Patent GB-1023447-A (GB)
Title: Improvements in or relating to methods of heat-treating material
IPC: C30B15/30
Filed: 1962-11-20
Abstract: In the heating of a material by zone-melting, crystal pulling or sintering in the presence of the vapour of an element for doping the material or preventing decomposition thereof, the material and a decomposable compound of the element are placed in a sealed evacuated vessel, the compound is decomposed at least in part to form the element, the element is condensed to form a store, and the store is heated to form vapour during the heat treatment of the material. The material may be silicon; cadmium sulphide, selenide, or telluride; or the arsenide, antimonide, or phosphide of gallium, indium, or aluminium.  Silicon may be heated in the presence of phosphorus, arsenic, or antimony; cadmium sulphide, selenide, or telluride may be heated in the presence of cadmium produced from cadmium telluride; gallium arsenide may be heated in the presence of arsenic produced from gallium arsenide; and indium arsenide may be heated in the presence of arsenic produced from indium, gallium, or aluminium arsenide.  Aluminium and gallium which may be formed at the same time as the store have a gettering action for oxygen.  According to Fig. 3 (not shown), a molten zone 37 (heated by induction to 1238-1250 DEG C.) is passed through a rod 8 of gallium arsenide held between molybdenum holders 9 and 10 in an evacuated quartz vessel 2 sealed at ends 4 and 5, while a store of arsenic is heated by means of a resistance coil 36 to 610 DEG  C.  Before sealing, vessel 2 is evacuated while being heated to 650 DEG  C. (Fig. 1, not shown). Store 22 is produced from a charge 11 of gallium arsenide by heating to 1000 DEG  C. (Fig. 2, not shown).  In a modification (Figs. 4-6, not shown), charge 11 is contained in a connected tube which is separated from vessel 2 after formation of store 22.ALSO:In the heating of a material by zone-melting or crystal pulling in the presence of the vapour of an element for doping the material or preventing decomposition thereof, the material and a decomposable compound of the element are placed in a sealed evacuated vessel, the compound is decomposed at least in part to form the element, the element is condensed to form a store, and the store is heated to form vapour during the heat treatment of the material.  The material may be germanium or silicon; cadmium sulphide, selenide, or telluride; or the arsenide, antimonide, or phosphide of gallium, indium, or aluminium.  Germanium or silicon p  may be heated in the presence of phosphorus, arsenic, or antimony; cadmium sulphide, selenide, or telluride may be heated in the presence of cadmium produced from cadmium telluride; gallium arsenide may be heated in the presence of arsenic produced from gallium arsenide; and indium arsenide may be heated in the presence of arsenic produced from indium, gallium, or aluminium arsenide.  Aluminium and gallium which may be formed at the same time as the store have a gettering action for oxygen.  According to Fig. 3 (not shown), a molten zone 37 (heated by induction to 1238-1250  DEG C.) is passed through a rod 8 of gallium arsenide held between molybdenum holders 9 and 10 in an evacuated quartz vessel 2 sealed at ends 4 and 5, while a store 22 of arsenic is heated by means of a resistance coil 36 to 610  DEG C.  Before sealing, vessel 2 is evacuated while being heated to 650  DEG C. (Fig. 1, not shown). Store 22 is produced from a charge 11 of gallium arsenide by heating to 1000  DEG C. (Fig. 2, not shown).  In a modification, Figs. 4-6 (not shown), charge 11 is contained in a connected tube which is separated from vessel 2 after formation of store 22.