JP2000022130A - Manufacture of semiconductor quantum dot device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture semiconductor quantum dots which exhibit high uniformity in high number density. SOLUTION: According to this method of manufacture, at vapor depositing of compound semiconductor quantum dots 9, a material 2 of one family comprising the compound semiconductor and a material 3 of the other family are supplied to the surface of a growing substrate semiconductor 1 at the same time. Then the materials 2 and 6 of one family comprising the compound semiconductor and the material 3 of the other family are supplied separately and alternately. The supply operation to the surface of the growing substrate semiconductor 1 is a step for forming a three-dimensional structure of the order of angstrom in Stransky-Krastanof mode on its surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fabricating a semiconductor quantum dot device, and more particularly to a semiconductor quantum dot characterized by a material supply method for fabricating a highly uniform semiconductor quantum dot structure at high density. The present invention relates to a method for manufacturing an element.

[0002]

2. Description of the Related Art With the progress of semiconductor processes in recent years, nanoscale growth technology and microfabrication technology have been used for manufacturing semiconductor devices. Semiconductor devices utilizing quantum mechanical effects, such as HBTs (heterojunction bipolar transistors) and strained quantum well semiconductor lasers, have been put to practical use, in addition to the improvement in the degree of integration.

In a semiconductor device using such a quantum mechanical effect, for example, a one-dimensional quantum well structure semiconductor laser, an oscillation threshold value and a threshold value due to heat generated due to the movement of many electrons are also considered. It has been pointed out that the limit of the improvement of the temperature characteristic is pointed out. One of the methods for solving this problem is a quantum box (QWB: Quantum) which is a three-dimensional quantum well structure as an ultimate structure utilizing a quantum mechanical effect.
Well Box, that is, adoption of quantum dots has been proposed.

[0004] In addition, in recent years, research has been made energetically to produce a new next-generation semiconductor device using a new structure, such as a proposal of a quantum dot memory utilizing the hole burning effect.

[0005] The quantum dot is a box of potential that is extremely fine enough to give the carrier three-dimensional quantum confinement. In this quantum dot, the state function density of the carrier is discretized as a delta function, and its ground level is obtained. Can have only two carriers, for example, only two electrons in the conduction band, and the excited level can have a plurality of electrons depending on the order of the level. .

[0006] The small size of the quantum dot at the atomic level pushes the miniaturization of electronic devices to the utmost limit, and the quantum mechanical effect inherent to the quantum dot that can be realized can promote the development of new functional elements. For example, by using quantum dots as the active region of a semiconductor laser, there is a merit that the interaction between electrons / holes and light can be made as efficient as possible, and is expected to be a next-generation device technology. is there.

Various techniques have been proposed for fabricating such a semiconductor quantum dot structure. First, an artificially improved processing accuracy which is an extension of the development of microfabrication technology is an electronic device. Lithography using lines, pyramid-shaped crystal tops selectively grown using a mask pattern in a quantum dot structure, tetrahedral recesses formed by etching using a mask pattern A method of manufacturing a quantum dot structure (refer to Japanese Patent Application No. 7-65492, if necessary), a method of utilizing lateral growth at the initial growth on a vicinal substrate,
Alternatively, STM (Scanning Tunnel M)
Atomic manipulation methods that apply the “microscope” technology.

These methods have the advantage that the size (size) of the quantum dots and the position at which they are formed can be arbitrarily controlled because of the common feature that they are processed artificially. The density could not exceed the limit of fine processing technology, and the uniformity was extremely low due to the limit of processing accuracy.

As a new technology which is a breakthrough to solve such limitations, a method of forming quantum dots by themselves has been found, and more specifically, a method in which a lattice-mismatched semiconductor is grown by vapor phase epitaxial growth under certain conditions. A method of self-forming a dimensional fine structure, that is, a quantum dot structure, has been proposed (for example, see Japanese Patent Application No. 7-217466).

[0010] This self-forming method is easy to carry out, and can obtain very high-quality semiconductor quantum dots with extremely high uniformity, high number density, as compared with the case of artificial processing. For example, a semiconductor laser using this self-formed quantum dot has been actually reported, and the possibility of a semiconductor quantum dot device is becoming a reality.

As described above, the breakthrough by the new technology has been obtained, but on the other hand, the problems for practical use have also been clarified. For example, important points for the practical use of the quantum dot semiconductor laser are described. The challenge is to further improve the quantum dot number density and uniformity.

