JPS605553B2 - Method for producing polycrystalline zinc selenide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for producing a dense and highly pure polycrystalline body with few defects by heating and compressing zinc selenide (hereinafter referred to as ZnSe) polycrystalline body using hot isostatic pressing. It is related to.

ZnSe is a type of so-called Rho group compound semiconductor material, and due to its good infrared transparency, mechanical properties, and thermal properties, it has recently attracted attention as a component for optical components, especially window materials for carbon dioxide lasers. There is.

In this case, it is desired to develop a material with fewer internal defects such as voids and impurities. These defects cause laser light absorption, which in turn leads to deterioration such as overheating or destruction of the window material. ZnSe for laser window materials must have good mechanical properties (strength), and a polycrystalline material with no hardening properties is used.

As a method for manufacturing ZnSe polycrystals, chemical vapor deposition (Chemical Vapor Deposition) is used as a method to obtain large-sized ones (more than several dimensions in diameter and more than several dimensions in thickness), especially for use in laser window materials.
Two types of methods have been put into practical use: an orientation process (hereinafter referred to as CVD method) and a powder hot press method. However, although the former CVD method has good purity, it takes a long time to manufacture large parts, and when the growth rate is increased to shorten the time, columnar crystal growth becomes noticeable and voids are produced. In many cases, the presence of pores is observed, whereas in the latter method, which uses powder hot pressing, there is a problem that not only is there a large amount of impurities mixed in, but pressure is applied only in one direction, resulting in uneven pressure, and pores remain. there were.

In order to solve these problems, the present invention relates to a method of crushing the pores of the polycrystalline body and densifying it using ultra-high pressure using a hot isostatic press (hereinafter referred to as HIP method), and particularly relates to a method of densifying the polycrystalline body by crushing the pores of the polycrystalline body under ultra-high pressure. The present invention aims to improve the method of sealing a processed body and provide a high-purity ZnSe polycrystal.

The HIP method is known as a method for high-density compression processing of various materials in a high-temperature, high-pressure gas atmosphere.

Since this method can apply high temperature and isotropic pressure at the same time, it has conventionally been used mainly for pressurization of metal-based materials and for removing internal defects in cast products and solidified products. When this HIP method is applied to ZnSe polycrystals, the problem is how to encapsulate them into a closed container (capsule). When performing HIP treatment on ZnSe polycrystals, a pressure medium (
H
It is appropriate to understand. However, Ni used in the general formula
Capsules made of metals such as , Mo, stainless steel, and Pt cannot be used because they all react with ZnSe. Therefore, glass capsules with less reactivity are suitable. FIG. 1 shows the steps from encapsulation into a glass capsule to HIP. A shows the state after the workpiece (ZnSe) 2 is charged into the glass capsule 1, the mouth shows the state after vacuum sealing, and C shows the state after HIP processing, with the glass capsule and ZnSe in close contact. This glass capsule must be moderately softened and deformable at the HIP temperature of ZnSe (900-120,000), and Pyrex glass is the most desirable material in terms of softening point, ease of availability, and processability. . However, since this Pyrex glass usually contains a large amount of components such as B03Na20, "these impurities are
There was a problem of contamination of e.

Table 1 shows the composition of Pyrex glass. Table 1 These impurities are removed from the capsule and Zn as shown in Figure 1 after Hm.
Due to direct contact with Se, it diffuses into ZnSe, causing impurity contamination and causing a decrease in light transmittance.

The present invention solves the above problems and provides a method for reducing impurity contamination from the capsule by forming a carbon film on the inner surface of the capsule in HIP of ZnSe polycrystal using a glass capsule. It is. The contents of the present invention will be explained below with reference to the drawings and examples.

FIG. 2 is a sectional view of a capsule after vacuum sealing in an embodiment of the present invention.

In the figure, 2 is a ZnSe polycrystal, and a carbon coating layer 3 shown by a dotted line is formed on the inner surface of the capsule. Third
The figure is an example showing a method of forming a carbon coating layer on a glass capsule in an embodiment of the present invention. In the figure 6
is an A-state 2 grade inert gas and is used as a carrier gas. 7 is a bubbler that uses organic solvents (acetone, alcohol,
Benzene, etc.) 8 is evaporated and fed into the capsule of 5 together with a carrier gas.

