WO2007145088A1

WO2007145088A1 - Semiconductor nanoparticle and method for manufacturing same

Info

Publication number: WO2007145088A1
Application number: PCT/JP2007/061179
Authority: WO
Inventors: Mitsuru Sekiguchi; Kazuya Tsukada
Original assignee: Konica Minolta Medical & Graphic, Inc.
Priority date: 2006-06-14
Filing date: 2007-06-01
Publication date: 2007-12-21
Also published as: JPWO2007145088A1

Abstract

Provided is a semiconductor nanoparticle which is larger than conventional core/shell type nanosize semiconductor particles, easy to handle and has a large emission quantity due to a larger emission area, with no emission wavelength change. A method for manufacturing such semiconductor nanoparticle is also provided. The semiconductor nanoparticle has a hollow section at the center, and has a core layer and a shell layer. The thickness of the core layer is 2-10nm. The core layer and the shell layer are formed of different types of semiconductors, and a bandgap of the semiconductor forming the shell layer is larger than that of a crystal forming the core layer.

Description

Specification

Semiconductor nanoparticles and manufacturing method thereof

Technical field

The present invention relates to hollow semiconductor nanoparticles and a method for producing the same.

Background art

[0002] Nano-sized semiconductors such as semiconductor nanoparticles and semiconductor nanorods are nanometer-sized, and thus exhibit quantum size effects such as increased band gap energy and exciton confinement effects. It is known to exhibit good optical characteristics such as light absorption characteristics and light emission characteristics. Therefore, in recent years, studies on various applications such as displays, biomedicals, and optical communication devices have been promoted as phosphors that can only be actively reported on nano-sized semiconductors.

[0003] For example, an organic molecule is one of core Z shell type semiconductor nanoparticles, a Si / SiO type semi-conductor

2 Biological substance labeling agents bound to the surface of conductive nanoparticles have been studied (for example, see Patent Document 1).

[0004] In a conventional core Z-shell nano-sized semiconductor, the emission wavelength is determined by the size of the bandgap, and the band gap is determined by the diameter of the core layer. Since the diameter of the core layer was determined, it was difficult to handle because large particles could not be formed. For example, in the Si example, the band gap is 1.12 eV, but if this is a nanoparticle with a diameter of nm, the band gap is 1.52 eV and emits light of about 830 nm, and the nanoparticle with a diameter of 4 nm is 1 It is 700 nm at 76 eV and 3.3 nm for nanoparticles with a diameter of 3.3 nm. There is an SiO shell layer with a high SU band gap of about 0.5 to 20 nm, 9. OeV, and the hole-electron pair is closed.

2

The conventional light-emitting nanoparticles are formed by the penetration.

Patent Document 1: Japanese Patent Laid-Open No. 2005-172429

Disclosure of the invention

Problems to be solved by the invention

[0005] The object of the present invention is to change the emission wavelength without changing the conventional core Z-shell type nano-size. The present invention provides a semiconductor nanoparticle that can be handled larger than a semiconductor particle and that has a larger light emission region and a larger amount of light emission, and a method for producing the same.

Means for solving the problem

[0006] The object of the present invention is achieved by the following constitution.

[0007] 1. In a semiconductor nanoparticle having a cavity at the center, having a core layer and a shell layer, and having a core layer thickness of 2 to: LOnm, the core layer and the shell layer are different from each other A semiconductor nanoparticle formed of a semiconductor, wherein a band gap of a semiconductor forming the shell layer is larger than a band gap of a crystal forming the core layer.

[0008] 2. The semiconductor nanoparticles as described in 1 above, wherein the hollow portion has a spherical or tube shape having a diameter of 0.7 to 50 nm.

[0009] 3. A method for producing semiconductor nanoparticles, wherein the core layer and the shell layer of the semiconductor nanoparticles described in 1 or 2 are grown using fullerenes or carbon nanotubes as nuclei.

[0010] 4. The method for producing semiconductor nanoparticles as described in 3 above, wherein after the shell layer is formed, the internal carbon component is ashed to form a hollow structure.

[0011] 5. The method for producing a semiconductor nanoparticle according to 4 above, wherein the internal carbon component is ashed by heat treatment.