The number density and uniformity of the quantum dots formed by the above-described self-forming method differ depending on the mode of forming the quantum dots, and therefore, the subjects for practical use also differ slightly. Therefore, FIGS. Various self-forming modes will be described with reference to FIG.

First, referring to FIG. 5, Str
The process of forming quantum dots in the anski-Krastanov mode will be described. Referring to FIG. 5 (a), first, a TEG (triethyl gallium) and AsH ₃ are supplied on a GaAs substrate (not shown) by MOVPE (metal-organic chemical vapor deposition).
After forming a GaAs buffer layer 41 of 00 nm (= 0.5 μm), the substrate temperature was set to 500 ° C.
When the As raw material 42 such as H ₃ , the In raw material 43 such as TMI (trimethylindium), and the Ga raw material 44 such as TMG (trimethylgallium) are supplied at the same time, at the beginning of the growth, the InGaAs growth layer becomes elastic based on lattice mismatch. Since the limit is not exceeded, growth is performed two-dimensionally and InGaAs
A wetting layer 45 grows.

Referring to FIG. 5B, when the growth is continued, when the thickness of the InGaAs wetting layer 45 exceeds the elastic limit, the angstrom order as a growth nucleus for forming quantum dots on the surface of the InGaAs wetting layer 45 is obtained. Are discretely formed.

Further, as shown in FIG. 5 (c), when the growth is continued, the three-dimensional nucleus 46 is used as a growth nucleus, and the In composition ratio is relatively large.
The nGaAs quantum dots 47 are formed, and the peripheral portion of the InGaAs quantum dots 47 has a relatively small In composition ratio.
It becomes the nGaAs wetting layer 45.

This is because when the thickness of the InGaAs wetting layer 45 exceeds the elastic limit, the In composition ratio is relatively large.
It is considered that by locally generating the nGaAs quantum dots 47, the strain energy of the whole InGaAs growth layer becomes lower than that in the case where the strain is generated on the entire surface of the InGaAs growth layer, and the crystal becomes crystallographically stable.

This Transki-Krastano
The self-forming method using the v-mode is the most commonly used method at present because of easy fabrication. In this method, a high number density, for example, a number density of up to about 40% in area ratio is obtained. Can be realized.

The second is a so-called Volmer-Webber (Bolmer-Webber) mode, in which quantum dots are formed by starting three-dimensional growth directly without performing two-dimensional growth at the beginning of growth. Yes,
The appearance is such that the InGaAs wetting layer 45 does not exist in the Transki-Krastanov mode.

Although the Volmer-Webber mode is generally considered to occur at a lower temperature than the Transki-Krastanov mode, it is difficult to obtain a good quality quantum dot, and practically little research has been conducted.

Next, a process of forming quantum dots by alternately supplying the raw materials will be described with reference to FIG. First, a GaAs buffer layer 51 having a thickness of 500 nm is formed on a GaAs substrate (not shown) using a MOVPE method, and then an In source material 52 such as TMI is supplied alone to form GaAs. In metal islands 53 are discretely formed on the surface of the buffer layer 51.

Next, referring to FIG. 6B, when the Ga raw material 54 such as TMG is supplied alone,
Ga metal islands 55 are discretely formed on the surface of the GaAs buffer layer 51, and In metal islands 53 have In
And Ga are mixed to form an In + Ga metal island 56.

Next, as shown in FIG. 6 (c), when the As material 57 such as AsH ₃ is supplied alone, the surface is reconstructed (Reconstruction).
n) occurs, an InGaAs quantum dot 59 having a relatively large In composition ratio is formed in the In + Ga metal island 56, and an InGaAs layer 58 having a relatively small In composition ratio is formed in the Ga metal island 55 and its vicinity. By repeating such a cycle several times, a final quantum dot is formed.

The self-forming mode by alternate supply of the raw materials has a two-dimensional structure, that is, a mode in which a portion having a non-uniform composition in the InGaAs layer 58 is three-dimensionally formed as the InGaAs quantum dots 59. It is characterized in that quantum dots with high uniformity can be obtained. The shape of the InGaAs quantum dots 59 has an aspect ratio of 1/2.
And a flat spherical shape close to a spherical shape.

[0024]

However, among the conventional methods for self-forming semiconductor quantum dots, the method of Transki-
In the case of the Krastanov mode, although the number density of the obtained quantum dots is high, there is a problem that the uniformity of the quantum energy is low.

