Electronic and optical properties of Au-doped Cu₂O：A first principles investigation

The Cu₂O and Au-doped Cu₂O films are prepared on MgO (001) substrates by pulsed laser deposition. The X-ray photoelectron spectroscopy proves that the films are of Au-doped Cu₂O. The optical absorption edge decreases by 1.6% after Au doping. The electronic and optical properties of pure and Au-doped cuprite Cu₂O films are investigated by the first principles. The calculated results indicate that Cu₂O is a direct band-gap semiconductor. The scissors operation of 1.64 eV has been carried out. After correcting, the band gaps for pure and Au doped Cu₂O are about 2.17 eV and 2.02 eV, respectively, decreasing by 6.9%. All of the optical spectra are closely related to the dielectric function. The optical spectrum red shift corresponding to the decreasing of band gap, and the additional absorption are observed in the visible region for Au doped Cu₂O film. The experimental results are generally in agreement with the calculated results. These results indicate that Au doping could become one of the important factors influencing the photovoltaic activity of Cu₂O film.