CN109244829B - Ge/GeSn heterojunction laser and preparation method thereof - Google Patents

Ge/GeSn heterojunction laser and preparation method thereof Download PDF

Info

Publication number
CN109244829B
CN109244829B CN201811082940.4A CN201811082940A CN109244829B CN 109244829 B CN109244829 B CN 109244829B CN 201811082940 A CN201811082940 A CN 201811082940A CN 109244829 B CN109244829 B CN 109244829B
Authority
CN
China
Prior art keywords
layer
type
gesn
bragg reflector
growing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201811082940.4A
Other languages
Chinese (zh)
Other versions
CN109244829A (en
Inventor
舒斌
张利锋
高玉龙
胡辉勇
王斌
王利明
韩本光
张鹤鸣
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xidian University
Original Assignee
Xidian University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Xidian University filed Critical Xidian University
Priority to CN201811082940.4A priority Critical patent/CN109244829B/en
Publication of CN109244829A publication Critical patent/CN109244829A/en
Application granted granted Critical
Publication of CN109244829B publication Critical patent/CN109244829B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/32—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures
    • H01S5/3223—IV compounds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/12—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers
    • H01S5/125—Distributed Bragg reflector [DBR] lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/3027—IV compounds

Landscapes

  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Semiconductor Lasers (AREA)
  • Lasers (AREA)

Abstract

The invention discloses a Ge/GeSn heterojunction laser and a preparation method thereof. The method comprises the following steps: growing a first Bragg reflector layer on the surface of the substrate; growing a first n-type Ge layer on the surface of the first Bragg reflector layer; growing a second n-type Ge layer on the surface of the first n-type Ge layer; growing a GeSn layer on the surface of the second n-type Ge layer; growing a first p-type Ge layer on the surface of the GeSn layer; growing a second p-type Ge layer on the surface of the first p-type Ge layer; growing a second Bragg reflector layer on the surface of the second p-type Ge layer; etching a first column and a second column on the obtained structure; forming electrodes on the first step and the second step; finally forming the Ge/GeSn heterojunction laser. According to the invention, the GeSn material is adopted to replace the traditional single Ge material, so that the luminous efficiency is improved; the threshold current density is reduced by adopting a P-I-N structure; in addition, the preparation method has simple process.

