JPH0361638B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for growing high quality GaAs single crystals by vapor phase epitaxial method.

Prior Art and its Problems A halogen transport method is known as a vapor phase epitaxial growth method for GaAs. In this method, a Ga source saturated with As is heated to 800-900℃, and AsCl ₃ and H ₂ are introduced onto the source to inject Ga.
React with the source. Then, by guiding the gas generated by this reaction downstream and supplying it to the substrate surface maintained at a temperature of 700 to 750°C, GaAs crystals are precipitated from the gas phase and epitaxial growth occurs.

By the way, in the crystal growth process, particles adsorbed on the surface migrate on the surface and are incorporated into kinks to form a lattice. Therefore, the energy required to excite adsorption processes and surface reactions at the surface, the energy required to excite surface migration,
Each process requires the energy needed to anchor to a stable point. Conventionally, thermal energy has been used as an energy source for these. Therefore, as mentioned above, the halogen transport method is used.
When growing GaAs, it is necessary to maintain the substrate temperature at 700-750°C. However, as the temperature is raised, vacancies and interstitial atoms become present, and impurities are introduced through autodoping, which is undesirable in terms of growing highly perfect crystals. Therefore, it is necessary to provide excitation energy for each process of crystal growth without increasing the temperature.

OBJECTS OF THE INVENTION The present invention provides a method for vapor phase epitaxial growth of high quality GaAs single crystals.

Structure of the Invention The present invention has the gist as described in the claims, and is directed to the epitaxial growth of a GaAs single crystal by a Ga/AsCl ₃ /H ₂ system halogen transport method. It is characterized by keeping the temperature below 700°C and irradiating light onto the surface of the substrate crystal.

The present invention will be specifically explained below. FIG. 1 shows a schematic diagram of the apparatus used. A Ga source 3 saturated with As and a GaAs crystal substrate 4 are placed at predetermined positions in a quartz reaction tube 2 having a light introduction window 1. The electric furnace 5 heats the Ga source 3 and the substrate 4 to predetermined temperatures. Light from an irradiation light source 6 is irradiated onto the substrate crystal 4 through the light introduction window 1.
GaAs single crystal is epitaxially grown by passing the H ₂ gas through the flow meter 7 and then through the AsCl ₃ bubbler 9 kept at a predetermined temperature by the constant temperature chamber 8 and into the reaction tube 2 .

Using the apparatus shown in Figure 1, the temperature of the AsCl ₃ bubbler was set to 0.
℃, the _H2 gas flow rate was 100ml/min, and the Ga
Growth was performed by keeping the source temperature at 720°C and varying the substrate temperature. At this time, light from a high-pressure mercury lamp was irradiated onto the substrate surface. Figure 2 shows the results of measuring the hole mobility at 77K of the GaAs crystal grown in this way. As the substrate temperature decreases, the mobility decreases rapidly, but the mobility with light irradiation is 10 to 15% higher than that without light irradiation.
% mobility has increased. FIG. 3 shows the mobility at 77K of GaAs crystals grown by irradiating excimer laser light of various wavelengths when the substrate temperature is 650°C. Mobility increases by irradiating with light in the ultraviolet region.

Moreover, FIG. 4 shows a device in which the direction of light introduction is changed to the direction perpendicular to the gas flow direction in the device shown in FIG. 1. Using this device shown in FIG. When I did this, I got exactly the same results.

Furthermore, FIG. 5 shows that in the apparatus shown in FIG. 4,
The structure is such that the light introduction window is drawn out from the reaction tube main body, and it is possible to prevent the irradiated light from being attenuated due to adhesion of reaction products to the light introduction window.

Effects of the Invention As described above, according to the present invention, epitaxial growth of a high quality GaAs single crystal with high mobility is facilitated at a low substrate temperature, and its industrial effects are significant.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing a growth apparatus according to an embodiment of the present invention. Figure 2 shows the dependence of hole mobility on substrate temperature at 77K, and Figure 3 shows the dependence of hole mobility on substrate temperature.
FIG. 3 is a diagram showing the dependence of hole mobility on wavelength of irradiation light at 77K. FIG. 4 is a diagram schematically showing a growth apparatus that can obtain the same effect as in FIG. 1, and FIG. 5 is a diagram showing a modification of FIG. 4. 1...Light introduction window, 2...Quartz reaction tube, 3...
Ga source, 4...GaAs crystal substrate, 5...Electric furnace, 6...Irradiation light source, 7...Flowmeter, 8...Thermostatic chamber, 9...AsCl ₃ bubbler.

Claims (1)

[Claims] 1. AsCl ₃ vapor and hydrogen gas are used as Ga source or
By introducing As onto a Ga source or GaAs solid source saturated with As and causing a reaction, and supplying the gas generated by this reaction to the surface of the substrate crystal installed downstream of the source, the surface of the substrate crystal is When epitaxially growing a GaAs single crystal thereon, the temperature of the substrate crystal is kept below 700°C,
A method for producing a GaAs single crystal, characterized in that the surface of the substrate crystal is irradiated with light. 2. The method for producing a GaAs single crystal according to claim 1, wherein the irradiated light has a wavelength shorter than 400 nm.