The capsule 4 is heated to about 700 to 900 pm in an electric furnace, and a thermal decomposition reaction occurs within the capsule. Unreacted gas and carrier gas are exhausted to 10 through trap 9. It has been found that the carbon coating layer obtained in this manner is highly pure and delicate, and has the effect of preventing impurities from entering through the glass capsule during HIP processing. Carbon itself is non-reactive with ZnSe and glass capsules and does not cause impurity contamination. In addition, since it is thin and has a thickness of 1 French to several 1 cape, it deforms sufficiently in response to the deformation of the capsule during HIP processing, so the HIP pressure is effectively transmitted to the ZnSe workpiece. . Furthermore, when enclosing the ZnSe polycrystal in the coated capsule, a substance having low reactivity with ZnSe and the capsule (for example, Si02 powder, AI203 powder, carbon powder, etc.) is interposed in the gap between the capsule and the ZnSe polycrystal. In addition, as the material for the glass capsule, alumina silicate glass with a low B203 component may be used in addition to Pyrex glass.

Example 1 Acetone vapor was supplied at 25 cc/min with Ar gas as a carrier gas to the inner surface of a Pyrex glass capsule having a sample loading section with an inner diameter of 25 mm and a height of 5 mm at 700 mm for 1 hour. It was heated to form a carbon coat layer.

This capsule has pores and has a density ratio of 99.6%.
A Ztaka e polycrystal obtained by the VD method was charged, heated at 900 qo for 1 hour, and then vacuum-sealed.

Similarly, a capsule without a carbon cord layer was also vacuum-sealed and used as a comparison sample. These capsules are heated to 1000℃
, HIP work was carried out for 1 hour at 100 atmospheric pressure.

Table 2 shows the specific gravity (density ratio) of the sample before processing and after processing and the analysis results of typical impurity elements using a mass spectrometer. Table 2 (unit: ppm) Example 2 Ethyl alcohol vapor was applied to the inner surface of an alumina-silicate glass capsule having a sample charging part on the side with an inner diameter of 15 ribs and a height of 40 mm, and N2 gas was used as a carrier gas at 50 cc/min.
While supplying the mixture, it was heated at 800° C. for 2 hours to form a carbon coat layer.

A hot-pressed ZnSe polycrystal with pores and a density ratio of 99.2% was placed in this capsule.
1 at q0. After heating and vacuuming for an hour, it was sealed in a vacuum.

Similarly, a capsule without a carbon coat layer was also vacuum-sealed and used as a comparison sample. 1100q of these capsules
o, HIP processing was performed for 2 hours at 150 pressure.
The specific gravity (density ratio) of the sample before processing and after processing and the analysis results of typical impurity elements by the mass spectrometer are displayed in a third display.
Table 3 (unit: m) Example 3 While supplying 30 cc'min of acetone vapor with N2 gas as a carrier gas to the inner surface of a Pyrex glass capsule having an inner diameter of 25 ribs and a mosquito sample cutout of 5 mm in height. , 750 oo for 1 hour to form a carbon coat layer.

This capsule contains ZnS with a density ratio of 80% and has holes.
e The powder molded body was charged, heated and evacuated at 900 qo for 1 hour, and then vacuum sealed.

Similarly, a capsule without a carbon coat layer was also vacuum-sealed and used as a comparison sample. This capsule at 1200 pm
, machi P processing was performed for 3 hours at 200 atmospheric pressure.

Table 4 shows the specific gravity (density ratio) of the sample before processing and after processing, and the analysis results of typical impurity elements using a mass spectrometer. Table 4 (unit: ppm) As described above, the present invention provides a method for converting ZnSe polycrystals into HI
In the method of removing internal defects by P treatment, the inner surface of the capsule is heated by thermal decomposition of an organic solvent.
Since a carbon film is formed, there is an advantage that impurity contamination from the glass capsule can be reduced.

[Brief explanation of the drawing]

Figure 1 A, mouth, and C are from sealing in the glass capsule to the mark P.
The capsule shapes up to the process are shown in order. FIG. 2 is a longitudinal cross-sectional view showing an example of a sealed capsule structure in an embodiment of the present invention. 1: Capsule, 2: Workpiece (ZnSe polycrystal), 3: Carbon coat layer. FIG. 3 is a diagram showing a method of carbon coating the inner surface of a capsule in an embodiment of the present invention. 4: Electric furnace, 5: Capsule, 6: Carrier gas (Ar)
, 7: Bubbler, 8: Organic solvent, 9: Trap, 10:
exhaust. Oh figure 2 figure power 3 figure

Claims (1)

[Claims] 1. In a method of heating and compressing zinc selenide polycrystals using hot isostatic pressing to remove internal defects, a glass capsule is used as a sealed container to enclose the polycrystalline body, and the inner surface of the capsule is coated with acetone, ethyl alcohol, etc. 1. A method for producing polycrystalline zinc selenide, which comprises forming a carbon film in advance by a thermal decomposition method using an organic solvent, and then enclosing the polycrystal and heating and compressing it.