Description

Ge/GeSn heterojunction laser and preparation method thereof
Technical Field
The invention belongs to the technical field of semiconductors, and particularly relates to a Ge/GeSn heterojunction laser and a preparation method thereof.
Background
As is well known, large-scale integrated circuits on silicon chips exhibit powerful signal processing functions, while fiber optic communication networks around the globe exhibit superior photonic transmission performance. Silicon-based optoelectronic integration combines two advantages of electronic signal processing function and photon transmission performance to realize chip optical interconnection with high speed, low energy consumption and no crosstalk. At present, most of commercialized photoelectric devices adopt III-V semiconductor materials, the process is incompatible with large-scale integration process, the technology of adopting a wafer to be bonded to a silicon wafer is expensive in cost and low in yield, and the photoelectric heterogeneous integration of III-V and chips cannot be widely accepted.
The semiconductor laser has the outstanding characteristics of high energy conversion efficiency, easiness in high-speed current modulation, microminiaturization, simple structure, long service life and the like, and is considered in the application of photoelectric integration. However, due to limitations in processes and the like, there is no suitable on-chip light source. Optical interconnects can reduce Resistive (RC) delay time and power consumption, which is important for on-chip and short-range data communications. Group III-V semiconductor lasers have the best performance to date, but they suffer from high cost, low yield, low integration and unsuitability for mass production, so that group III-V semiconductors take a long time to enter the mainstream silicon manufacturing plant. Group IV materials have been considered as one of the future development directions for light source materials on silicon-based optoelectronic integrated chips. Ge-on-Si lasers are another competitive solution for large scale monolithic integration because they are fully compatible with complementary metal oxide semiconductor field effect transistor (CMOS) technology, which can greatly reduce process complexity, cost and time. In 2007, germanium light emitting devices are predicted, and will be studied starting from tensile strain and high doping levels.
Ge material is the hot research of silicon-based optoelectronic integration due to the characteristics of collimation junction band gap and adjustable energy band in a large range. Band engineering of Ge was originally proposed by the MIT group, who believes that the energy difference between the Γ and L points can be reduced by introducing tensile strain, and that injected electrons from highly doped n-regions can sufficiently fill the Γ energy valleys to facilitate the onset of radiation. The first optically pumped ge laser was first implemented in 2010, and electrically pumped ge lasers were shown in 2012 and 2015. Other types of Ge lasers, e.g. GeSn lasers, Ge QDs lasersOptical devices have been studied recently and these all show the potential of Ge as a Si laser material. But the threshold current density is as high as 280kA/cm2The deviation from the expected value is large; on the other hand, germanium semiconductor material, which belongs to group IV with silicon, is used to fabricate the first transistors in the world, and silicon semiconductors are the dominating element of today's large scale integrated circuits because of the abundance of silicon sources and good silicon oxide surface passivation. Recently, due to the improvement of the technology of epitaxial growth of germanium on silicon, germanium semiconductor materials become a hot spot of research again, and particularly, the laser prepared by the Ge material is the leading edge of research for being used as an on-chip light source.
Jurgen Michel et al, Cambridge university, 2012, studied highly n-doped Si/Ge/n+The Ge electric pumping laser has output power of over 1mw and gain spectrum width of nearly 200 nm; JimengLiu et al, St.Seiyer engineering institute of Dttes, 2012, designed a laser with a Si/Ge/Si structure, with an output wavelength range of 1530-1650nm and an output power of 1 mW; a double-heterojunction Ge laser is designed by Yan Cai and the like in 2013, the laser spectrum with the width of 1520-Si 1700 nanometers is achieved, and meanwhile, the threshold current density is estimated to be 0.53kA/cm2The material gain can reach 1000cm-1(ii) a 2017, JIALIN JIANG et al designed a Ge/SiGe quantum well laser with a threshold current density higher than 1 × 10 under 4% uniaxial tensile stress due to low carrier injection efficiency4kA/cm2The strain Si/Ge/Si is designed by Jianxin Ke et al in 2017, and when the carrier life (tau p, n) is 1ns, the efficiency is ηwp34.8% and threshold current density Jth＝27kA/cm2。
In summary, the technical problems in the prior art include:
1. for a semiconductor laser adopting a Ge material, the Ge material is a direct band gap material, so that the luminous efficiency is not high, and the threshold current density is high, so that the semiconductor laser has a large influence on the performance;
2. when the Fabry-Perot resonant cavity is adopted for the Ge-based laser, the wavelength is large, the number of coating layers of the high-reflection film is large, the process difficulty is high, and the Ge-based laser is easy to fall off.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a Ge/GeSn heterojunction laser and a preparation method thereof. The technical problem to be solved by the invention is realized by the following technical scheme:
the embodiment of the invention provides a preparation method of a Ge/GeSn heterojunction laser, which comprises the following steps:
(1) forming a first Bragg reflector layer on the surface of a substrate;
(2) forming a first n-type Ge layer on the surface of the first Bragg reflector layer;
(3) forming a second n-type Ge layer on the surface of the first n-type Ge layer;
(4) forming a GeSn layer on the surface of the second n-type Ge layer;
(5) forming a first p-type Ge layer on the surface of the GeSn layer;
(6) forming a second p-type Ge layer on the surface of the first p-type Ge layer;
(7) forming a second Bragg reflector layer on the surface of the second p-type Ge layer;
(8) etching the second Bragg reflector layer, the second p-type Ge layer, the first p-type Ge layer, the GeSn layer, the second n-type Ge layer and the first n-type Ge layer in the first region to form a first step; etching the second Bragg reflector layer in the second region to form a second step;
(9) and forming electrodes on the first step and the second step.
In one embodiment of the present invention, step (1) comprises:
alternately growing Si thin film layer and SiO on Si substrate by plasma enhanced chemical vapor deposition2A thin film layer to form the first Bragg mirror layer. 3. The method according to claim 2, wherein the step (2) comprises:
adopting an ultrahigh vacuum chemical vapor deposition method to grow at the temperature of 330-380 ℃ on the first Si/SiO2And growing the first n-type Ge layer on the surface of the thin film layer.
In one embodiment of the present invention, step (3) comprises:
and growing the second n-type Ge layer on the surface of the first n-type Ge layer by adopting an ultrahigh vacuum chemical vapor deposition method at the growth temperature of 200-280 ℃, wherein the doping concentration of the second n-type Ge layer is less than that of the first n-type Ge layer.
In one embodiment of the present invention, step (4) comprises:
and growing a GeSn layer on the surface of the second n-type Ge layer by adopting a molecular beam epitaxy method at the growth temperature of 80-95 ℃, wherein the mass component of Sn in the GeSn is 11-20%.
In one embodiment of the present invention, step (5) comprises:
and growing the first p-type Ge layer on the surface of the GeSn layer by adopting an ultrahigh vacuum chemical vapor deposition method at the growth temperature of 200-280 ℃.
In one embodiment of the present invention, step (6) comprises:
and growing the second p-type Ge layer on the surface of the first p-type Ge layer by adopting an ultrahigh vacuum chemical vapor deposition method at the growth temperature of 330-380 ℃, wherein the doping concentration of the second p-type Ge layer is greater than that of the first p-type Ge layer.
In one embodiment of the present invention, step (7) comprises:
alternating a Si thin film layer and SiO on the surface of the second p-type Ge layer by adopting a plasma enhanced chemical vapor deposition method2A thin film layer to form the second Bragg reflector layer.
In one embodiment of the present invention, step (8) comprises:
in the second Si/SiO2Determining a photoetching area on the surface of the thin film layer by using a first circular mask, etching the second Bragg reflector layer, the second p-type Ge layer, the first p-type Ge layer, the GeSn layer, the second n-type Ge layer and the first n-type Ge layer by adopting an inductively coupled plasma/reactive ion etching method to form a first step, and then etching off the first circular mask;
in the first columnbis-Si/SiO2Defining a photoetching area on the surface of the film layer by using a second circular mask, and etching the second Si/SiO by using inductively coupled plasma/reactive ion etching method2And etching the thin film layer to form a second step.
The embodiment of the invention also provides a Ge/GeSn heterojunction laser, which sequentially comprises the following structures from bottom to top: the semiconductor device comprises a substrate, a first Bragg reflector layer, a first n-type Ge layer, a second n-type Ge layer, a GeSn layer, a first p-type Ge layer, a second p-type Ge layer and a second Bragg reflector layer; the Ge/GeSn heterojunction laser is prepared by the preparation method.
Compared with the prior art, the invention has the beneficial effects that:
1. the efficiency is improved: the structure of the laser adopts the GeSn material and the P-I-N structure, and compared with the traditional heavily doped Ge material laser structure, the efficiency is improved;
2. lowering the threshold current density: the GeSn material of the structure is closer to a direct band gap than a Ge material, and the luminous internal quantum efficiency is higher; the P-I-N structure can better limit the carrier to emit light in the I area, and the limiting factor is improved; the current carriers mostly emit light in the I region, the I region is not doped, non-radiative recombination is reduced, loss coefficients are also reduced, and the threshold current density is reduced through the change;
3. the process is simple: the preparation method does not need processes such as side cleavage coating and the like, and the process is simple;
4. the method is suitable for monolithic optoelectronic integration: the structure of the invention can be compatible with CMOS technology and is suitable for monolithic photoelectric integration.
Drawings
FIG. 1 is a schematic cross-sectional view of a Ge/GeSn heterojunction laser of the present invention;
FIG. 2 is a schematic top view of a Ge/GeSn heterojunction laser according to the present invention;
FIG. 3 is a schematic flow chart of a method for manufacturing a Ge/GeSn heterojunction laser according to the present invention;
fig. 4(a) -fig. 4(h) are schematic diagrams illustrating a method for manufacturing a Ge/GeSn heterojunction laser according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention are not limited thereto.
