JPH0831419B2 - Method for producing compound semiconductor single crystal on single crystal silicon substrate - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to a compound semiconductor (Ga _1-x Al _x ) _1-y In _y N (0 ≦ x ≦ 1,0) on a single crystal silicon substrate.
≦ y ≦ 1) The present invention relates to a method for producing a single crystal layer.

[0002]

2. Description of the Related Art (Ga _1-x Al _x ) _1-y In _y N (0 ≦ x ≦
1, 0 ≤ y ≤ 1) Crystal is a direct transition type semiconductor with a light wavelength corresponding to the energy band gap at room temperature in the 200 to 700 nm band, especially for light emitting and receiving elements in the visible short wavelength and ultraviolet region. Expected as a material. (Ga _1-x
Since the equilibrium vapor pressure of nitrogen (N), which is a constituent element, of Al _x ) _1-y In _y N crystal is extremely high near the growth temperature, it is not easy to prepare a bulk crystal. Therefore, at present, single crystal production is performed by heteroepitaxial growth using a heterogeneous crystal as a substrate.

The conditions required for a (Ga _1-x Al _x ) _1-y In _y N crystal production substrate are (1) a high melting point (at least 1000 ° C. or higher), and (2) chemical stability. thing,
It is desirable that (3) the crystal quality is excellent, (4) the difference in lattice constant is small, (5) easy to obtain, and (6) the substrate is large. Further, in the case of manufacturing an element that operates electrically, it is desirable that (7) the electric characteristics be easily controlled, particularly that the resistance be low. No crystals satisfy all of these conditions. The most widely used substrate at present is sapphire satisfying (1) (2) (3) (5) (6). Sapphire and (Ga _1-x Al _x )
_1-y In _y N has a lattice constant difference of 11% or more, which is not desirable from the condition of (4), but the present inventors have (Ga _1-x Al _x ).
_1-y In _y N Thin film AlN (~ 50n) at low temperature (~ 600 ° C) immediately before growth.
m) is deposited and used as a buffer layer to ensure high quality (Ga _1-x A
We have found that it is possible to produce l _x ) _1-y In _y N crystals (Japanese Patent Application No. 60-256806), and we have succeeded in producing high-performance blue and UV LEDs using this technology. There is. However, since sapphire is an insulator and is solid, it has a problem that it is not easy to form an element, particularly an electrode, and it is unsuitable for producing an element that operates by a large current injection.

[0004]

Silicon (Si) is one of the candidates for the substrate to solve this problem. Si can easily obtain a low resistance substrate, has a high melting point, and can easily obtain a large perfect crystal. That is, (1) (2) (3)
The conditions (5), (6) and (7) are satisfied. Moreover, since fine processing is easy, it is easy to fabricate an element that operates by high current injection.

On such a silicon substrate, (Ga _1-x Al _x ) _1-y
The biggest problem in making In _y N crystals is, for example, Ga
There is a large lattice constant difference of about 17% between N and Si, and it has been desired to establish a technique for suppressing the generation of crystal defects based on this difference in lattice constant.

The object of the present invention is expected as a material for visible short wavelength and ultraviolet light emission and light receiving elements (Ga _1-x Al _x ).
It is an object of the present invention to provide a method for obtaining a _1-y In _y N crystal on a single crystal silicon substrate that is inexpensive, has high crystal quality, and can easily have a large area and low resistance.

[0007]

According to the present invention, a single crystal silicon substrate is heated and held in an atmosphere containing at least a hydrocarbon gas, and 3C-Si is formed on the surface of the single crystal silicon substrate.
A thin layer of C is formed as a buffer layer, and a compound semiconductor (Ga _1-x Al _x ) _1-y In _y N (0
≦ x ≦ 1, 0 ≦ y ≦ 1) The present invention relates to a method for producing a compound semiconductor single crystal on a single crystal silicon substrate by growing a single crystal layer. Another object of the present invention is to hold a single crystal silicon substrate in a heated state in an atmosphere composed of a hydrocarbon gas and a carrier gas, and then to hold an atmosphere containing at least a compound containing silicon and a hydrocarbon gas. A compound semiconductor on a single crystal silicon substrate, characterized in that the single crystal silicon substrate is held in a heated state, and thereby the thin layer of 3C-SiC is formed as a buffer layer on the surface of the single crystal silicon substrate. A method for producing a single crystal is provided. Still another object of the present invention is to hold a single crystal silicon substrate in a heated state in an atmosphere containing at least a hydrocarbon gas, and to form a thin layer of 3C-SiC on the surface of the single crystal silicon substrate as a buffer layer. And then, the single crystal silicon substrate is held in a heated state in an atmosphere containing at least an organometallic compound containing aluminum and a hydride of nitrogen, whereby the 3C-S
A thin aluminum nitride layer is formed as a buffer layer on the thin iC layer, and then a compound semiconductor (Ga _1-x Al _x ) _1-y In _y N (0 ≦ x ≦ 1 is formed on the surface of the thin aluminum nitride layer. , 0
≦ y ≦ 1) A method for producing a compound semiconductor single crystal on a single crystal silicon substrate, which comprises growing a single crystal layer.

