JPH01183499A - Production of high-purity znse single crystal and apparatus therefor - Google Patents

Abstract

PURPOSE:To obtain the title single crystal in high efficiency with prevention of impurity contamination, by treating, under specified conditions, the Zn and Se put in a sealed ampul. CONSTITUTION:The raw material section of an ampul constituted of (A) crystal growth section and raw material section of equal large diameter, (B) reserver section of small diameter, and (C) shoulder section for restricting the number of crystal nuclei is packed with both high-purity Zn and Se powder followed by vacuum sealing. Thence, the end of the reserver section is kept at relatively low temperatures (e.g., 20 deg.C) and the rest of the ampul is heated (e.g., to 1,200 deg.C) to synthesize powdery ZnSe and separate excess Zn out at the end of the reserver section. Finally, such a temperature gradient in the ampul is provided that the temperature at the raw material section is the sublimation temperature of ZnSe (e.g., 1,050 deg.C), the temperature of the crystal growth section is the separation temperature of ZnSe crystal and the temperature at the end of the reserver section is such as to keep a specified Zn vapor pressure (e.g., 500 deg.C), thus growing the objective single crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention provides a method for preparing Zn from starting materials Zn and Se in a sealed ampoule.
The present invention relates to a method for producing an nSe single crystal and an apparatus therefor.

(Prior Art) Conventionally, when creating a ZnSe single crystal by a vapor phase transport method, ZnSe is synthesized in advance, stored in an ampoule as a ZnSe powder or polycrystal, and grown as a single crystal while being sublimated and purified.

(Problems to be Solved by the Invention) In the above method, it is first necessary to synthesize ZnSe used as a raw material by the high-pressure Bridgman method or CVD method, and during the synthesis process, impurities from the crucible, outer wall, and even the growth atmosphere are is mixed into the synthesized ZnSe, so this Z
Single crystals grown from nSe were not sufficiently pure. Furthermore, when the ZnSe raw material is transferred from the equipment for synthesizing it to the ampoule, it is exposed to outside air and becomes contaminated. Also,
Since the powdered ZnSe raw material has poor workability, it is difficult to enclose a large amount of the raw material into an ampoule at one time, and as a result, the single crystal obtained is also very small.

The present invention solves the above-mentioned problems and provides a method and apparatus for efficiently producing a high-purity ZnSe single crystal by carrying out everything from ZnSe synthesis to single crystal growth while isolated from the source of contamination. This is what I am trying to do.

(Means for Solving the Problems) The present invention provides (1) a method for producing a ZnSe single crystal in a sealed ampoule, in which a large diameter crystal growth part and a raw material part and a small diameter riser)-1 part and using an ampoule with
After storing Zn and Se in the raw material section and vacuum sealing the ampoule, ZnSe is synthesized by heating the whole with the end of the reservoir section at a relatively low temperature, and excess Zn is precipitated at the end of the reservoir section. Then, a temperature gradient was created in the ampoule so that the raw material part was at the ZnSe sublimation temperature, the crystal growth part was at the ZnSe crystal precipitation temperature, and the end of the reservoir part was at the temperature for maintaining a predetermined Zn vapor pressure. Provide ZnS
(2) A method for producing a ZnSe single crystal from Zn and Se, comprising a closed ampoule and a heating means for forming a temperature gradient within the ampoule. In the apparatus for producing the ampoule, the ampoule is composed of a crystal growth part and a raw material part having the same wide diameter, a small diameter reservoir part, and a constriction part for limiting the number of crystal nuclei attached to the end of the crystal growth part. and a means for tilting the ampoule.
e This is a single crystal production device.

(Function) FIGS. 1 and 2 are diagrams for explaining the present invention, and FIG. 2 shows a state in which starting materials Zn and Se are sealed in an ampoule. The ampoule has a crystal growth section and a raw material section of the same wide diameter, a narrow diameter reservoir, and a constriction provided at the end of the crystal growth section to limit the number of crystal nuclei. The shape of the constriction is, for example, 6 in depth.
~10■, the maximum diameter is 3~6㎜, the diameter of the communicating hole is 1~2■
It is a rotating body.

This ampoule is vacuum-sealed with starting materials Zn and Se as shown in Figure 2, then set in a heating furnace, the end of the reservoir section is kept at a relatively low temperature, and the entire ampoule is heated to synthesize powdered ZnSe. , excess Zn is deposited at the end of the reservoir section. Note that the starting materials Zn and Se can also be mixed and filled.

Next, the ampoule is tilted to collect powdered ZnSe in the raw material part as shown in FIG. 1(a), and then the raw material part is
The crystal growth section is set at the Se sublimation temperature, the crystal growth section is set at the ZnSe crystal precipitation temperature, and the end of the reservoir section is set at the Zn Se sublimation temperature in the ampoule.
The temperature shown in Figure 1 (
A Z,nSe single crystal is grown by providing a temperature distribution as shown in b).