Example 1:
in order to solve the problems that the conventional Ge-based laser is not high in luminous efficiency, large in threshold current density and difficult in preparation process, the embodiment provides a preparation method of a Ge/GeSn heterojunction laser and the Ge/GeSn heterojunction laser prepared by the method.
Referring to fig. 1 and fig. 2, fig. 1 is a schematic cross-sectional view of a Ge/GeSn heterojunction laser according to the present invention, and fig. 2 is a schematic top view of the Ge/GeSn heterojunction laser according to the present invention. The Ge/GeSn heterojunction laser structure sequentially comprises the following components from bottom to top: the solar cell comprises a substrate 1, a first Bragg reflector layer 2, a first n-type Ge layer 3, a second n-type Ge layer 4, a GeSn layer 5, a first P-type Ge layer 6, a second P-type Ge layer 7 and a second Bragg reflector layer 8; the second bragg reflector layer 8 is cylindrical, the first n-type Ge layer 3, the second n-type Ge layer 4, the GeSn layer 5, the first P-type Ge layer 6 and the second P-type Ge layer 7 are also cylindrical, and the diameter of the cylinder is larger than that of the cylinder formed by the second bragg reflector layer 8 and smaller than that of the first bragg reflector layer.
The substrate 1 of the Ge/GeSn heterojunction laser is preferably a silicon substrate 1, and the silicon substrate 1 is a silicon material on an insulator or a bulk silicon material substrate 1.
The Bragg reflector layer is Si/SiO2A thin film layer of Si and SiO2Periodic structures composed of lower and upper layers alternately arranged, and Si is lower and SiO is in each group of periodic structures2Above. A Distributed Bragg Reflector (DBR) formed of a periodic structure of two materials having a relatively large refractive index alternately arranged is a part of an optical microcavity. The DBR structure is used for replacing the traditional FB resonant cavity, so that the processing is simple, and the monochromaticity of laser is better.
According to the Ge/GeSn heterojunction laser structure, the first N-type Ge layer 3, the second N-type Ge layer 4, the GeSn layer 5, the first P-type Ge layer 6 and the second P-type Ge layer 7 form a P-I-N structure, and the P-I-N structure can better limit the light emission of a current carrier in the I area, so that the limiting factor is improved; the current carriers mostly emit light in the I region, the I region is not doped, non-radiative recombination is reduced, loss coefficients are also reduced, and the threshold current density is reduced through the change; and compared with the traditional heavily doped Ge material laser structure, the efficiency is improved.
According to the Ge/GeSn heterojunction laser structure, a GeSn material is adopted to replace a traditional single Ge material, the stress is changed by adjusting the Sn component so as to meet the requirements of a germanium-tin light source on different wavelengths of light, and the Ge/GeSn heterojunction laser structure has high photoelectric conversion efficiency and light stability.
Referring to fig. 3, fig. 3 is a schematic flow chart of a method for manufacturing a Ge/GeSn heterojunction laser according to the present invention. The method comprises the following steps:
(1) forming a first Bragg reflector layer 2 on the surface of a substrate 1;
(2) forming a first n-type Ge layer 3 on the surface of the first Bragg reflector layer 2;
(3) forming a second n-type Ge layer 4 on the surface of the first n-type Ge layer 3;
(4) forming a GeSn layer 5 on the surface of the second n-type Ge layer 4;
(5) forming a first P-type Ge layer 6 on the surface of the GeSn layer 5;
(6) forming a second P-type Ge layer 7 on the surface of the first P-type Ge layer 6;
(7) forming a second Bragg reflector layer 8 on the surface of the second P-type Ge layer 7;
(8) etching the second Bragg reflector layer, the second p-type Ge layer, the first p-type Ge layer, the GeSn layer, the second n-type Ge layer and the first n-type Ge layer in the first region to form a first step; etching the second Bragg reflector layer in the second area to form a second step;
(9) and forming electrodes on the first step and the second step.
The first region is a region formed by the second Bragg reflector layer, the second p-type Ge layer, the first p-type Ge layer, the GeSn layer, the second n-type Ge layer and the first n-type Ge layer; the second region is a region where the second bragg mirror layer is formed.
For step (1), specific methods that can be employed are:
on a Si substrateGrowing the first Si/SiO by plasma enhanced chemical vapor deposition2A thin film layer; first Si/SiO2The thin film layer is made of Si and SiO2And a periodic structure formed by alternately arranging the upper part and the lower part.
For step (2), specific methods that can be employed are:
in the first Si/SiO2And growing a first n-type Ge layer 3 on the surface of the thin film layer by adopting an ultrahigh vacuum chemical vapor deposition method at the growth temperature of 330-380 ℃.
For step (3), specific methods that can be employed are:
and growing a second n-type Ge layer 4 on the surface of the first n-type Ge layer 3 by adopting an ultrahigh vacuum chemical vapor deposition method at the growth temperature of 200-280 ℃, wherein the doping concentration of the second n-type Ge layer 4 is less than that of the first n-type Ge layer 3.
For step (4), specific methods that can be employed are:
and growing a GeSn layer 5 on the surface of the second n-type Ge layer 4 by adopting a molecular beam epitaxy method at the growth temperature of 80-95 ℃, wherein the mass component of Sn in the GeSn is 11-20%.
For step (5), specific methods that can be employed are:
