An XPS study of the oxidation of AlAs thin films grown by MBE

AlAs films grown by MBE and cleaned with light Ar+ sputtering have been oxidized with various exposures of O2 and H2O at room temperature and studied with XPS. Analysis of XPS at various exposures of the disordered AlAs surfaces showed the formation of an Al2O3 layer with the loss of As leaving what has tentatively been assigned as As0 within and on the Al2O3 layer. Oxidation of the As was not observed until after heavy O2 exposures (∠1011L). The rate of Al2O3 formation on the disordered AlAs film was found to be approximately comparable to that on metallic Al. Oxide formation by H2O exposure was found to be about four times faster than with O2.