The invention's effect

[0012] According to the present invention, the light emission wavelength is not changed, and it is easier to handle than the conventional core Z-shell type nano-sized semiconductor particles. Particles and methods for their production can be provided.

Brief Description of Drawings

FIG. 1 is a production process diagram of SiO 2 ZSiZ hollow nanoparticles with fullerene as a nucleus.

FIG. 2 is a production process diagram of SiO 2 ZSiZ hollow nanoparticles with carbon nanotubes as the core.

[0014] 1 Fullerene 2, 27 Si layer

3 SiZ fullerene nanoparticles

4, 24 reaction chamber

5 Vaporizer

6, 26 RF electrode

7 Collector

8, 29 SiO layer

2

9 SiO 2 ZSiZ fullerene nanoparticles

10, 31 SiO 2 ZSiZ hollow nanoparticles

21 Si substrate

22 SiO

2

23 Co nanoparticles

25 carbon nanotubes

28 SiZ carbon nanotube nanoparticles

30 SiO 2 ZSiZ carbon nanotube nanoparticles

BEST MODE FOR CARRYING OUT THE INVENTION

[0015] The present inventors have studied the above-mentioned problems, and form fullerene or carbon nanotubes as cores to form hollow core Z-shell nanoparticles that are larger than conventional ones, or fullerenes or carbon nanotubes in a later step. By forming the hollow core Z-shell nanoparticle with a larger hollow area by ashing the part, the core Z-shell nanoparticle is enlarged, easy to handle, and the emission intensity per unit The inventors have found that large nanoparticles can be obtained and have completed the present invention.

[0016] That is, the present invention relates to a fullerene having a diameter of about Im having a hollow structure of about 0.7 nm with no atomic structure inside or a carbon nanotube having a hollow portion of about 0.7 to 50 nm. : A hollow core Z-shell semiconductor nano-particle that is grown as a core layer and a semiconductor layer having a larger band gap than that of the core layer. The fullerene or carbon nanotube layer may be removed in a later step. [0017] The present invention will be specifically described below.

In the present specification, hollow core Z-shell semiconductor nanoparticles have a substantially spherical shape and a cylindrical shape, and so-called nanowires having a maximum length of several tens / zm. Includes structure.

[0019] The band gap of the crystal is, for example, Katsuzo Kaminishi, Electronic Device Materials, Nihon Rie Press (2002), p. 62, Hiroshi Kobayashi, Luminescence Physics, Asakura Shoten (2000) p. Indicates the value described in .108.

[Hollow core Z-shell semiconductor nanoparticles]

The hollow core Z-shell semiconductor nanoparticles of the present invention are obtained by growing a core layer and a shell layer using a fullerene or carbon nanotube having a hollow structure as a nucleus. The average thickness of the core layer is 2 to: LOnm. Below 2 nm, the structure is a collection of atoms, and a band gap corresponding to the visible light region is generated. This is preferred, and below lOnm, the efficiency of light emission increases dramatically due to the confinement effect of exciton (one electron-hole pair). This is preferable.

[0021] Further, the fullerene or carbon nanotube may be removed by ashing. In the present invention, fullerene or carbon nanotube is used as an example. However, if the substance has a hollow structure, the core layer and the shell layer may be grown using another substance as a nucleus, and the hollow core Z shell Even after the semiconductor nanoparticles are formed, it is possible to remove the material having the hollow structure as a growth nucleus.

[0022] The core layer and the shell layer are formed of different crystals. The crystal needs to be selected so that the band gap of the crystal forming the shell layer is larger than the band gap of the crystal forming the core layer. For example, the core Z shell is SiZSiO,

2

ZnS / CdSe, CdSZZnO, GaPZAlP, etc. are mentioned.

[0023] Since the hollow core Z-shell semiconductor nanoparticles of the present invention are larger than conventional core Z-shell semiconductor nanoparticles, the handling and handling of the light-emitting layer per particle is large! / Because of this, the amount of emitted light is large!

In the present invention, fullerene or carbon nanotube having a hollow interior is used for producing the hollow layer, but other structures having a hollow structure may be used. Hollow structure For example, a hollow Z-shell layer is grown around the carbon black nanotubes, and the carbon black nanotubes are removed by ashing by heat treatment at about 600 ° C. But ヽ.