According to the present invention, (Ga _1-x Al _x ) _1-y In _y N
In the case of producing a single crystal on a silicon substrate, (Ga _1-x A
l _x ) _1-y In _y N Immediately before the single crystal growth, at least a hydrocarbon gas (CnHm: n, m is an integer) was introduced into the growth furnace to form a thin SiC layer on the surface of the silicon substrate, and then CnHm was added. Exhaust.
Preferably, an organometallic compound containing at least Al and a hydride of nitrogen are then introduced into the growth reactor to form a thin layer of AlN, thereby removing SiC and AlN from (Ga _1-x Al _x ) _1-y In.
_{It is used as} a buffer layer of _y N crystal and a silicon substrate. Then, only the supply of the organometallic compound containing Al is temporarily stopped, and the organometallic compound containing Al, the organometallic compound containing Ga, and the organometallic compound containing In corresponding to the required mixed crystal composition are continued. By supplying, (Ga _1-x Al _x ) _1-y In _y N on AlN
Make crystals.

In the embodiment of the present invention, the temperature of the silicon substrate in the case of introducing CnHm into the growth furnace to form a thin SiC layer is preferably in the range of 600 to 1300 ° C. In addition, the temperature of the silicon substrate when forming a SiC by introducing a hydrogen compound, a halogen compound or an alkyl compound of silicon and CnHm into the growth furnace is also preferably in the range of 600 to 1300 ° C. Further, the temperature of the substrate is preferably in the range of 600 to 1300 ° C. when the organic metal compound containing at least Al and the hydride of nitrogen are introduced into the growth furnace to form the AlN thin layer. The present invention is based on the above (Ga _1-x A
l _x ) _1-y In _y N, x includes 0 and 1, and 0 to 1
Within the range, the InN mole fraction y is effective within the range of 0 to 1 inclusive of 0 and 1.

[0010]

The inventors of the present invention used the vapor phase growth method, particularly the organometallic compound as a raw material, on a single crystal silicon substrate having excellent crystallographically excellent characteristics in which the electrical characteristics can be easily controlled. High-quality (Ga _1-x Al
_x ) _1-y In _y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) In order to obtain a single crystal, various methods for treating the surface of a silicon substrate were studied, and the above invention was completed.

(Ga _1-x Al _x ) _1-y In _y N on a silicon substrate
The biggest problem in the growth of Si was that there was an extremely large difference in lattice constant of 17% when comparing GaN and Si, for example. In fact, even if GaN was grown directly on a silicon substrate, it was polycrystallized, or even if it was a single crystal, it grew into a hexagonal columnar island shape, making it difficult to produce a high-quality single crystal with good flatness. . In addition, the reverse polarity region (Anti Phase Bounda
The existence of (ry: APB) was also a problem. Therefore, the present inventors considered that some kind of buffer layer is necessary, and examined various crystals, and confirmed that 3C-SiC was the best. As can be seen from Table 1, the difference in lattice constant between SiC and nitride, especially AlN, is extremely small at 0.94%. Moreover, 3C-SiC is (111)
Shibahara reported that the generation of APB can also be controlled by using polar planes such as (100) and (100) planes, and by controlling the atomic steps on the substrate surface (Kyoto University PhD thesis 1987).

