First Principles Calculations of the Electronic Properties of Bulk Cu2O, Clean and Doped with Ag, Ni, and Zn.

Abstract

Abstract Using first principles total energy calculations we have studied the electronic properties of bulk Cu2O, clean and doped with Ag, Ni and Zn. The calculated ground state structure of clean Cu2O is cubic. Its lattice constant a=4.30 A, and bulk modulus B0=108 GPa are in excellent agreement with experimental values a=4.27 A, and B0=112 GPa. In its ground state, Cu2O is a semiconductor material with a small direct band gap at the Γ point. Our calculated value of ∼0.5 eV is smaller than the experimental value of ∼2.0 eV, reflecting the problems of local density functional theory calculating the excited states. Doping with Ag, results in a reduction of the band gap. This result is important, since it implies that the band gap of Cu2O can be engineered by varying the amount of Ag in the crystal. Doping with Ni gives rise to a p-type semiconductor with the impurity levels above the valence band maximum, while doping with Zn results in a n-type semiconductor, with impurity levels above the conduction band minimum.