and growing a first P-type Ge layer 6 on the surface of the GeSn layer 5 by adopting an ultrahigh vacuum chemical vapor deposition method at the growth temperature of 200-280 ℃.
For step (6), specific methods that can be employed are:
and growing a second P-type Ge layer 7 on the surface of the first P-type Ge layer 6 by adopting an ultrahigh vacuum chemical vapor deposition method at the growth temperature of 330-380 ℃, wherein the doping concentration of the second P-type Ge layer 7 is greater than that of the first P-type Ge layer 6.
For step (7), specific methods that can be employed are:
growing a second Si/SiO on the surface of the second P-type Ge layer 7 by adopting a plasma enhanced chemical vapor deposition method2A thin film layer;
second Si/SiO2The thin film layer is made of Si and SiO2And a periodic structure formed by alternately arranging the upper part and the lower part.
For step (8), specific methods that can be employed are:
in the second Si/SiO2Determining a photoetching area on the surface of the thin film layer by using a first circular mask, etching the second Bragg reflector layer, the second p-type Ge layer, the first p-type Ge layer, the GeSn layer, the second n-type Ge layer and the first n-type Ge layer by adopting an inductively coupled plasma/reactive ion etching method to form a first step, and then etching off the first circular mask;
second Si/SiO in the first pillar2Defining a photoetching area on the surface of the film layer by using a second circular mask, and etching the second Si/SiO by using inductively coupled plasma/reactive ion etching method2And etching the thin film layer to form a second step.
According to the embodiment of the invention, the GeSn material is adopted to replace the traditional single Ge material, the stress is changed by adjusting the Sn component to meet the requirements of the germanium-tin light source on different wavelengths of light, and the germanium-tin light source has higher photoelectric conversion efficiency and light stability; the P-I-N structure can better limit the carrier to emit light in the I area, and the limiting factor is improved; the current carriers mostly emit light in the I region, the I region is not doped, non-radiative recombination is reduced, loss coefficients are also reduced, and threshold current density is reduced; in addition, the preparation method of the embodiment does not need processes such as side cleavage coating and the like, and the process is simple.
Example 2:
referring to fig. 4(a) to fig. 4(h) and fig. 1, this embodiment describes the method for manufacturing a Ge/GeSn heterojunction laser and the Ge/GeSn heterojunction laser manufactured by the method of the present invention in detail based on the above embodiments as follows:
step (1), referring to fig. 4(a), selecting a silicon material on an insulator or a bulk silicon material as a substrate, selecting a rectangular substrate 1, and growing a first Si/SiO by Plasma Enhanced Chemical Vapor Deposition (PECVD)2A thin film layer.
The mass flow meter is controlled by a computer to switch so that the reaction gas in the reaction chamber is alternately in SiH4(+ Ar) and O2Thereby decomposing SiH4Alternately feeding deposited polysilicon film and pure oxygen plasma oxidation layer by layerAnd (6) rows.
The substrate 1 temperature was maintained at 250 deg.C, Si and SiO2With Si below, SiO, 143nm and 233nm, respectively2In the above, the Distributed Bragg Reflector (DBR) thus formed is a part of an optical microcavity, and is a periodic structure composed of two materials having a relatively large refractive index alternately arranged, and the optical thickness of each layer of the material is 1/4 of the central reflection wavelength.
Note that, the first Si/SiO2Si/SiO in thin film layer2There may be a plurality of pairs, illustrated as 12 pairs in this embodiment.
Step (2), please refer to FIG. 4(b), the 12 pairs Si/SiO prepared in step (1)2The surface of the thin film layer is grown with a highly doped first n-type Ge layer 3 by low temperature ultra high vacuum chemical vapor deposition (UHV-CVD). The growth temperature is 330-380 ℃, the growth thickness is 200-230 nm, and the doping concentration is 1 x 1018～5×1018cm-3。
The highly doped first n-type Ge layer 3 acts both as a buffer layer to reduce the effect of lattice mismatch from the DBR and to provide a large number of injected electrons.
And (3) as shown in fig. 4(c), growing a second n-type Ge layer 4 with low doping on the surface of the first n-type Ge layer 3 prepared in the step (2) by using a low temperature ultra-high vacuum chemical vapor deposition (UHV-CVD). The growth temperature is 200-280 ℃, the growth thickness is 200-220 nm, and the doping concentration is 5 multiplied by 1017～9×1017cm-3. The doping concentration of the second n-type Ge layer 4 is slightly lower than that of the first n-type Ge layer 3 in order to reduce the optical loss due to auger recombination.
The second N-type Ge layer 4, which is lowly doped, serves as the N region of the laser P-I-N structure, providing a large number of injected electrons.
And (4) with reference to fig. 4(d), growing a GeSn layer 5 on the surface of the second n-type Ge layer 4 prepared in the step (3) by using a low-temperature Molecular Beam Epitaxy (MBE). The growth temperature is 80-95 ℃, the thickness of the GeSn layer 5 is 140-160 nm, the mass component of Sn in the GeSn is 11-20%, and the component of the GeSn layer 5 is Ge0.84Sn0.16。
The GeSn layer 5 is grown by using a low-temperature MBE technology to serve as an active layer, the Sn component is 11-12% to ensure that the GeSn alloy is converted into a direct band gap material, and meanwhile, an ultralow-temperature growth process is adopted to prevent Sn segregation.
