OXYGEN ROUGHENING OF GE(001) SURFACES

The interaction of molecular oxygen with the Ge(001) surface is studied in terms of the immediate disordering effects which occur as oxygen impinges on the germanium surface. Using reflection high energy electron diffraction, the surface morphology of initially clean, smooth Ge(001) surfaces is monitored in situ, in real time, during exposure to molecular oxygen. Changes in the (001) surface dimer reconstruction, surface disordering, and ultimately, multi-level roughening of the surface are observed. The pressure and temperature dependence of the oxygen-induced surface disordering rate is presented. Details of the initial oxygen-germanium surface interaction are discussed in the context of changes to surface morphology and compared to previously proposed roughening and oxidation mechanisms which are based upon both mass-sensitive and chemically-sensitive surface analysis techniques.