These structures comprise coaxial heterojunction structure nano wire (COHN) and vertically heterogeneous structural nano line (LOHN) and combination thereof.COHN allows to adjust and mixes, so that can obtain to have the nano wire of high charge carrier mobility, LOHN allows the band gap in the 1D design simultaneously, and this can cause integrated many quantum dots or pn knot in single nano wire.Near the design Fermi level band structure also will allow to adjust their thermoelectricity capability.The 1D restriction has a significant impact phonon spectrum and life-span, and this can change their hot property greatly.In addition, nano wire hetero structure provides the prospect likely of integrated piezoelectric heterostructure and semiconductive nano wire, produces the nano-electromechanical converter.And the elastic boundary condition among COHN and the LOHN is created in unsettled dislocation-free interface in 2D (quantum well and heterostructure) or the form of film, and providing approaching simultaneously is metastable new stable phase in body or form of film.
COHN and LOHN also make them oneself develop into the power conversion device, comprise thermoelectric cooling device or power generator, luminescent device and nano-electromechanical converter.Active material in these devices comprises the composition that is made of the nano-wire array that preferably is embedded in the polymeric matrix, so that they can be patterned and be integrated into microsystem.Diameter provides to the semiconductive nano wire in the 10nm scope at 5nm to have with comparable based on those devices of gas or steam or than the special chance of its good thermoelectric cooling device and power generator.It is this so the attitude device may have tremendous influence to energy use technology and environment.The nano wire that use contains integrated quantum dot can realize all effectively with the opto-electronic conversion of adjusted size.
In addition, embedding these nano wires will produce luminous flexible media in polymeric matrix, and it has and is lower than semi-conductive availability indexes, and this will cause the effective coupling with optical fiber, and improve external quantum efficiency thus greatly.When learning the device combination with single electron, this quantum dot nano line will provide the possibility of the single photon device of energy appreciable impact information stores and processing.Nano wire base piezoelectric sender will cause high-quality and high resonance frequency device, the application in can be used for from Molecular Detection and nanometer exciter to the high-frequency signal processor scope.At last, the monocrystal nanowire of portraying end face naturally that has as speculum can be used for the nanometer laser device.
The LOHN that contains heterostructure along nanowire length also can be designed to have very properties of interest, include but not limited to: (a) pn or pnp or can be used for various other knots of photonic device, (b) have the optical absorption/emission of size adjustable and a plurality of quantum dots of single electron tunnel performance, produce the single photon device thus, (c) have the nano wire superlattice of the phonon transmission of high electron mobility and minimizing, can be used for thermoelectric device thus; (d) be used for piezoelectricity and the heterogeneous device of electronics that nano-electromechanical is changed.The elastic boundary condition that is also noted that the nano wire heteroepitaxial growth is provided at the possibility that produces the dislocation-free interface in the superlattice nano line, and wherein this interface is unsettled in the conventional 2D structure that realizes by the growth of the epitaxial film on planar substrate.On the other hand, the situation that exists hope to have dislocation, and the present invention allows to be used for to detect control.
Though a large amount of effort of past all concentrates on compound and research zero dimension (0-D) (quantum dot) and 2-D (quantum well and heterostructure) nanostructure, seldom notices carbon nano-tube semiconductive nano wire in addition.Yet, notice, compare with quantum dot, the special chance that about 1 μ m provides the structure with nanostructure and the miniature manufacturing of photoetching to integrate to the long nano wire of about 10 μ m, the structure of described miniature manufacturing generally approximates 1 μ m.In addition, nano wire also allows the structural further restriction at 2-D, and the past is broad research and used this 2-D structure.Because these organic features can design and make the device based on various other types of nano wire hetero structure, include but not limited to: (i) high efficiency thermoelectric chiller or power generator; (ii) adjustable light-emitting diode; (iii) piezoelectric nano mechanical pick-up device and exciter.It is crucial using nano wire hetero structure in these devices, because they have improved conversion efficiency greatly or have opened the new route of conversion, describes in detail as the back.These simple Devices also are formed for the more basis of complex devices.
