JPH05279196A - Production of cadmium manganese tellurium single crystal - Google Patents

Abstract

PURPOSE:To prolong the life of a crucible and improve the single crystal quality, etc., in the growth of a cadmium manganese tellurium single crystal by Bridgman method using a raw material sealed in a crucible by using a raw material produced by reacting Mn with Te. CONSTITUTION:Manganese is made to react with tellurium in a reaction vessel different from a growing crucible. The reaction product of manganese and tellurium is charged together with cadmium into a crucible and sealed under evacuation. A Cd1-xMnxTe single crystal is grown in the crucible by Bridgman method. Since a reaction product of manganese and tellurium is used as the raw material, the reaction of manganese with tellurium does not take place in the growing crucible. Accordingly, the overheating of the molten liquid in the growing crucible by the reaction heat can be prevented to prevent the damage of the inner surface of the growing crucible and prolong the life of the crucible. There is no contamination of the cadmium manganese tellurium single crystal with the constituent component of the growing crucible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a single crystal of cadmium manganese tellurium.

[0002]

2. Description of the Related Art Cd _1-x Mn _x Te single crystal of Cd _1-x Mn _x Te (hereinafter sometimes referred to as Cd _1-x Mn _x Te single crystal) is used for optical communication, optical information recording, etc. It is a Faraday material used as an optical isolator element for preventing return light of a semiconductor laser used in, an optical fiber current sensor element, and the like, and is used in fields of different wavelengths due to different compositions. The single crystal is generally Cd, Mn, Te.
As a raw material, these mixtures are grown by a Bridgman method in a sealed state in a quartz glass growth crucible whose inner surface is coated with carbon and a quartz glass ampoule containing a pyrolithic boron nitride crucible. Manufactured.

[0003]

By the way, in the above-mentioned method for producing a Cd _1-x Mn _x Te-based single crystal body by the Bridgman method, when three members of Cd, Mn, and Te are reacted in a dissolved state,
In particular, the reaction between Mn and Te raises the temperature and damages the inner surface of the growing crucible. For example, when using a quartz glass crucible coated with carbon on the inner surface as a growth crucible, the carbon coated on the inner surface of the growth crucible is peeled off, and Cd _1-x Mn _x Te melt in the growth crucible is It is highly likely that Si reacts with quartz glass during the growth and becomes mixed with Si as an impurity in the crystal to become a polycrystal, and also cracks occur in the single crystal due to cracks in the growth crucible and the growth crucible. May be destroyed and the growth of the single crystal may not be continued.
When a crucible made of Pyrolithec boron nitride is used as a growing crucible, it does not become polycrystallized as in the former case, but it can be used only a few times due to damage to the growing crucible. For example, in Cd _1-x Mn _x Te X = 0.
In the case of 48 compounds, the growth crucible can be used only about 2 to 3 times. Therefore, it is an object of the present invention to address these issues.

[0004]

According to the present invention, a single crystal of Cd _1-x Mn _x Te is grown by the Bridgman method in a state where a raw material of Cd _1-x Mn _x Te is sealed in a growth crucible. In the method for producing a single crystal of cadmium manganese tellurium, as the raw material,
It is characterized by using a raw material obtained by reacting Mn and Te.

[0005]

In the manufacturing method of the present invention, Mn
Since the reaction product obtained by pre-reacting Fe and Te in another reaction vessel different from the growing crucible is adopted as a part or all of the raw material, there is no or no reaction between Mn and Te in the growing crucible. It will be close. Therefore, the melt in the growth crucible does not become as hot as in the conventional case, the carbon coated on the inner surface of the growth crucible is not damaged and peeled off, and the melt and quartz glass do not react with each other. The constituent components of the growing crucible in the crystal do not become a polycrystal together with being mixed as impurities, and also without the occurrence of cracks in the single crystal due to cracks in the growing crucible, the growing crucible It is not destroyed and the single crystal growth cannot be continued. Further, even when the crucible made of Pyrolithec boron nitride is used as the growing crucible, the inner surface of the crucible is less damaged and the life of the growing crucible is improved.
For example, in Cd _1-x Mn _x Te, in the case of a compound of X = 0.48, the life is dramatically improved from about 2 to 3 times to 20 times or more. Therefore, the single crystal becomes a single crystal with high quality and stable optical characteristics without variations.

