INSITU OXIDATION OF A THIN-LAYER OF GE ON SI(001) - OBSERVATION OF GEO TO SIO2 TRANSITION

A thin layer of Ge grown on Si(001) surface is oxidized in situ and investigated using XPS, AES, RHEED, and MEIS. The samples used are, Ge layer formed by deposition at room temperature and SiGe mixed layer formed by deposition at 550-degrees-C. Oxidation at 250-degrees-C of the RT grown layer leads to the formation of GeO and on heating the surface to 360-degrees-C, oxygen bonds with Si forming SiO2, thereby reducing GeO to elemental Ge. In the epitaxially grown layer (grown at 550-degrees-C), after oxidation, SiO2 and a small amount of GeO are formed. Similar reaction takes place on this surface also, forming SiO2 as the final product on the surface. In the RT grown layer, after oxidation, MEIS shows evidence for the diffusion of Si through the Ge layer towards the surface.