As an example of a hollow core Z-shell semiconductor nanoparticle manufacturing method, consider an example with fullerene as the core. Plasma using SiH gas is placed on a C60 fullerene of lnm diameter with a hollow structure of about 0.7 nm as the core. A 2-5nm Si layer is grown by CVD, and then SiH gas

If a SiO layer of about 0.5 to 20 nm is grown by plasma CVD using 4 4 and N 2 O gas

twenty two

Good. When fullerenes are to be incinerated, the oxygen remaining in the fullerene reacts with heat treatment at about 600 ° C, or the fullerene surface is partially exposed on the surface of the semiconductor nanoparticles due to defects, etc. Exposed to O plasma at about 200 ° C.

2

Ashing can be performed. When the combination of the core and the Z-shell of the semiconductor nanoparticles is Si / SiO, there is a possibility that Si may be oxidized. Combination of ZnSZCdSe, etc.

2

If so, I don't have to worry about that. In this example, the core Z shell structure forming method is si

Force achieved by CVD method with SiO / SiO structure Reversed micelle method is hot for structures such as CdSeZZnS

2

It is also possible to produce using a soap method.

<Method for Producing Hollow Core Z-Shell Semiconductor Nanoparticles with Carbon Nanotubes as the Core> As a method for producing the hollow core Z-shell semiconductor nanoparticles, for example, considering an example with carbon nanotubes as the core, a Si substrate is formed on the Si substrate. Nanoparticles that serve as catalysts such as Co are arranged, and carbon nanotubes with a hollow structure of several nanometers are grown by thermal CVD such as CH using them as nuclei.

twenty two

. Then, a 2-5nm Si layer is grown by plasma CVD using SiH gas, and then Si

Four

A SiO layer of about 0.5 to 20 nm is grown by plasma CVD using H gas and N 2 O gas.

4 2 2

You can do it. Completed hollow core made by dissolving Co with H SO H O mixed solution etc.

2 4 2 2 Separate Z-shell semiconductor nanoparticles from Si substrate.

[0027] When carbon nanotubes are to be incinerated, the carbon nanotubes are exposed on the Co-removed surface, so heat treatment at about 600 ° C or oxygen at about 200 ° C

2 Ashing can be performed by exposing to zuma. When the combination of the core z-shell of the semiconductor nanoparticles is SiZSiO, there is a possibility that Si may be oxidized. ZnSZCdSe, etc. If it ’s a combination, do n’t worry! In this example, the core Z shell structure forming method is siZ

The power to realize the SiO structure by the CVD method The structure of CdSeZZnS etc.

2

It is also possible to manufacture using a single-chip method.

Example

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

[0029] Example 1

First, C60 fullerene particles having a hollow structure of 0.7 nm are prepared. Fullerenes can be extracted from Susca by the combustion method, and are currently sold by Frontier Carbon Co., Ltd. (see Electronic Materials, January 2003, p34). In Figure 1 of the example, the particles are separated one by one, but they actually become a mass of particles!

First, as shown in FIG. 1 a), fullerene 1 obtained by the above method is dissolved in an organic solvent, and is made into fine droplets by ultrasonic waves using a vaporizer 5. By passing He gas therethrough, vaporization is performed in the vaporizer 5 (fullerene 1 is suspended in He gas), and fullerene 1 is introduced into the reaction chamber 4 of the CVD apparatus as He gas as a carrier. Next, a source gas, SiH, for forming a Si layer is introduced into the reaction chamber 4. Reaction chamber temperature is 400 ° C, pressure is ITo

Four

It is kept at about rr. By applying 300W of power at 13.56MHz from the RF electrode 6, a Si layer 2 of approximately 4 nm was formed. Finally, the SiZ fullerene nanoparticles 3 thus formed are collected by a collector 7 by introducing them into an organic solvent together with He gas. In this way, SiZ fullerene nanoparticles 3 can be obtained.

[0031] Next, as shown in Fig. 1-b), SiZ fullerene nanoparticles 3 are dissolved in an organic solution and vaporized by a carburetor 5 by publishing with He. Introduce fullerene nanoparticles 3 using He gas as a carrier. Next, form a SiO layer in reaction chamber 4.