In order to obtain a high-quality ZnSe single crystal from powdered R-9e, the crystal growth process is divided into two parts. First, a relatively steep temperature gradient is created between the raw material part and the crystal growth part. - Once the polycrystal is grown, the polycrystal is heated and removed from the ampoule using the difference in thermal expansion coefficient, and the ampoule is tilted and transferred to the raw material section. The Z n S e single crystal is then preferably grown over an extended period of time under a precisely controlled relatively gentle temperature gradient.

In addition, powdery Z deposited in the crystal growth area during the polycrystal growth process
If a relatively small amount of nSe polycrystal is present, the crystal growth area may be heated prior to the single crystal growth step to sublimate and remove the powdered ZnSe polycrystal from the crystal growth area.

In this way, a series of operations from the synthesis of ZnSe to the growth of single crystals can be carried out under a predetermined Zn vapor pressure in a sealed ampoule with a reservoir and a constriction, thereby preventing contamination by impurities from outside the system. There is no need to worry, and operability has been dramatically improved.

(Example) A ZnSe single crystal was created using the quartz ampoule shown in FIG. The ampoule has a raw material part and a crystal growth part with a diameter of 12 mm.
m, the length is 100 mm, and the diameter of the reservoir is 6111 mm.
m1, the length is 120 mm, the depth of the constriction is 7 ms, the maximum diameter is 4+ m, and the diameter of the communicating hole is 1.
I used 5 pieces. The starting material has a purity of 5N (nine).
12g of Zn powder and 1g of 6N (nine) Se powder
Fill the ampoule with 2 g as shown in Figure 2, and
It was evacuated to rr and sealed.

In the synthesis process, by gradually heating and synthesizing from the end,
By suppressing the rapid increase in Se pressure, we finally created a temperature distribution in the ampoule with a temperature distribution of 1200°C in the raw material and crystal growth part and 20°C at the end of the reservoir part and held it for 5 hours to synthesize powdered ZnSe. did.

In the crystal growth process, the maximum temperature of the raw material part is 1050°C, and the temperature gradient to the crystal growth part is 10°C/c.
m, and a temperature distribution with the end of the reservoir portion at 500° C. was formed in the ampoule and maintained for one week. Next, the polycrystal was removed from the ampoule by heating the area around the produced polycrystal and utilizing the difference in thermal expansion coefficient, and the crystal was transferred to the raw material section by tilting the ampoule. After that, the maximum temperature of the raw material part was set to 1000°C, and the temperature gradient to the crystal growth part was set to 1.
A ZnSe single crystal was produced by forming an ampoule with a temperature distribution of 500° C. at the end of the reservoir and holding the ampoule for 2 weeks.

The obtained ZnSe single crystal has a diameter of 10 mm and a length of 1 mm.
It was 0+sw. When the photoluminescence of a chip cut out from this single crystal was measured, it was found that the emission line due to impurities was suppressed to a low level in terms of donor and acceptor properties.

(Effects of the Invention) By adopting the above configuration, the present invention enables a series of operations from synthesis of Zn and Se to generation of ZnSe single crystal to be carried out in a sealed ampoule under controlled Zn vapor pressure. This makes it possible to completely prevent the contamination of impurities from outside the system, and because there is no need to transfer raw materials to another device, operability has been dramatically improved.

As a result, it has become possible to efficiently produce a highly pure ZnSe single crystal.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining the method for producing a ZnSe single crystal according to the present invention. FIG. 1(a) is an explanatory diagram of the crystal growth process, and FIG. 1(b) is an explanatory diagram of the crystal growth process. FIG. 2 is a graph showing the temperature distribution inside the ampoule, and FIG. 2 is a diagram showing the state in which the starting material is sealed.

Claims (3)

[Claims] (1) In a method for producing a ZnSe single crystal in a sealed ampoule, an ampoule having a crystal growth part and a raw material part with the same wide diameter and a small diameter reservoir part is used, Zn and Se are contained in the raw material part, and the ampoule is After vacuum sealing, the end of the reservoir section is kept at a relatively low temperature and the whole is heated.
nSe is synthesized, excess Zn is precipitated at the end of the reservoir part, then the raw material part is brought to the ZnSe sublimation temperature, the crystal growth part is brought to the ZnSe crystal precipitation temperature, and the end of the reservoir part is brought to a predetermined Zn vapor temperature. A method for producing a ZnSe single crystal, which comprises growing the ZnSe single crystal by providing a temperature gradient within the ampoule so as to maintain the temperature. (2) Create a relatively steep temperature gradient between the raw material part and the crystal growth part to grow the ZnSe polycrystal, then heat the crystal growth part to remove the polycrystal from the ampoule, and tilt the ampoule. A method for producing a ZnSe single crystal according to claim 1, characterized in that the polycrystal is transferred to a raw material section, and then the ZnSe single crystal is grown under a gentle temperature gradient. (3) In an apparatus for producing a ZnSe single crystal from Zn and Se, which has a sealed ampoule and a heating means for forming a temperature gradient within the ampoule, the ampoule has a crystal growth part and a raw material part of the same wide diameter. and a narrow reservoir portion and a constriction portion for limiting the number of crystal nuclei attached to the end of the crystal growth portion, and
A ZnSe single crystal production apparatus characterized by comprising means for tilting the ampoule.