Production method for compound semiconductor single crystal

Abstract

A production method for a compound semiconductor single crystal by means of a liquid encapsulation Czochralski method in which a semiconductor material and a sealant are stored in a material melt storing unit composed of a bottomed, cylindrical first crucible and a second crucible disposed inside of the first crucible and provided in the bottom thereof with a communication hole with the first crucible, the material storing unit is heated to melt the material, a seed crystal is contacted with the material melt surface that is kept covered with the sealant, and crystal is grown while the seed crystal is pulled up, wherein a heater temperature is so controlled that the diameter of a grown crystal is almost equal to the inner diameter of the second crucible, and crystal is grown with the surface of a growing crystal kept covered with the sealant until crystal growth is completed.

Description

technical field [0001] The present invention relates to a method for producing a compound semiconductor single crystal, and particularly relates to a technique effectively applicable to a method for producing, for example, a ZnTe-based compound semiconductor single crystal by a liquid-encapsulated Czochralski (LEC) method. Background technique [0002] At present, ZnTe-based compound semiconductor single crystal is expected to be applied in pure green light-emitting devices. [0003] Usually, ZnTe-based compound semiconductor single crystals are mostly prepared by the following vapor phase growth method: a raw material ZnTe polycrystal is placed at one end of a quartz ampoule, the polycrystal is heated to sublimate at a temperature near the melting point, and the ZnTe single crystal Precipitates on the substrate on the other side of the quartz ampoule. By this method, a rectangular ZnTe single crystal substrate with a maximum size of about 20mm×20mm can be obtained. Recent...

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Problems solved by technology

[0005] However, in the growth of ZnTe-based compound semiconductor crystals by the vapor phase growth method, it is difficult to add desired impurities during the growth, so it is difficult to control the resistivity of the ZnTe-based compound semiconductor single crystal.

In addition, in the vapor phase growth method, the growth rate of the ZnTe crystal is remarkably slow, so it is difficult to obtain a sufficiently large single crystal, which has the disadvantage of low productivity.

[0006] And, even if the ZnTe compound semiconductor single crystal is grown by the vapor phase growth method, a large substrate of about 20 mm × 20 mm can be manufactured, but the substrate itself becomes very expensive due to low productivity, and it is possible to use a ZnTe compound semiconductor single crystal. The problem of obstacles to component development

[0007] For the above reasons, the ZnTe-based compound semiconductor single crystal is prepared by the vapor phase growth method, which is not practical as an industrial production method.

[0008] On the other hand, ZnTe-based compound semiconductor single crystals can be grown into large crystals by the VB method or VGF method. However, since the crystals are grown by cooling in a state covered with a sealant, the sealant and the growth of the crystals are different. Differences in thermal expansion often lead to crystal cracking

[0009] In addition, like the VB method or VGF method, the LEC method can also add impurities, so it has the advantage of easily controlling the conductivity of the crystal by adding impurities. crystal example

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