Effects of Kr implanted O-polar ZnO thin films on structure and optical properties

Abstract Understanding of the structure and optical properties of films is important for their optoelectronic applications. In this paper, O-polar ZnO thin films were prepared by molecular beam epitaxy (MBE) on sapphire substrates, and Kr ions were doped into one of the films by ion implantation. Lattice structure and surface morphology of films were characterized by X-ray diffraction (XRD), Atomic force microscopy (AFM), respectively. The results show that compared with undoped O-polar ZnO film, the doped sample had granulated surface and enhanced absorption. Absorption Spectra, photoluminescence spectra (PL) and Spectroscopic Ellipsometry (SE) were used to characterize optical properties of films. The bandgap values obtained by absorption and SE method demonstrated that the bandgap decreases slightly as Kr ion implantation, and a new transition peak (3.56eV) appears from the SE result. This study provides information for controlling the band gap of ZnO materials by ion implantation and guidance for the application research of ZnO.