Improved crystalline quality of ZnO with inserting multi-buffer layers

To improve the crystalline quality of zinc oxide (ZnO) for further application in solar cells, multi-buffer layers (mBL) were inserted into ZnO thin films and fluorine-doped tin oxide (FTO) glass, by radio frequency (RF) magnetron sputtering. The characterization of ZnO thin films was carried out by X-ray diffraction (XRD), photoluminescence (PL), Hall-effect measurements, atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS), and DRUV-vis spectra (DRUV-vis). XRD and PL results show that the crystalline quality of ZnO has been successfully improved with inserted mBL, due to the increased crystallinity index of ZnO (002) and the increased near-band-edge (NBE) emission. The transmittance and bandgap of ZnO thin films has been slightly affected with inserted mBL.