[0006]

EXAMPLES Examples of the present invention will be shown below. (Example) Four kinds of Cd _1-x Mn _{x of} X = 0.09, 0.13, 0.30 and 0.48 were prepared by using a reaction product of Mn and Te and Cd as raw materials.
A Te single crystal was grown. The reaction products of Mn and Te were formed by general methods such as heat melting under inert gas and arc melting. As the growing crucible, two types of crucibles A and B shown in FIGS. 1 and 2 were used. Both crucibles A and B have a bottom apex angle of 40 degrees, an inner diameter of 16 mm, an outer diameter of 18 mm, and a length of 150 mm. The crucible A is a silica crucible having an inner surface coated with carbon. A crucible A is charged with a predetermined amount of the raw material C, and the upper part of the crucible A is sealed while being evacuated for growth. Further, crucible B is a crucible made of Pyrolitec boron nitride, which has a vertical angle of 40 degrees, an inner diameter of 18.2 mm, and an outer diameter of 20 after containing a predetermined amount of raw material.
It is put in an ampoule D of mm quartz glass, and the upper part of the ampoule D is sealed while being evacuated and is used for growth.

A crucible A containing the raw material C and an ampoule D containing the crucible B containing the raw material C were set in a vertical Bridgman furnace to melt the raw material C, and then a single crystal was formed at a rate of 2 mm / hr. Was trained. For the growth, the high temperature part (upper part of the furnace)
The temperature was set to 100 to 1,120 ° C, the low temperature part (lower part of the furnace) was set to 910 to 930 ° C, and the temperature gradient between these two zones was set to 20 ° C / cm.

Comparative Example: Both crucibles A and B were used in the same manner as in the above-mentioned examples except that Mn, Te and Cd were used alone as raw materials, and the growth was carried out under the same conditions as in the above-mentioned examples. .. However, for those with a large amount of Mn, which has a high reactivity with the crucible, the growth rate was increased.

(Evaluation of Crystallinity) Tables 1 and 2 show the optical characteristics of the single crystals obtained in Examples and Comparative Examples. The optical characteristics are obtained by evaluating the crystallinity by measuring the extinction ratio. Here, the extinction ratio means that a single crystal sample is put between a polarizer and an analyzer in the crossed Nicols state, and the crystallinity is evaluated by the light scattering state. The larger the numerical value of the extinction ratio, the better the crystallinity. In Tables 1 and 2, the following criteria are used.

[0010]

[0011]

[Table 1]

[0012]

[Table 2]

(Discussion) When the carbon-coated silica crucible A is used, as is clear from Table 1,
It can be seen that when the method of the present invention is adopted, the optical properties of the single crystal are remarkably improved. Further, in the case of using the crucible B made of Pyrolithec Boron Nitride, Table 2
As is clear from the above, when the method of the present invention is adopted, the crucible can be used more than 20 times and its life is remarkably improved. It should be noted that the cost of growing a single crystal is reduced due to the improvement of the life of the expensive crucible.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an example of a crucible for carrying out a manufacturing method of the present invention.

FIG. 2 is a vertical cross-sectional view showing another example of a crucible for carrying out the manufacturing method of the present invention.

Claims (1)

[Claims] 1. A method for producing a cadmium manganese tellurium single crystal, which comprises growing a single crystal of Cd _1-x Mn _x Te by a Bridgman method in a state where a raw material of Cd _1-x Mn _x Te is sealed in a growth crucible. 2. The method for producing a cadmium manganese tellurium single crystal according to, wherein a raw material obtained by previously reacting Mn and Te is used as the raw material.