Epitaxial growth of cubic Mg0.45Zn0.55O thin films on SrTiO3 (001) substrate with MgO buffer layer

Abstract Cubic Mg 0.45 Zn 0.55 O thin films with MgO buffer layer were epitaxially grown on SrTiO 3 substrate by radio frequency oxygen plasma assisted molecular beam epitaxy. X-ray diffraction measurements indicate high quality single crystal films of (200) orientation. The growth follows cubic-on-cubic alignment with epitaxial relationship of Mg 0.45 Zn 0.55 O (001)[100]//MgO (001)[100]//SrTiO 3 (001)[100]. Atomic force microscopy measurements reveal a smooth surface with the rms roughness of 0.36 nm in an area of 5×5 μm 2 . The band gap of the film is calculated to be 4.8 eV and in the solar blind range. Since the MgO buffer layer can suppress the sub-band-gap photoresponse from the SrTiO 3 substrate and does not absorb moisture like the bare MgO substrate, the Mg 0.45 Zn 0.55 O thin films with MgO buffer layer grown on SrTiO 3 substrate have promising applications in solar blind ultraviolet photodetectors.