Sumitomo Electric Industries, Limited

Nippon Telegraph and Telephone Corporation

Kazuhisa Matsumoto

Masami Tatsumi

Tomohiro Kawase

Shintaro Miyazawa

Shin-ichi Akai

Hideki Mori

Takashi Shimoda

Masami Sasaki

Katsunosuke Aoyagi

Takashi Suzuki

Shinichi Akai

Hiroshi Morishita

Method of and apparatus for preparing single crystal

A liquid encapsulation Czockralski method for growing a single crystal of a semiconductor compound which comprises: melting a semiconductor compound in the presence of a B.sub.2 O.sub.3 liquid encapsulant to form a two phase liquid; dipping a semiconductor seed crystal into the compound melt covered with the B.sub.2 O.sub.3 encapsulant; growing the crystal from the compound melt by pulling up and rotating the seed crystal; and, cooling the crystal in a cooling zone above a crucible. The cooling zone is maintained at a substantially uniform temperature distribution with a small temperature gradient by using primarily an independently controlled crystal cooling zone heater H3. In addition, an independently controlled melt heater H1 and an independently controlled crystal growing heater H2 are employed. Also, a crystal cooling zone heat shield 11 can be provided to aid in slowly cooling the grown crystal in the substantially uniform temperature distribution. Preferably, a crystal cooling zone heater H3 is employed to control the temperature distribution in the cooling zone. The semiconductor crystals produced by employing the process and apparatus of the invention are substantially crack-free both before and after grinding and cutting. Also the etch pitch density (EPD) of the semiconductor crystal material is significantly lower than conventionally produced material.

Liquid encapsulation method for growing single semiconductor crystals

Gallium phosphide single crystals with low defect density which are manufactured by the liquid encapsulation Czochralski pulling method and which are characterized in that they are doped or not doped with at least one kind of dopant which is electrically active in gallium phosphide and are so doped as to have at least one dopant such as boron or some other strongly reducing impurity which has a reducing activity equal to or greater than that of boron remain in the crystals in a quantity not less than 1.times.10.sup.17 cm.sup.-3 and the sum of dislocation etch pit density and small conical etch pit density of the surface (111)B which has been subjected to etching for 3 to 5 minutes with RC etchant at a temperature of 65.degree. C..about.75.degree. C. after removing the mechanically damaged layer on the surface does not exceed 1.times.10.sup.5 cm.sup.-2, and a method of manufacturing the crystals.

Method of manufacturing gallium phosphide single crystals with low

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Hyogo, Japan

Kazuhisa Matsumoto