JPH0369880B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a method for producing - group compounds (ZnS, ZnSe, etc.) using a chemical transport method using halogen (halogen transport method) or a sublimation recrystallization method (sublimation method). Concerning bulk single crystal growth methods.

(Prior art) - group compounds such as ZnS and ZnSe are useful semiconductors as photoelectric conversion materials in the visible short wavelength (green/blue) to ultraviolet range because their energy band gap corresponds to the ultraviolet to blue region. Blue light-emitting diode materials, including SiC, GaN, etc., which have not yet been realized as fully practical devices, are essentially capable of high-efficiency light emission. Today, as visible light-emitting diodes play an increasingly important role in industries such as home appliances, industrial equipment, and information equipment, the growth of high-quality crystals of these - group compounds and the realization of devices have enormous industrial significance. have

As shown schematically in Figure 2 A and B, ZnS,
In the bulk single crystal growth method using the halogen transport method or sublimation method for − group compounds such as ZnSe,
Conventionally, a temperature distribution with a flat part followed by a gradually decreasing natural temperature gradient (5 in Figure 2 A) or a temperature distribution with two defined low and high temperatures T ₁ and T ₂ (2 In a heating furnace having 5) in Figure B, the temperatures of the raw material portion 2 and the seed crystal portion 4 placed in a crystal growth container (ampule) 1 made of quartz are set,
A single crystal 3 is grown from a seed crystal 4 or from the tip of an ampoule. Note that FIGS. 2A and 2B show cases in which a vertical heating furnace and a horizontal heating furnace are used, respectively.

(Problems to be solved by the invention) At the current level of single crystal growth technology using the halogen transport method or sublimation method for group compounds, the front of the growing crystal is not uniquely determined; Growth may proceed simultaneously, or growth may proceed simultaneously on planes with different orientations. Therefore, even when a single crystal is obtained, the shape of the growing crystal depends on slight differences in the shape of the ampoule, slight changes in the preparation conditions, and the effects of convection within the ampoule tube caused by these. Each run presents an uncontrolled shape in which arbitrary planes develop in arbitrary directions, and as a result of this, the single crystal size also decreases to a maximum of 10 to 10 mm.
It remains at around 15mm. In other words, no technology has been established for obtaining crystals of high quality and sufficient size that can be used for device fabrication or single crystal growth substrates. For example, as a substrate for epitaxial growth, except for special uses,
Currently, ZnS, ZnSe, etc., have no choice but to use GaAs, GaP, etc., which are disadvantageous because they contain elements that act as impurities. This means that ZnS,
This has become an extremely important issue in research and development, including current device development, which aims to achieve high purity and low defect density, which are important factors in controlling the physical properties of materials such as ZnSe.

The present invention has been made in view of the above points, and its purpose is to eliminate the limitations and drawbacks of conventional methods in the growth method of - group compounds by halogen transport method and sublimation method in a quartz ampoule,
It is an object of the present invention to provide a method for growing bulk single crystals of high quality, sufficient dimensions, and a controlled shape.

(Means for Solving the Problems) In the vapor phase growth method using a halogen transport method or a sublimation method for single crystal of - group compounds according to the present invention, there are a high temperature section, a narrow crystal growth zone, and a low temperature section in a heating furnace. The temperature difference between the high-temperature part and the low-temperature part is kept small, the crystal growth zone is controlled to a predetermined temperature gradient, and the temperature is adjusted so that the crystal growth front is located within the crystal growth zone. The method is characterized in that the ampoule for crystal growth, in which the raw material is placed at one end, is controlled and moved at a predetermined pulling speed.

(Function) A feature of the single crystal growth method of the present invention is that when growing a bulk single crystal of a - group compound using a halogen transport method and a sublimation method, the temperature distribution in the heating furnace causes the crystal growth portion to have a steep slope. , and the crystal growth ampoule is pulled at a constant speed. More specifically, when growing from a seed crystal placed in a quartz ampoule or generated by natural nucleation, the temperature distribution (slope part ), that is, within a fixed plane that can be considered almost isothermal, and then by moving the ampoule at a fixed or stepwise speed, the crystal growth front can be grown as described above. By passing through a constant temperature point and steadily forming a single crystal in a constant shape regardless of temperature distribution or ampoule shape, it is possible to create crystals of arbitrary length with a cross-sectional surface roughly shaped like that of an ampoule. The goal is to realize a growth method for obtaining bulk single crystals.

(Example) Hereinafter, an example of the present invention will be described with reference to FIG.

A raw material 7 and a seed crystal 9 are filled at both ends of a crystal growth container (ampule) 6 made of quartz (in the halogen transport method, a transport gas is also enclosed). There are a high temperature section (temperature T ₂ ') 11 and a low temperature section (temperature T ₁ ') in the vertical heating furnace.
12 and an intermediate temperature gradient section 13. The temperature of the temperature gradient section 13 is
Set the temperature to grow crystals. In other words,
The temperature gradient section 13 is a crystal growth zone. T ₂ ′ and
The temperature difference ΔT from T ₁ ' should be small, and the temperature gradient section 13 should have a steep gradient ΔT/ΔX of about 5°C/cm or more.
to hold. Then, the ampoule 6 is placed in the high temperature section 1.
Insert into 1. Next, the ampoule 6 is pulled upward at a constant pulling speed v of 0.1 to 20 mm/day, which is constant or changed in steps. seed crystal 9
As the crystal moves upward within the temperature gradient section 13, the crystal grows at a point 14 of the temperature gradient section 13, that is, within a fixed plane that can be considered to be approximately isothermal. This point becomes the crystal growth front 8A. In other words, the crystal growth front 8A is located at one point 14 of the temperature gradient section 13.
control so that it is always located at As the ampoule 6 is moved upward in this manner, a bulk single crystal 8 having an outer shape approximately equal to the inner peripheral surface of the ampoule 6 and having an arbitrary length grows.

This growth method has the same effect and productivity in terms of controllability of grown crystals whether the heating furnace is vertically arranged or horizontally arranged. Also, move the ampoule and the furnace relative to each other.

By choosing the ampoule diameter and ampoule length practically arbitrarily, and setting the temperature gradient and ampoule drawing speed to predetermined values with the desired amount of filling material, any diameter and length can be obtained under certain steady growth conditions. High quality and homogeneous ZnS, ZnSe, etc. with
Bulk single crystals of group compounds can be grown with high productivity.

(Effects of the Invention) The present invention makes it possible to supply device crystals and epitaxial substrate crystals of - group compounds.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the growth method using the halogen transport method or sublimation method of the present invention. FIGS. 2A and 2B are schematic diagrams of conventional growth methods used for crystal growth by a halogen transport method and a sublimation method, respectively. 6... Ampoule for crystal growth, 7... Raw material, 8... Growing crystal, 9... Seed crystal, 10... Temperature distribution, 11... High temperature section, 12... Low temperature section, 13... Temperature gradient section.

Claims (1)

[Claims] In the vapor phase growth method using the halogen transport method or sublimation method for single crystals of 1- group compounds, a temperature distribution consisting of a high temperature zone, a narrow crystal growth zone, and a low temperature zone is realized in the heating furnace, and the high temperature zone and the low temperature zone are separated. For crystal growth, the temperature difference is kept small, the above-mentioned crystal growth zone is controlled to a predetermined temperature gradient, the temperature is controlled so that the crystal growth front is located within the above-mentioned crystal growth zone, and the raw material is placed at one end. A method for growing single crystals of - group compounds, which is characterized by moving an ampoule while controlling it at a predetermined pulling speed.