Electronic structure of the interface of GaAs(1Â 0Â 0) with MgO overlayer grown by thermal evaporation of Mg in O2 under UHV

Thermal evaporation of Mg in oxygen atmosphere under UHV condition was conducted to fabricate ultrathin MgO film over GaAs(1 0 0) substrate at room temperature (TR). Synchrotron Radiation Photoemission Spectroscopy (SRPES) results show that very weak interaction and interdiffusion exist between the oxide overlayer and substrate indicating that the reaction between Mg and O2 is much more active than that between Mg with GaAs. The growth of MgO overlayer may be expected in such a mode that Mg reacts with O2 in gas phase or near surface to form MgO, followed by the deposition of MgO over GaAs(1 0 0).