And (5) referring to fig. 4(e), growing a first P-type Ge layer 6 with low doping on the surface of the GeSn prepared in the step (4) by ultra-high vacuum chemical vapor deposition (UHV-CVD). The growth temperature is 200-280 ℃, the growth thickness is 200-220 nm, and the doping concentration is 5 multiplied by 1018～2×1019cm-3。
A low-temperature UHV-CVD technique is used to grow a low-doped P-type Ge layer as the P region of the laser P-I-N structure, providing a large number of injected electrons. Its doping concentration is slightly lower than that of the Ge material of step 6) to reduce optical loss due to auger recombination. The doping concentration of the holes is higher than the doping concentration of the Ge material of step 3) considering that it has a lower mobility than the electrons.
And (6) with reference to fig. 4(f), growing a second highly doped P-type Ge layer 7 on the surface of the first P-type Ge layer 6 prepared in the step (5) by ultra-high vacuum chemical vapor deposition (UHV-CVD). The growth temperature is 330-380 ℃, the growth thickness is 200-230 nm, and the doping concentration is 8 multiplied by 1018～5×1019cm-3。
The low temperature UHV-CVD technique is used to grow the first P-type Ge layer 6 with a doping concentration slightly higher than the doping concentration of the highly doped first P-type Ge layer of step (5), which also acts as a buffer layer, reducing the effect of lattice mismatch from the DBR and providing a large number of injected holes.
Step (7), referring to fig. 4(g), growing the second Si/SiO layer on the surface of the second P-type Ge layer 7 prepared in step (6) by using Plasma Enhanced Chemical Vapor Deposition (PECVD)2A thin film layer.
Si/SiO2Distributed Bragg Reflectors (DBRs) are part of the same optical cavity as the DBR of step (1).
Note that the second Si/SiO2Si/SiO in thin film layer2There may be multiple pairs, first Si/SiO2Thin film layer, second Si/SiO2Thin film layer Si/SiO2Can be based on the actual situation of the laserAnd (5) carrying out adaptive adjustment on the conditions. Second Si/SiO in this example2Si/SiO in thin film layer2Illustrated in 6 pairs.
Step (8), referring to fig. 4(h), a photolithography process is used to form a circular silicon nitride film with a radius of 6 μm on the structure prepared in step (6), which is used as a mask for protecting the pattern, a first step is etched, and then the silicon nitride mask is etched away to make the second Si/SiO layer2And etching the thin film layer to the first Ge layer to form a first column.
Then, referring to FIG. 1, on the structure of FIG. 4(h), a photolithography process is performed on the second Si/SiO2Generating a silicon nitride film with the radius of 3 mu m on the surface of the film layer, and etching a second step; finally, the silicon nitride mask is etched away to enable the second Si/SiO2The thin film layer forms a second cylinder. And respectively making contact electrodes on the two etched steps to finish the preparation of the device. The diameter of the first cylinder is smaller than that of the first Si/SiO2The diameter of the thin film layer is larger than that of the second cylinder.
Wherein, the silicon nitride film is grown by LPCVD (low pressure chemical vapor deposition) under the conditions of low pressure and 700 ℃; the formula of the etchant used for ion etching is potassium hydroxide, isopropanol and water in a ratio of 1:2:2, and the etching temperature is 80 ℃; the silicon nitride can be etched by using a mixed solution of hydrofluoric acid and phosphoric acid at 180 ℃.
And (9) forming electrodes on the first step and the second step of the structure obtained in the step (8).
In an embodiment of the invention, the P-I-N structure is composed of Ge/GeSn/Ge. The P-I-N structure can effectively limit carriers in the I region, and because the I region is not doped, non-radiative recombination and photon absorption can be effectively degraded, the carrier injection and light emitting efficiency of the material is improved, and high-efficiency light emitting is facilitated.
In the embodiment of the invention, the upper distributed Bragg reflector is a distributed Bragg reflector alternately composed of 6 pairs of Si/SiO2 materials, the lower distributed Bragg reflector is a distributed Bragg reflector alternately composed of 12 pairs of Si/SiO2 materials, the optical thickness of each layer of material is 1/4 of the central reflection wavelength, and the reflectivity of the Bragg reflector can reach more than 99 percent because the electromagnetic wave with the frequency within the energy gap range cannot penetrate through the material. Meanwhile, the structure has no absorption problem of a metal reflector, and the position of an energy gap can be adjusted by changing the refractive index or the thickness of a material.
In the embodiment of the invention, the etching depth of the cylindrical table-board reaches the upper end of the lower distributed Bragg reflector, and the first Ge layer is not completely etched; the height of the cylindrical mesa was 2.256 μm, and the radius of the cylindrical mesa was 3 μm.
The Ge/GeSn P-I-N laser device and the preparation method thereof provided by the invention can be compatible with a CMOS (complementary metal oxide semiconductor) process, can also meet the requirements of a germanium tin light source on different wavelengths of light by adjusting the Sn component to change the stress, and have higher photoelectric conversion efficiency and light stability. Meanwhile, the FB resonant cavity of the traditional Ge-based laser is replaced by the DBR, so that the processing is simple, the monochromaticity of laser is better, and a specific structure and an implementation scheme are provided for realizing an on-chip light source.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims (10)