2 Introduce raw material gas, SiH, N 2 O at a flow ratio of 1: 3. The reaction chamber temperature is 400

4 2

° C and pressure are kept at about lOTorr. By applying 300 W at 13.56 MHz from the RF electrode 6, an SiO layer 8 of about 5 nm was formed on the surface of the SiZ fullerene nanoparticles 3. This

2

Thus, SiO 2 ZZZ fullerene nanoparticles 9 are formed. Finally, in this way

2

The formed SiO 2 / Si / fullerene nanoparticles 9 are collected by a collector 7. [0032] By the above manufacturing method, SiO having a 0.7 nm hollow structure unique to fullerenes.

2 ZSiZ fullerene nanoparticles were formed. 365η for the SiO / Si / fullerene nanoparticles prepared this time

2

The light of m was irradiated, and the emission intensity was examined with a luminance meter. Compared to SiO ZSi nanoparticles with a Si core that emits the same red light with a diameter of about 4 nm, the emission intensity was about 7 times higher. This

2

This is the diameter of the nanoparticles, the thickness of the conventional SiO shell is 5nm

2, 5 for Si core 4 nm nanoparticles

+ 5 + 4 = to 14nm of the, in the nanoparticles of the present invention is 5 + 5 + 4 + 4 + 1 = 19 nm and a large KikuNatsu, since in particular summer significantly from body force 34 nm ³ of Si portions 380 nm ³ it is conceivable that. However, the diameter may increase in the circumferential direction, and the luminous efficiency per unit volume is considered inferior.

[0033] Next, as shown in Fig. L-c), SiO ZSiZ fullerene nanoparticles 9 are dissolved in an organic solution and He

2

Is vaporized in the vaporizer 5 by publishing with SiO 2 in the reaction chamber 4 of the CVD apparatus.

2

SiZ fullerene nanoparticles 9 are introduced using He gas as a carrier. Next, O in reaction chamber 4

2 By introducing and maintaining the temperature at about 600 ° C, the fullerene is sublimated inside or reacted with o remaining inside the fullerene.

2 Co and remove. This

2 sio 2 ZSiZ cavity nanoparticle 10 is formed. Finally, the sio 2 ZSiZ hollow nanoparticles 10 thus formed are collected by the collector 7.

[0034] By the above manufacturing method, SiO having a hollow structure with a fullerene diameter of lnm

2 ZSiZ cavity nanoparticles were formed. The newly fabricated SiO

2 ZSiZ hollow nanoparticles were irradiated with 365nm light, and the luminescence intensity was examined with a luminance meter. The emission intensity was approximately 7.4 times higher than that of SiO ZSi nanoparticles with a Si core diameter of about 4 nm, which emits the same red light. This is a nanoparticle

2

The diameter of the child is 5 nm of the conventional SiO shell thickness

2, 5 + 5 +4 = 1 for 4 nm Si core nanoparticles

To 4nm of the, in the nanoparticles of the present invention 5 + 5 + 4 + 4 + 1 = 19nm and Ri greatly summer Te Contact be because that particular summer significantly from body force 34 nm ³ of Si portions 380 nm ^3. However, since the diameter is increasing in the circumferential direction, the luminous efficiency per unit volume is considered inferior. Since fullerene itself has a small band gap and a small SU, the confinement effect of exciton is impaired on the S fullerene side. For this reason, it was thought that the emission intensity was increased by removing the fullerene. However, in this example, the emission intensity was not increased as expected. This is because the fullerene layer is equivalent to one atomic layer, so its contribution is small. Fullerene is a stable and hard-to-break molecule, and if it contributes to the absorption of light energy, it is thought that it is a force that has an effect.

[0035] Example 2

First, Co nanoparticles 23 are coated on the Si substrate 21 on which 10 nm of SiO 22 is deposited by the coating method.

2

To do. Place this in the reaction chamber 24 made of quartz tube as shown in Fig. 2-a),

2 Pour about 2 cm and keep lOmin. At 850 ° C. As a result, carbon nanotubes 25 having a hollow lOnm wall thickness of 10 nm and a length of several lOOnm can be formed. In this case, the wall of the carbon nanotube consists of several atomic layers of carbon. (Reference: Y. Huh et al., Mater. Res. Soc. Symp. Proc. Vol. 788 (2004) L3. 19)

Next, as shown in FIG. 2B, the substrate with the carbon nanotubes 25 thus obtained is placed in the reaction chamber of the plasma CVD apparatus. Next, a SiH layer is formed in the reaction chamber

Four

Raw material gases, SiH and He, are introduced. The reaction chamber temperature is 400 ° C and the pressure is about ITorr.

