First-principles study of transparent p-type conductive SrCu2O2 and related compounds -: art. no. 075111

Using first-principles band structure methods we have systematically studied the electronic and optical properties of p-type transparent conductive oxides SrCu2O2 and related compounds A(II)Cu(2)O(2), where A = Mg, Ca, and Ba, as well as their host material Cu2O. We show that all these compounds have direct band gap at the zone center (Gamma) with SrCu2O2 having the largest band gap. The trend of band gap variation of A(II)Cu(2)O(2) as a function of A(II) is explained in terms of atomic energy levels and atomic sizes of the A(II) elements. Transparency of SrCu2O2 is explained by the calculated dipole transition matrix elements. The calculated effective masses for the conduction band states are found to be larger than those for the valence states for SrCu2O2, opposite to the trend in conventional semiconductors and n-type transparent conductive oxides. We predict that adding a small amount of Ca (similar to16%) into SrCu2O2 can increase the band gap and reduce the hole effective mass of SrCu2O2, therefore, increase the transparency and conductivity.