A monocrystalline germanium film is grown on a sapphire substrate with a (1102) orientation. The substrate is first pretreated to restructure the (1102) surface plane. Typically, restructuring is accomplished by either an anneal at high temperature or ion bombardment. A monocrystalline germanium layer is grown on the pretreated surface by a vapor deposition process such as molecular beam epitaxy or chemical vapor deposition.

A corrosion resistant structure having an outer ceramic layer of alumina stabilized zirconia resistant to oxidation at high temperatures, over a base alloy selected from the group consisting of CoCrAlY and NiCrAlY and applied to the base alloy by physical vapor deposition process, such as reactive magnetron sputtering wherein the outer ceramic layer has a thickness of from about 0.5 .mu.m to about 200 .mu.m.