That is, Transki-Krastan
The shape of the quantum dot in the ov mode has an aspect ratio of 1/5.
It is considered that the uniformity of the quantum energy is low because the quantum energy is sensitive to the fluctuation in the thickness direction. For example, the half-width of the light emission by photoluminescence measurement is usually 80%.
It is on the order of meV, and the quantum energy has spread considerably.

On the other hand, in the case of the self-forming mode by alternate supply of the raw materials, there is a problem that the obtained quantum dots have a high uniformity but a low number density. For example, the area ratio is about 10% at the maximum. When a quantum dot semiconductor laser is manufactured by such a self-forming method with a low number density, there is a problem that the optical output cannot be increased.

Accordingly, an object of the present invention is to produce semiconductor quantum dots with high uniformity at a high number density.

FIG. 1 is an explanatory view of the principle configuration of the present invention. Referring to FIG. 1, means for solving the problems in the present invention will be described. In addition, FIG.
FIG. 4 is a diagram schematically illustrating a process of forming a semiconductor quantum dot. See FIG. 1. (1) The present invention provides a method for fabricating a semiconductor quantum dot 9 device, in which a compound semiconductor quantum dot 9 is vapor-grown in a vapor phase, and a raw material 2 of one group and a raw material of the other group constituting the compound semiconductor. 3 are simultaneously supplied to the surface of the base semiconductor 1, and then the raw materials 2 and 6 of one group and the raw material 3 of the other group constituting the compound semiconductor are separately and alternately supplied.

Thus, at the beginning of the growth, Str
anski-Krastanov mode or Volm
After starting local three-dimensional growth in the er-Webber mode, by using an alternate supply method of raw materials, S
transki-Krastanov mode or Vo
By utilizing the high number density of the semiconductor quantum dots 9 which is an advantage of the lmer-Webber mode, and utilizing the high uniformity of the semiconductor quantum dots 9 which is an advantage of the method of alternately supplying the raw materials, a semiconductor having a high uniformity is obtained. The quantum dots 9 can be manufactured with a high number density.

That is, at the beginning of the growth, the wetting layer 4
A three-dimensional structure 4 having a high number density is formed after the growth of the metal, and a metal island 7 having the three-dimensional structure 4 as a nucleus is formed at the beginning of the step of alternately supplying the raw material. Means that the metal island 7 is a semiconductor quantum dot 9
Since the compound semiconductor layer 8 is formed so as to cover the periphery and the surface thereof, a high-quality flat spherical semiconductor quantum dot 9 having a large aspect ratio and a nearly spherical shape is obtained as in the case of the alternate supply method of the raw material. Can be

(2) Further, according to the present invention, in the above (1), the step of simultaneously supplying the raw material 2 of one group and the raw material 3 of the other group constituting the compound semiconductor to the surface of the growth underlying semiconductor 1 comprises: The process is characterized by a step of forming a three-dimensional structure 5 in the order of Angstrom in the Stranky-Clusteroff mode on the surface of the semiconductor substrate 1 to be grown.

As described above, the self-formation mode at the beginning of the growth is defined as Stransky-Clustnov.
By using the (Krastanov) mode, a three-dimensional structure 5 of the angstrom order, which serves as a growth nucleus of the semiconductor quantum dots 9, can be formed with high reproducibility by a simple process with high reproducibility.

(3) Further, according to the present invention, in the above (1) or (2), the raw materials 2 and 6 of one group and the raw material 3 of the other group constituting the compound semiconductor are separately and alternately supplied. In the process, at least one of the raw materials 2 and 6 of one group and the raw material 3 of the other group is composed of a plurality of different homologous raw materials, and the plurality of different homologous raw materials are also supplied separately. Features.

In this way, by supplying a plurality of different materials of the same family individually, highly uniform semiconductor quantum dots 9 can be formed with good reproducibility.

(4) Further, according to the present invention, in any one of the above (1) to (3), the compound semiconductor is a III-V compound semiconductor, and one of the groups constituting the compound semiconductor is
It is a group III element, and the other group is a group V element.

In such a method of manufacturing the semiconductor quantum dots 9, although the kind of the compound semiconductor is not specified, particularly when the compound semiconductor is a III-V group compound semiconductor, a high quality semiconductor quantum dot 9 is produced. It can be formed.

(5) In the present invention, in the above (4), the raw materials 2 and 6 of one group constituting the compound semiconductor are at least In raw materials and the raw material 3 of the other group is an As raw material. It is characterized by.

