Dependence of cuprous oxide conductivity on metal doping: a hybrid density functional simulation

Multiple metallic elements were screened as doping agents to alternate conductivity in cuprous oxide (Cu2O). Energetic, charge transition levels and optical properties of Be, Mg, Ca, Sr, Zn, Cd, Hg, Al, Ga, and In substitutionally doped Cu2O systems were investigated based on first principles methods. Results of formation energy calculation under both Cu-rich and Cu-poor conditions indicate the easy incorporation of 2A (Be, Mg, Ca, and Sr) group impurities into the crystal lattice of Cu2O under both conditions. However, 3A (Al, Ga, and In) group impurities could be incorporated only under Cu-poor conditions. While, the incorporation of Zn, Cd, and Hg in Cu2O is energetically less favorable under both conditions. The calculated charge transition levels of these dopants revealed an n-type conductivity. The calculated work functions show n-type to p-type surface inversion behavior for some doped systems. This can explain the p-type conductivity of Mg-doped Cu2O found experimentally. Furthermore, the optical properties of each system are calculated to investigate the effect of the introduced impurity on Cu2O. This study can help identify potential dopants to use for solar cell fabrication.