Oxygen removal from Si via reaction with adsorbed Ge

Silicon surface optimization prior to film growth is central to the fields of chemical vapor deposition and molecular beam epitaxy. We have examined a method for low-temperature in situ cleaning of the Si (100) surfaces utilizing a submonolayer coverage of germanium. Synchrotron excited x-ray photoemission data indicate that Ge atoms arriving at a Si (100) surface can break silicon-oxygen bonds, thereby producing new chemical species which sublimate at 625°C. In the absence of Ge, the observed silicon oxide species were stable at temperatures well in excess of 750°C. These results are used to investigate the mechanisms by which adsorbed Ge can be used to produce oxide-free Si (100) surfaces at 625°C.