(6) In the present invention, in the above-mentioned (5), the raw materials 2 and 6 of one group constituting the compound semiconductor are I
In the step of separately and alternately supplying the raw materials 2 and 6 of one group and the raw material 3 of the other group, which are the n raw material and the Ga raw material, and constitute the compound semiconductor, the In raw material, the Ga raw material,
It is characterized in that it is supplied alternately in the order of s raw materials.

(7) In the present invention, in the above (5), the raw materials 2 and 6 of one group constituting the compound semiconductor may be I
In the step of separately and alternately supplying the raw materials 2 and 6 of one group and the raw material 3 of the other group, which are an n raw material and a Ga raw material and constitute a compound semiconductor, an In raw material, an As raw material, a Ga raw material, It is characterized in that As materials are alternately supplied in order.

(8) Further, according to the present invention, in any one of the above (5) to (7), the composition of the quantum dot 9 is
characterized in that it is a _{n x Ga 1-x As (} 0 <x ≦ 1).

As described in the above (5) to (8), in the case of the method of manufacturing the semiconductor quantum dots 9 described above, in particular, In _x G
Semiconductor quantum dot 9 made of a _1-x As (0 <x ≦ 1)
Can be obtained with good reproducibility. In the step of alternately supplying the raw materials, the In raw material, the Ga raw material, and the As raw material are supplied alternately, or the In raw material, the As raw material, the Ga raw material, and the As raw material are supplied alternately. It is desirable.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, basic manufacturing steps of an embodiment of the present invention will be described with reference to FIG. Referring to FIG. 2A, first, TEG and AsH ₃ were supplied on a GaAs substrate (not shown) by MOVPE to form a GaAs buffer layer 11 having a thickness of, for example, 0.5 μm. Then, the TMI 13 and A were grown at a growth temperature of 500 ° C.
Simultaneously supply sH ₃ 12 for 1 ML (monolayer) in terms of InAs. At the beginning of the growth, two-dimensional growth occurs, and the InGaAs wetting layer 14 is formed.

As shown in FIG. 2B, when the thickness of the InGaAs wetting layer 14 exceeds the elastic limit, a three-dimensional nucleus 15 of an Angstrom order is formed on the surface of the InGaAs wetting layer 14 at a relatively high density. Note that up to this point, Transki-Klast
Growth takes place in anov mode.

Next, referring to FIG. 2 (c), with the substrate temperature set to 500 ° C.
, TMIDMEA [trimethylindium dimethyl
Tilamine adduct: Trimethylindium
-Dimethylamine add, molecule
Formula: In (CH_Three) _ThreeN (CH_Three)_Two(C_TwoH_Five)] 1
After supplying 6, TMG 17 is supplied. At this point
In addition, In and Ga adhere with the three-dimensional nucleus 15 as a nucleus.
A metal island 18 of In + Ga is formed.

Next, as shown in FIG.
By supplying H ₃ 12, restructuring occurs on the surface, and InGaAs quantum dots 19 having a relatively large In composition ratio are formed at the metal island 18, and InGa
An InGaAs layer 20 having a relatively small In composition ratio is formed so as to cover the periphery and the surface of the As quantum dot 19,
The InGaAs quantum dots 19 are buried in the InGaAs layer 20, and the shape is the same as in the alternate supply mode of the raw materials.

After repeating such alternate supply cycle for 10 cycles, TEV is again performed using the MOVPE method.
G and AsH ₃ are supplied, and the thickness is, for example, 30 nm.
GaAs layer (not shown) is formed.

In this case, Stran is used for comparison.
InGaAs by ski-Krastanov mode
Quantum dots were also formed. That is, as in the case of the above-described embodiment of the present invention, M
Using the OVPE method, supply TEG and AsH ₃ ,
After forming a GaAs buffer layer having a thickness of 0.5 μm, TMI and AsH were grown at a growth temperature of 500 ° C.
_{3 at the same time} as InML equivalent to 2ML
After forming the As quantum dots, TEG and AsH ₃ are again supplied by using the MOVPE method to form a GaAs layer having a thickness of 30 nm.

The InGaAs quantum dots of the above embodiments and a Transki-Krastan for comparison
Planar TEM of InGaAs quantum dots in ov mode
As a result of observation, no difference in the number density was found between the two, and the number density was approximately 15%. This number density is higher than in the case of only the alternate supply method.

Since there was no difference between the two in the number density itself, the conditions for simultaneous supply, that is,
By selecting the conditions in the i-Krastanov mode process, for example, the growth temperature can be reduced or As
Tertiary butylarsine (TBA) instead of H ₃
It is possible to increase the number density by using, for example.

