Characterizations of Cubic ZnMgO Films Grown on Si(111) at Low Substrate Temperature

Cubic ZnMgO thin films in the (100) orientation were grown on Si (111) substrates by reactive electron beam evaporation at low substrate temperature. X-ray photoelectron spectroscopy (XPS) analyses show that Mg content as high as 75 at.% in the cubic ZnMgO film can be obtained. Secondary ion mass spectroscopy (SIMS) measurement indicates the evidence of Mg richness in the interface between the ZnMgO film and the Si substrate, and it is probably the primary reason to form the MgO-like cubic ZnMgO structures rather than the wurtzite one. The optical band gap of cubic ZnMgO is estimated to be 5.76 eV, which was measured by the transmission spectrum of the cubic ZnMgO film grown on the sapphire substrate under the same growth condition with that on Si (111). The band gap is of 2.39 eV blue shifted compared with that of ZnO (3.37 eV), which should render applications in the fabrication of ZnMgO-related heterostructures.