Stability, Electronic and Optical Properties of In$_2$O$_3$(ZnO)$_n$ Alloys

(In$_2$O$_3$)-(ZnO) heterostructural alloy has recently become a promising transparent conducting oxides (TCO) because it possesses combined physical properties such as excellent optical transmission, high electrical conductivity, chemical and thermal stability, and good film smoothness. However, the origin of these superior properties is not well understood. In this work, using first-principles methods, we have investigated the structural stability, electronic, and optical properties of In$_2$O$_3$(ZnO)$_n$ $(n = 1 - 5)$. In$_2$O$_3 $(ZnO)$_n$ forms layered hexagonal or rhombohedral In$_2$O$_3$(ZnO)$_n$ superlattices, which are isostructural with LuFeO$_3$(ZnO)$_n$. The deformed In$_2$O$_3$ layer is highly strained and plays an important role in determining the stability of the system. The calculated band structures show that these alloys has a direct band gap at the $\Gamma$-point and typical features as other known n-type TCOs. The calculated small effective mass for these materials is consistent with the high electron mobility for these system. The optical properties of these alloys are calculated and compared with that of In$_2$O$_3$ and ZnO.