Table 1 Lattice constant and difference of lattice constants of Si, SiC and nitride

Further, regarding the growth of nitride crystals on SiC, there has already been a track record in growth using a 6H-SiC (0001) plane as a substrate (eg DK Wickenden et al .: Journal of Crystal Gr.
owth 9: 1971, p. 158). Although 6H-SiC and 3C-SiC have different single crystal structures, the (0001) plane of 6H-SiC and the (111) plane of 3C-SiC have exactly the same atomic arrangement on the outermost surface, so 3C-SiC ( 1
11) High quality (Ga _1-x
An Al _x ) _1-y In _y N single crystal can be obtained. The problem is Si
Although it is a method of obtaining SiC on the substrate, it has already been
It has been reported that 3C-SiC is formed on the surface by keeping the substrate at a high temperature, for example, about 1100 ° C and supplying CnHm, and by using it as a buffer layer, high quality 3C-SiC can be obtained. (For example, IEEE Transaction of Electron Dei
ces ED -28, 1981, p. 1235). That is, it is difficult to obtain 6H-SiC on a single crystal silicon substrate, but it is relatively easy to obtain 3C-SiC.

As in the present invention, by growing (Ga _1-x Al _x ) _1-y In _y N on a silicon substrate using 3C-SiC as a buffer layer, the quality is improved as compared with that directly grown. It is possible to obtain excellent crystals of. Furthermore, 3C-SiC and (Ga _1-x Al _x )
By inserting the AlN thin film as a buffer layer between the _1-y an In _y N _{crystal, (Ga 1-x Al x} ) 1-y In crystallinity and surface flatness of _y N crystal is extremely improved, the sapphire substrate (Ga _1-x Al _x ) _1-y In _y with the same quality as when grown on top
N crystals can be obtained. According to the present invention (Ga _1-x A
l _x ) _1-y In _y N crystals can be obtained at low cost. In addition, the microfabrication of the device becomes easy, and the device that injects a large current, especially the semiconductor laser diode, can be easily manufactured.

[0015]

EXAMPLES Hereinafter, (Ga _1-x Al on a Si substrate according to the present invention will be described.
An example of a method for producing a _x ) _1-y In _y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) single crystal will be described. However, the examples described below merely illustrate the method of the present invention and do not limit the present invention. Fabrication of SiC, AlN buffer layer and (Ga
_{A 1-x} Al _x ) _1-y In _y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) single crystal was prepared by using a normal lateral compound semiconductor growth apparatus. The growth procedure is shown below. First, a crystal growth substrate, that is, a single crystal silicon substrate ((111) plane was used in the experiment) was organically washed, and then a surface oxide was removed by a hydrofluoric acid-based etchant, and the crystal growth portion was set. After evacuation of the growth furnace,
Hydrogen and for example acetylene (C ₂ H ₂ ) are supplied, for example 1200
The temperature was raised to about ° C. As a result, 3C-SiC was formed on the silicon substrate. 3C-SiC when substrate temperature is below 600 ° C
Has poor crystallinity and grows on it (Ga _1-x Al _x ) _1-y
In _y N has poor crystallinity. In addition, since quartz is used for the growth furnace in this growth apparatus and its softening point is 1300 ° C, it was difficult to perform experiments at higher temperatures.

Thereafter, silane (SiH ₄ ) and C ₂ H ₂ are introduced to further grow 3C-SiC, or proceed to the next process,
The growth furnace was once evacuated to remove excess gas.
Next, hydrogen is supplied to the growth furnace to raise the substrate temperature to, for example, 600 ° C
(Within the range of 600 to 1300 ° C), for example, trimethylaluminum (TMA) and ammonia (NH ₃ ) are introduced into the growth apparatus, and an AlN thin film with a thickness of 5 nm to 100 nm is applied to 3C-S.
Formed on iC. If the substrate temperature during AlN thin layer formation is lower than 600 ℃, it grows on it (Ga _1-x Al _x ) _1-y In _y
N 2 was polycrystallized. Also, for the convenience of the device as described above,
Experiments could not be performed above 1300 ° C. Moreover, the flatness of (Ga _1-x Al _x ) _1-y In _y N was poor when the AlN buffer layer was not used. If the AlN buffer layer was thicker than 100 nm, an insulating layer was formed when the device was manufactured, and the electrical characteristics deteriorated.

