EPITAXIAL GE LAYERS ON SI VIA GEXSI1-XO2 REDUCTION - THE ROLES OF THEHYDROGEN PARTIAL-PRESSURE AND THE GE CONTENT

The epitaxial growth of an epi-Ge layer via GexSi1-xO2 reduction in hy drogen annealing is reported. GexSi1-x alloys with x = 0.52 and 0.82 w ere first grown epitaxially on Si substrates. They were then oxidized in a wet ambient and subsequently annealed in 5% or 100% H-2. The redu ction of Ge from its oxide state is observed in both samples with both ambients. However, an epitaxial Ge growth is only observed in the sam ple with x = 0.82 after the 5% H-2 annealing. The other three cases re sult in the formation of polycrystalline Ge. The roles of the hydrogen partial pressure and the Ge content are discussed and conditions unde r which this novel mode of solid-phase epitaxy can occur are explained .