Method of producing epitaxially semiconductor layers

A process of producing an epitaxially deposited semiconductor layer uniformly composed of a material selected from the group consisting of silicon and germanium onto a substrate composed of a material selected from the group consisting of sapphire and a Mg-Al spinel, comprising the sequential steps of:

• preparing a wafer of said substrate for expitaxial deposition by cutting, polishing along specific crystal planes and freeing said wafer of damaged layers;
• placing the prepared wafer in an enclosed chamber on an inductively heated support means, flushing said chamber with an inert gas and heating said wafer up to at least the decomposition temperature of a thermally decomposable gaseous compound selected from the group consisting of SiH.sub.4 and GeH.sub.4 ;
• passing a stream of a reaction gas composed of a mixture of an inert gas and said thermally decomposable gaseous compound in an inert gas, said inert gas being selected from the group consisting of hydrogen and helium, through said chamber while maintaining said temperature of said wafer for a period of time sufficient to relatively quickly deposit a continuous seed layer of said material onto at least one surface of said wafer;
• and
• substantially simultaneously maintaining said stream of said reaction gas about said wafer and maintaining said temperature of said wafer while adding only a gaseous hydrogen halide selected from the group consisting of hydrogen chloride and hydrogen bromide to said stream of reaction gas for a period of time sufficient to relatively slowly deposit a further layer of said material onto said seed layer.