1. A preparation method of a Ge/GeSn heterojunction laser is characterized by comprising the following steps:
(1) forming a first Bragg reflector layer on the surface of a substrate;
(2) forming a first n-type Ge layer on the surface of the first Bragg reflector layer;
(3) forming a second n-type Ge layer on the surface of the first n-type Ge layer;
(4) forming a GeSn layer on the surface of the second n-type Ge layer;
(5) forming a first p-type Ge layer on the surface of the GeSn layer;
(6) forming a second p-type Ge layer on the surface of the first p-type Ge layer;
(7) forming a second Bragg reflector layer on the surface of the second p-type Ge layer;
(8) etching the second Bragg reflector layer, the second p-type Ge layer, the first p-type Ge layer, the GeSn layer, the second n-type Ge layer and the first n-type Ge layer in the first region to form a first step; etching the second Bragg reflector layer in the second region to form a second step;
(9) and forming electrodes on the first step and the second step.
2. The method according to claim 1, wherein the step (1) comprises:
alternately growing Si thin film layer and SiO on Si substrate by plasma enhanced chemical vapor deposition2A thin film layer to form the first Bragg mirror layer.
3. The method according to claim 2, wherein the step (2) comprises:
adopting an ultrahigh vacuum chemical vapor deposition method to grow at the temperature of 330-380 ℃ on the first Si/SiO2And growing the first n-type Ge layer on the surface of the thin film layer.
4. The production method according to claim 3, wherein the step (3) includes:
and growing the second n-type Ge layer on the surface of the first n-type Ge layer by adopting an ultrahigh vacuum chemical vapor deposition method at the growth temperature of 200-280 ℃, wherein the doping concentration of the second n-type Ge layer is less than that of the first n-type Ge layer.
5. The method according to claim 1, wherein the step (4) comprises:
and growing a GeSn layer on the surface of the second n-type Ge layer by adopting a molecular beam epitaxy method at the growth temperature of 80-95 ℃, wherein the mass component of Sn in the GeSn is 11-20%.
6. The method according to claim 1, wherein the step (5) comprises:
and growing the first p-type Ge layer on the surface of the GeSn layer by adopting an ultrahigh vacuum chemical vapor deposition method at the growth temperature of 200-280 ℃.
7. The method according to claim 1, wherein the step (6) comprises:
and growing the second p-type Ge layer on the surface of the first p-type Ge layer by adopting an ultrahigh vacuum chemical vapor deposition method at the growth temperature of 330-380 ℃, wherein the doping concentration of the second p-type Ge layer is greater than that of the first p-type Ge layer.
8. The method according to claim 1, wherein the step (7) comprises:
alternating a Si thin film layer and SiO on the surface of the second p-type Ge layer by adopting a plasma enhanced chemical vapor deposition method2A thin film layer to form the second Bragg reflector layer.
9. The method of claim 8, wherein step (8) comprises:
in the second Si/SiO2Determining a photoetching area on the surface of the thin film layer by using a first circular mask, and etching the second Bragg reflector layer, the second p-type Ge layer, the first p-type Ge layer, the GeSn layer, the second n-type Ge layer and the first n-type Ge layer by adopting an inductively coupled plasma/reactive ion etching method to form a first step;
second Si/SiO in the first pillar2Defining a photoetching area on the surface of the film layer by using a second circular mask, and etching the second Si/SiO by using inductively coupled plasma/reactive ion etching method2And etching the thin film layer to form a second step.
10. The Ge/GeSn heterojunction laser is characterized in that the structure of the Ge/GeSn heterojunction laser sequentially comprises from bottom to top: the semiconductor device comprises a substrate, a first Bragg reflector layer, a first n-type Ge layer, a second n-type Ge layer, a GeSn layer, a first p-type Ge layer, a second p-type Ge layer and a second Bragg reflector layer; the Ge/GeSn heterojunction laser is prepared by the preparation method of any one of claims 1 to 9.
CN201811082940.4A 2018-09-17 2018-09-17 Ge/GeSn heterojunction laser and preparation method thereof Active CN109244829B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201811082940.4A CN109244829B (en) 2018-09-17 2018-09-17 Ge/GeSn heterojunction laser and preparation method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201811082940.4A CN109244829B (en) 2018-09-17 2018-09-17 Ge/GeSn heterojunction laser and preparation method thereof