Four

Kept at a degree. By applying 300W power at 13.56MHz from the RF electrode 26, a Si layer 27 of about 4nm was formed. Thus, Si / carbon nanotube particles 28 are formed.

[0036] Next, as shown in Fig. 2-c), the flow rate ratio of SiH, NO, the source gas for forming the SiO layer in the reaction chamber of the CVD apparatus, with respect to the substrate to which the SiZ carbon nanotube particles 28 are adhered.

2 4 2

Introduced at 1: 3. The temperature of the reaction chamber is kept at 400 ° C and the pressure is kept at about lOTorr. By applying 300W at 13.56MHz from the RF electrode 26, a SiO layer of about 5nm is formed on the surface of the SiZ carbon nanotube nanoparticle 28.

2 29 was formed. In this way SiO

2 ZSiZ carbon nanotube nanoparticles 30 are formed.

[0037] By the above manufacturing method, SiO having a lOnm hollow structure and a length of lOOnm

2 ZSiZ carbon nanotube nanoparticles were formed. The sio ZSiZ carbon nanochu fabricated this time

2

The nanoparticles were irradiated with 365 nm light, and the emission intensity was examined with a luminance meter. Compared to SiO ZSi nanoparticles that emit the same red light and have a Si core diameter of about 4 nm, about 30 times per particle

2

The emission intensity was shown. This contributes si subvolumes for light emission of the nanoparticles to 34 nm ³ in Sio 2 ZSi nanoparticles, next 6200Nm ³ when the length lOOnm in nanoparticles of the present invention, are for that summer large as about 200 times . However, because the bandgap of carbon nanotubes is small in SU, the confinement effect of exciton is sufficient on one side. There is a fruit and it is thought that the luminous efficiency increased.

Next, as shown in FIG. 2 d), the group to which the SiO ZSiZ carbon nanotube nanoparticles 30 are attached

2

Co nanoparticles are removed by immersing the plate in a 130 ° C H 2 SO—H 2 O mixture. C

2 4 2 2

o Since the surface of the carbon nanotube is exposed from the nanoparticle removal surface, O is lOOsccm

2

By introducing about 300W and applying RF power of about 300W at 200 ° C, the carbon nanotubes react with O to be CO and removed. As a result, SiO ZSiZ hollow nanoparticles 31 are formed.

2 2 2

Made.

[0039] By the above manufacturing method, SiO ZSiZ hollow nanoparticles having a hollow structure of 30 nm can be formed.

2

Came. The newly fabricated SiO ZSiZ hollow nanoparticles were irradiated with 365 nm light and emitted by a luminance meter.

2

The light intensity was examined. SiO ZSi nano that emits the same red light and has a Si core diameter of about 4 nm

The emission intensity was about 50 times per particle compared to 2 particles. This removes the carbon nanotube layer with a small band gap, and sandwiches the Si light emitting layer between the air layer and the SiO layer.

2

This is thought to be because the confinement effect of excitons could be increased.

Claims

The scope of the claims

[1] A semiconductor having a hollow portion in the center, a core layer and a shell layer, the core layer having a thickness of 2 to: LOnm, and the core layer and the shell layer are different semiconductors A semiconductor nanoparticle characterized by having a band gap force of a semiconductor forming the shell layer, which is larger than a band gap of a crystal forming the core layer.

[2] The semiconductor nanoparticle according to claim 1, wherein the hollow portion is spherical or tube-shaped having a diameter of 0.7 to 50 nm.

[3] A semiconductor nanoparticle characterized in that the core layer and the shell layer of the semiconductor nanoparticle according to claim 1 or 2 are grown using fullerene or carbon nanotube as a nucleus. Production method.

[4] The method for producing semiconductor nanoparticles according to claim 3, wherein after the shell layer is formed, the internal carbon component is ashed to form a hollow structure.

[5] The method for producing semiconductor nanoparticles according to claim 4, wherein the internal carbon component is ashed by heat treatment.