Soft x-ray spectroscopic investigation of Zn doped CuCl produced by pulsed dc magnetron sputtering

We report on a systematic investigation of the electronic properties of UV-light emitting Zn doped CuCl thin films implemented using near edge x-ray absorption fine structures (NEXAFS) and high-resolution x-ray photoemission spectroscopy. A clear shift of the valence band maximum towards higher binding energy by 0.2 ± 0.1 eV was observed in Zn doped CuCl as compared to undoped CuCl. This shift is in correlation with the increase in conductivity measured by the Hall effect measurements. A decrease in the optical band gap of CuCl film is also observed as a function of Zn doping. The profound changes in the full width at half maximum and the gradual disappearance of satellite features of Cu 2p core level photoemission as a function of Zn dopant are attributed to the reduced presence of the surface layer of Cu2+ species with d9 configuration in the doped films. These investigations help us to understand the doping mechanisms and underlying physics. The reduced presence of the Cu2+ related surface layer as a function of Zn doping is also verified using NEXAFS. (paper)