Geometric, electronic and optical properties of zinc/tin codoped In2O3 modulated by the bixbyite/corundum phase transition.

As transparent conducting oxides (TCOs), In₂O₃ in the high pressure phase attracts extensive research interests. Because physical properties are determined by the geometric structures, we investigate the electronic and optical properties of Zn/Sn codoped In₂O₃ materials (IZTO) being modulated by the bixbyite/corundum phase transition via Density Functional Theory calculations. For IZTO in high pressure phase, i.e. corundum phase, Sn/Zn dopant pair tends to form face-sharing ZnO₆ and SnO₆ octahedrons. The radius differences between Zn²⁺/Sn⁴⁺ dopants and In³⁺ host cations make Jahn-Teller effect occur and IZTO transform from bixbyite to corundum phase under a slight higher pressure than that of pure In₂O₃. Although Zn/Sn cosubstitution of In ions may increase the free carrier effective mass m^* near the band edge, when IZTO crystal transforms to corundum phase, the more dense packing structure results in stronger cation s-orbital overlaps than in bixbyite phase, which makes m^* recover to a smaller value. In addition, corundum IZTO has a larger indirect band gap and a high dopant solubility. So these investigations may open a new way to search for TCOs materials with low indium content. [ABSTRACT FROM AUTHOR]