Should be appreciated that and adopt aforementioned structure of the present invention can realize various structures, wherein the front by the agency of a part.By further example, but do not limit the present invention, these structures can comprise single and many knot LOHN, lists and tie the combinations of combination, two-end structure, N＞2 end structures, heterostructure and the homostyructure of COHN, LOHN and COHN more, have one or more electrodes (can also be whole heterostructures) homostyructure, have one or more electrodes heterostructure, have insulator homostyructure, have the heterostructure of insulator etc.Should also be appreciated that the interface between nano wire and the terminal constitutes heterojunction.Adopt these structures and constitute and to make various devices, include but not limited to the photon band gap device, electronics is limited in quantum dot, thermoelectric device (for example solid-state chiller and engine), photonic device (for example nano laser), nano-electromechanical (MEM) device (dynamo-electric exciter and transducer), various forms of power conversion device in the special area, for example comprise light to mechanical energy or heat energy device to transform light energy, and other device.
Though this specification front has comprised a lot of details, these details should not constitute the restriction to scope of the present invention, and only provide the explanation of the preferred embodiment of the present invention.Therefore, should be appreciated that scope of the present invention comprises for those skilled in the art other embodiment clearly fully, scope of the present invention is correspondingly limited by appended claims, wherein the odd number element is not tending towards expression " and have only ", unless otherwise indicated, be meant " one or more ".To those skilled in the art all be known above preferred embodiment element all structures, chemistry and function equivalent here by with reference to form in conjunction with expression, and be tending towards comprising by appended claims.And, for the device of each problem that solves by the present invention from thing or method not necessarily, but by appended claims comprised.In addition, the element in the disclosure, parts or method step are not tending towards the present invention is contributed, and this is with whether clearly to put down in writing element, parts or method step in claims irrelevant.Here the element that does not require protection will explain under the regulation of 35U.S.C.112, chapter 6, unless use phrase " be used for ... device " conclusively show this element.

Claims (17)

1. laser comprises:
Has nano wire less than the homogeneous diameter basically of 200nm;
The pumping source;
Wherein said nano wire comprises the coaxial heterojunction structure nano wire with core and sleeve pipe; With
Wherein said pumping source is a power supply, and wherein electric current flows between described core and described sleeve pipe.
2. according to the laser of claim 1, wherein said nano wire comprises a plurality of sections of material that composition is different.
3. according to the laser of claim 1, wherein said pumping source constitutes the population inversion that is used for encouraging described nano wire.
4. according to the laser of claim 1, also comprise backing material in addition; Wherein said backing material is selected from solid support material and liquid backing material.
5. according to the laser of claim 1, also comprise backing material in addition; Wherein said backing material is the polymer support material.
6. according to the laser of claim 1, also comprise backing material in addition; Wherein said backing material is glassy backing material.
7. according to the laser of claim 1, also comprise backing material in addition; Wherein said backing material is a backing material.
8. according to the laser of claim 1, also comprise laser cavity.
9. laser according to Claim 8, wherein said chamber is comprised in the described nano wire.
10. laser according to Claim 8, wherein said nano wire have the end as the reflector in the described chamber.
11. according to the laser of claim 1, wherein said pumping source is the energy delivery source.
12. according to the laser of claim 1, wherein said pumping source is selected from optical source, power supply, thermal source and plasma source.
13. according to the laser of claim 1, wherein said pumping source is selected from laser and flashing lamp.
14. according to the laser of claim 1, wherein coaxial heterojunction structure nano wire is represented p-n junction.
15. according to the laser of claim 1, one of them electric contact piece is made into described core, and an electric contact piece is made into described sleeve pipe.
16. laser according to claim 1:
Wherein said nano wire comprises vertical heterogeneous structural nano line; With
Wherein said pumping source is a power supply, and wherein electric current flows between the section of described vertical heterogeneous structural nano line.
17. according to the laser of claim 16, wherein said vertical heterogeneous structural nano line is represented p-n junction.
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