Next, the uniformity of the InGaAs quantum dots according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a diagram showing the wavelength dependence of the light emission intensity of the InGaAs quantum dots of the present invention measured by photoluminescence. As is clear from the drawing, the light emission half width is about 0.961.
It is about 35 meV centering on eV (12900 °), which is about the same as that in the normal alternating supply mode. On the other hand, in the case of the Transki-Krastanov mode, the emission half width is about 80 meV.
It is clear that it is higher than in the ov mode.

Also, from the emission intensity itself, InGaAs
It is clear that the crystallinity of the quantum dots is good,
Therefore, according to the embodiment of the present invention, without causing deterioration of crystallinity, the size of the semiconductor quantum dots,
In addition, the number density in the plane can be controlled.

Next, a quantum dot semiconductor laser as a specific application example of the embodiment of the present invention will be described with reference to FIG. FIG. 4A is a schematic cross-sectional view of a quantum dot semiconductor laser. First, an n-type GaAs substrate 2 is formed by MOVPE.
A 500 nm thick n-type GaAs buffer layer 2
2, a thickness of 1000 nm n-type In _0.5 Ga _0.5 P clad layer 23, and are successively grown an n-type GaAs layer 24 serving as a base semiconductor layer having a thickness of 100 nm.

Next, after supplying TMI and AsH ₃ for 1 ML in terms of InAs, TMDMEA, TMG,
Then, the quantum dot active layer 25 is formed by an ALE method in which AsH ₃ is alternately supplied for 10 cycles, and then a 100 nm-thick p-type GaAs is again formed by the MOVPE method.
s layer 26, 1000 nm-thick p-type In _0.5 Ga _0.5 P
Cladding layer 27 and 500 nm thick p-type GaAs
A contact layer 28 is formed.

Next, although not shown, n-type GaAs
An n-side electrode is provided on the back surface of the substrate 21 and a p-type GaAs
By providing a p-side electrode on the s-contact layer 28, a quantum dot semiconductor laser is completed.

FIG. 4 (b) FIG. 4 (b) is a diagram schematically showing an enlarged portion within a circle shown by a broken line in FIG. 4 (a). At the beginning of growth
InGaAs in ranki-Krastanov mode
An s wetting layer 29 and a three-dimensional nucleus (not shown) are formed, and finally the InGaAs layer 3 having a relatively small In composition ratio.
1 and the InGaAs quantum dots 30 surrounded by the InGaAs wetting layer 29 and having a relatively large In composition ratio are formed.

The composition ratio of the InGaAs quantum dots 30 can be arbitrarily changed by controlling the supply ratio of the raw materials, and the In composition ratio x is 0 <x ≦
1, preferably in the range of 0.2 <x ≦ 0.7. In that case, the In composition ratio of the InGaAs layer 31 in which the InGaAs quantum dots 30 are formed is InGaAs.
It becomes smaller than the In composition ratio of the s quantum dots 30.

The embodiments of the present invention and the specific applications thereof have been described above, but the present invention is not limited to the configurations described in the embodiments and the specific applications thereof.
Various changes are possible. For example, at the time of simultaneous supply of raw materials at the beginning of growth, only TMI serving as an In source and AsH _{3 serving as an} As source are supplied, but TM serving as a Ga source is supplied.
G may be supplied at the same time.

When the raw materials are alternately supplied, TM
IDMEA, TMG and AsH _ThreeSupply alternately in the order
But TMIDMEA, AsH_Three, TMG, and
AsH_ThreeMay be supplied alternately in the order of
The supply order of DMEA and TMG may be reversed.
You.

In order to increase the number density of quantum dots with good reproducibility at the time of alternate supply of the raw material, an adduct of an organometallic compound is used rather than an organometallic compound bonded to a methyl group having a small molecular weight such as TMI. Although TMIDMEA having a large molecular weight is used, TMI may be used, and another material may be replaced with another material capable of supplying the same element.

In the description of the embodiment of the present invention, the quantum dot is described as an InGaAs quantum dot. However, it is in principle self-evident that the quantum dot may be formed of another III-V compound semiconductor. It is clear that the present invention can be applied to other compound semiconductors such as II-VI compound semiconductors or IV-VI compound semiconductors.

