Patent GB-953110-A (GB)
Title: Improvements in or relating to methods of manufacturing semiconductor bodies
IPC: H01L21/00
Filed: 1960-08-26
Abstract: A wholly P-type body may be made by placing 10 grams of gallium in one limb of a two-limbed quartz tube and 3 grams of spectroscopically pure phosphorus in the other limb, exhausting and sealing the tube, and heating the first limb to 1170 DEG  C. and the second to 440 DEG C. in a double furnace for 3 hours.  The vaporized phosphorus dissolves in the gallium to give a solid solution of gallium phosphide in gallium on recrystallization which is effected by slowly cooling the first limb to 1000 DEG  C. and then cooling the whole system to room temperature. The phosphorus containing limb is removed, 260 mgs. of zinc added to the limb containing the solid solution and the evacuated and resealed tube reheated for 1/2 hour with the solution at 1170 DEG  C. and the cool end of the tube at 900 DEG  C.  After cooling as before the resulting zinc doped gallium phosphide is freed of excess gallium by heating in dilute hydrochloric acid and then washed and dried to give polycrystalline gallium phosphide.  Cadmium doped material is obtained by replacing the zinc by 300 mg. of cadmium in the above process and heating the colder part of the tube during doping to 800 DEG  C.  In otherwise essentially similar methods the first step is dispensed with and stoichiometric gallium phosphide used in the second step. Partial dissociation of the phosphide during doping may be avoided by including a sufficient quantity of free phosphorus in the tube to provide an equilibrium partial vapour pressure thereof at the temperature used. If an initially N-type gallium phosphide monocrystal is used in the above doping methods and the heating time controlled diffusion produces a P layer thereon.ALSO:A PN junction recombination radiation source is made from a body of gallium phosphide prepared in the manner described below. A wholly P-type body may be made by placing 10 grams of gallium in one limb of a two-limbed quartz tube and 3 grams of spectroscopically pure phosphorus in the other limb, exhausting and sealing the tube, and heating the first limb to 1170 DEG  C. and the second to 440 DEG  C. in a double furnace for 3 hours.  The vaporized phosphorus dissolves in the gallium to give a solid solution of gallium phosphide in gallium on recrystallization which is effected by slowly cooling the first limb to 1000 DEG  C. and then cooling the whole system to room temperature. The phosphorus containing limb is removed, 200 mgs. of zinc added to the limb containing the solid solution and the evacuated and resealed tube reheated for 1/2 hour with the solution at 1170 DEG  C. and the cool end of the tube at 900 DEG  C.  After cooling as before the resulting zinc doped gallium phosphide is freed of excess gallium by heating in dilute hydrochloric acid and then washed and dried to give polycrystalline gallium phosphide.  Cadmium doped material is obtained by replacing the zinc by 300 mg. of cadmium in the above process and heating the colder part of the tube during doping to 800 DEG  C.  In otherwise essentially similar methods the first step is dispensed with and stoichiometric gallium phosphide used in the second step.  Partial dissociation of the phosphide during doping may be avoided by including a sufficient quantity of free phosphorus in the tube to provide an equilibrium partial vapour pressure thereof at the temperature used. If an initially N-type gallium phosphide mono-crystal is used in the above doping methods and the heating time controlled diffusion produces a P layer thereon.  This is subsequently ground off and the resulting PN body provided with contacts to form a recombination radiation source. Specifications 719,873 and 757,672 are referred to.