The buffer layer manufacturing process is as described above. After this, as in the case of forming on sapphire, for example, the substrate temperature was set to 1040 ° C., and trimethylgallium (TMG) and NH ₃
Was supplied to grow GaN. When growing a mixed crystal, TMG, TMA and trimethylindium (TMI) were supplied in an amount corresponding to the composition of the mixed crystal. (Ga _1-x Al _x ) _1-y In
_{After y} N reached the desired growth film thickness, the supply of TMG, TMA, and TMI was stopped and the temperature was lowered. After the substrate temperature fell below 600 ° C, the supply of ammonia was stopped and the temperature dropped to about room temperature. When taken out from the growth device.

Further, a light emitting device was manufactured by using the method of the present invention. According to the present invention, the organometallic compound vapor phase epitaxy method, which is excellent in mass productivity and film thickness controllability, is used, and in particular, a light emitting element is easily manufactured. As shown in FIG. 1, low resistance n
Type 3C-SiC thin layer 2 and Al
After forming the N thin layer 3, undoped or Si-doped n-type
The GaN layer 4 was grown. Subsequently, after growing the Mg-doped GaN layer 5, the structure is taken out of the growth furnace and subjected to low-acceleration electron beam irradiation treatment (see Japanese Patent Application No. 2-2614), and Mg-doped Ga
The N layer 5 was partially made p-type to form a p-type GaN layer 6.
Next, metal electrodes 7A and 7B were vapor-deposited on the back surface of the silicon substrate 1 and the p-type Mg-doped GaN layer 6, respectively, and lead wires 8A and 8B were connected to each of them to form a light emitting diode.
By applying bias with the silicon substrate side being negative and the Mg-doped p-type GaN layer side being positive, blue and ultraviolet light emission could be confirmed at room temperature from a voltage of about 3.5V.

[0019]

As described above, according to the present invention, the crystallinity and the surface flatness are extremely excellent (Ga _1-x Al _x ) _1-y In _y
N 2 single crystal can be produced. Therefore, the present invention
In particular, it is an indispensable technology for practical application of visible short wavelength light emitting devices and near-ultraviolet light emitting devices.

[Brief description of drawings]

FIG. 1 shows (Ga _1-x Al _x ) _1-y In _y N (0 ≦ x ≦ 1, 0 ≦ y ≦ produced on a single crystal silicon substrate by using the present invention.
1) A schematic configuration diagram of a light emitting diode.

[Explanation of symbols]

1 n-type Si (111) plane substrate 2 3C-SiC buffer layer 3 AlN buffer layer 4 undoped or Si-doped n-type (Ga _1-x Al _x ) _1-y In _y N single crystal layer 5 Mg-doped high resistance (Ga _1-x Al _x ) _1-y In _y N single crystal layer 6 Mg-doped p-type (Ga _1-x Al _x ) _1-y In _y N single crystal layer 7A, 7B treated with low-energy electron beam 7A, 7B 8A, 8B lead wire

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 33/00 C

Claims (3)

[Claims] 1. A single crystal silicon substrate is kept heated in an atmosphere containing at least a hydrocarbon gas, and a thin layer of 3C—SiC is formed as a buffer layer on the surface of the single crystal silicon substrate. On top of a thin layer of SiC, a compound semiconductor (Ga _1-x
Al _x ) _1-y In _y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) A method for producing a compound semiconductor single crystal on a single crystal silicon substrate, which comprises growing a single crystal layer. 2. A single crystal silicon substrate is held in a heated state in an atmosphere consisting of a hydrocarbon gas and a carrier gas, and then the single crystal silicon is placed in an atmosphere containing at least a compound containing silicon and a hydrocarbon gas. The substrate is held in a heated state, so that the 3C-Si is formed on the surface of the single crystal silicon substrate.
A method for producing a compound semiconductor single crystal on a single crystal silicon substrate, which comprises forming a thin layer of C as a buffer layer. 3. A single crystal silicon substrate is heated and held in an atmosphere containing at least a hydrocarbon gas to form a thin layer of 3C—SiC as a buffer layer on the surface of the single crystal silicon substrate, and then aluminum is added. The single crystal silicon substrate is held in a heated state in an atmosphere containing at least an organometallic compound and a hydride of nitrogen contained therein, thereby forming an aluminum nitride thin layer as a buffer layer on the 3C-SiC thin layer. Then, the compound semiconductor (Ga _1-x Al _x ) _1-y In _y N (0 ≦ x ≦ 1, 0 ≦ y ≦
1) A method for producing a compound semiconductor single crystal on a single crystal silicon substrate, which comprises growing a single crystal layer.