[0060]

According to the present invention, when a semiconductor quantum dot is vapor-phase grown, a raw material is simultaneously supplied at the beginning of growth to form a three-dimensional nucleus with a high number density in a Transki-Krastanov mode. Since the semiconductor quantum dots with high uniformity are formed by using the three-dimensional nuclei with high number density as the growth nuclei by the alternate supply method of the raw materials, the semiconductor quantum dots with high uniformity can be manufactured with high number density. It greatly contributes to the improvement of the performance of the semiconductor element.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a basic configuration of the present invention.

FIG. 2 is an explanatory diagram of a manufacturing process according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram of a light emission half width of a semiconductor quantum dot according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view of a quantum dot semiconductor laser of a specific application example of the embodiment of the present invention.

FIG. 5 is an explanatory diagram of a process of forming semiconductor quantum dots in a Transki-Krastanov mode.

FIG. 6 is an explanatory diagram of a process of forming semiconductor quantum dots by alternately supplying raw materials.

[Explanation of symbols]

1 growth underlying semiconductor 2 One family of material 3 other families of ingredients 4 Wetting layer 5 three-dimensional structure 6 one group material 7 metal island 8 compound semiconductor growth layer 9 a semiconductor quantum dots 11 GaAs buffer layer 12 AsH of ₃ 13 TMI 14 InGaAs wetting layer 15 3-dimensional nuclear 16 TMIDMEA 17 TMG 18 metal island 19 InGaAs quantum dots 20 InGaAs layer 21 n-type GaAs substrate 22 n-type GaAs buffer layer 23 n-type In _0.5 Ga _0.5 P clad layer 24 n-type GaAs layer 25 quantum Dot active layer 26 p-type GaAs layer 27 p-type In _0.5 Ga _0.5 P clad layer 28 p-type GaAs contact layer 29 InGaAs wetting layer 30 InGaAs quantum dots 31 InGaAs layer 41 GaAs buffer layer 42 As raw material 43 In raw material 44 Ga raw material 45 In GaAs wetting layer 46 three-dimensional nucleus 47 InGaAs quantum dots 51 GaAs buffer layer 52 In material 53 In metal island 54 Ga material 55 Ga metal island 56 In + Ga metal island 57 As material 58 InGaAs layer 59 InGaAs quantum dot

Claims (8)

[Claims] When a compound semiconductor quantum dot is vapor-phase grown, a raw material of one group and a raw material of the other group constituting the compound semiconductor are simultaneously supplied to the surface of a growth base semiconductor, and then the compound semiconductor is formed. A method for fabricating a semiconductor quantum dot device, characterized in that a raw material of one group and a raw material of the other group are separately and alternately supplied. 2. The step of simultaneously supplying a raw material of one group and a raw material of the other group constituting the compound semiconductor to the surface of the growth underlying semiconductor, the method comprising the steps of: 2. The method for manufacturing a semiconductor quantum dot device according to claim 1, wherein the method is a step of forming an order three-dimensional structure. 3. In the step of separately and alternately supplying a raw material of one group and a raw material of the other group forming the compound semiconductor, the raw material of one group and the raw material of the other group forming the compound semiconductor are provided. 3. The method according to claim 1, wherein at least one of the materials comprises a plurality of different materials of a similar family, and the plurality of materials of a different family are individually supplied. 4. . 4. The compound semiconductor is a group III-V compound semiconductor, and one group constituting the compound semiconductor is a group III-V compound semiconductor.
4. The method according to claim 1, wherein the other group is a group V element. 5. The method according to claim 1, wherein the other group is a group V element. 5. 5. The fabrication of a semiconductor quantum dot device according to claim 4, wherein the raw material of one group constituting the compound semiconductor is at least an In raw material, and the raw material of the other group is an As raw material. Method. 6. A material of one group constituting the compound semiconductor is an In material and a Ga material, and a material of one group and a material of the other group constituting the compound semiconductor are separately and alternately supplied. 6. The method of manufacturing a semiconductor quantum dot device according to claim 5, wherein in the step, an In material, a Ga material, and an As material are alternately supplied in this order. 7. A raw material of one group forming the compound semiconductor is an In raw material and a Ga raw material, and a raw material of one group and a raw material of the other group forming the compound semiconductor are separately and alternately supplied. In the process, In raw material, As raw material, Ga
6. The method according to claim 5, wherein the raw material and the As raw material are alternately supplied. 8. The composition of the quantum dot is In _x Ga
_The method of manufacturing a semiconductor quantum dot device according to claim 5, wherein _1-x As (0 <x ≦ 1).