Publications (2)

Publication Number Publication Date
CN109244829A CN109244829A (en) 2019-01-18
CN109244829B true CN109244829B (en) 2020-02-14

Family

ID=65058997

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201811082940.4A Active CN109244829B (en) 2018-09-17 2018-09-17 Ge/GeSn heterojunction laser and preparation method thereof

Country Status (1)

Country Link
CN (1) CN109244829B (en)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6399966B1 (en) * 2000-09-08 2002-06-04 Sharp Kabushiki Kaisha Light emitting nitride semiconductor device, and light emitting apparatus and pickup device using the same
CN1417844A (en) * 2002-12-10 2003-05-14 西安电子科技大学 SiGe/Si Chemical vapor deposition growth process
CN105610047A (en) * 2016-01-01 2016-05-25 西安电子科技大学 GeSn multi-quantum well metal cavity laser and fabrication method thereof
CN106414816A (en) * 2014-06-13 2017-02-15 于利希研究中心 Method for depositing a crystal layer at low temperatures, in particular a photoluminescent IV-IV layer on an IV substrate, and an optoelectronic component having such a layer
CN107785234A (en) * 2016-08-25 2018-03-09 西安电子科技大学 Strain Ge based on Si substrates1‑xSnxThin-film material and preparation method thereof
CN107818978A (en) * 2016-08-25 2018-03-20 西安电子科技大学 Strain GeSn nmos devices and preparation method thereof

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6399966B1 (en) * 2000-09-08 2002-06-04 Sharp Kabushiki Kaisha Light emitting nitride semiconductor device, and light emitting apparatus and pickup device using the same
CN1417844A (en) * 2002-12-10 2003-05-14 西安电子科技大学 SiGe/Si Chemical vapor deposition growth process
CN106414816A (en) * 2014-06-13 2017-02-15 于利希研究中心 Method for depositing a crystal layer at low temperatures, in particular a photoluminescent IV-IV layer on an IV substrate, and an optoelectronic component having such a layer
CN105610047A (en) * 2016-01-01 2016-05-25 西安电子科技大学 GeSn multi-quantum well metal cavity laser and fabrication method thereof
CN107785234A (en) * 2016-08-25 2018-03-09 西安电子科技大学 Strain Ge based on Si substrates1‑xSnxThin-film material and preparation method thereof
CN107818978A (en) * 2016-08-25 2018-03-20 西安电子科技大学 Strain GeSn nmos devices and preparation method thereof

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Direct gap electroluminescence from Si/Ge1−ySnyp-i-nheterostructure diodes;R. Roucka 等;《APPLIED PHYSICS LETTERS》;20110211;第98卷;全文 *
Room-Temperature Electroluminescence From GeSn Light-Emitting Pin Diodes on Si;M. Oehme 等;《IEEE PHOTONICS TECHNOLOGY LETTERS》;20111201;第23卷(第23期);全文 *

Also Published As

Publication number Publication date
CN109244829A (en) 2019-01-18

Similar Documents

Publication Publication Date Title
CN110249491B (en) Laser or LED based on nanowires grown on graphene-type substrates
US10305250B2 (en) III-Nitride nanowire array monolithic photonic integrated circuit on (001)silicon operating at near-infrared wavelengths
CN101689581B (en) Nanowire photodiodes and methods of making nanowire photodiodes
US5674778A (en) Method of manufacturing an optoelectronic circuit including heterojunction bipolar transistor, laser and photodetector
US7596158B2 (en) Method and structure of germanium laser on silicon
US20100032008A1 (en) Zinc oxide multi-junction photovoltaic cells and optoelectronic devices
US8901412B2 (en) Photovoltaic cell
EP2618388B1 (en) Light-emitting diode chip
WO2009023045A2 (en) Nanowire-based opto-electronic devices
JP6159796B2 (en) Nitride semiconductor multilayer mirror and light emitting device using the same
US20190140424A1 (en) Resonant Cavity Strained Group III-V Photodetector And LED On Silicon Substrate And Method To Fabricate Same
JP4825269B2 (en) Method and structure of germanium laser on silicon
KR101957801B1 (en) Flexible Double Junction Solar Cell Device
Chiba et al. Vertical InGaAs nanowire array photodiodes on Si
US20150179857A1 (en) Semiconductor epitaxial structures and semiconductor optoelectronic devices comprising the same
CN113396486A (en) Indium phosphide VCSEL with dielectric DBR
CN113422295A (en) Multi-junction distributed feedback semiconductor laser and preparation method thereof
TWI251270B (en) Carbon doped GaAsSb suitable for use in tunnel junctions of long-wavelength VCSELs
JP5205729B2 (en) Semiconductor laser device and manufacturing method thereof
Nie et al. Quantum-dot resonant-cavity separate absorption, charge, and multiplication avalanche photodiode operating at 1.06 μm
CN109244829B (en) Ge/GeSn heterojunction laser and preparation method thereof
CN217740981U (en) Human eye safe long wavelength VCSEL array chip for laser radar
CN209561861U (en) A kind of GaAs/AIAs/AIAs Bragg reflector laser
CN109449757B (en) SiGe/Ge/SiGe double heterojunection laser and preparation method thereof
Marzban et al. Design of a waveguide-coupled GeSn disk laser

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant