How does the multiple constituent affect the carrier generation and charge transport in multicomponent TCOs of In–Zn–Sn oxide

Abstract

The main purpose of this work is to make clear that in the newly synthesized multicomponent materials IZTO, namely, Sn/Zn cosubstituted In₂O₃, how can these cosubstituted dopants interact with each other and affect the electronic properties. We carry out a series of systematic Density Functional Theory calculations. Compared with ITO materials, the existence of Zn²⁺ in IZTO is important for the control of the electronic properties. Although there is large lattice distortion in the local structure around Zn²⁺ due to the Jahn–Teller effect, it releases distortions induced by other defects and thus reduces the formation energy of cosubstitution of the Zn/Sn impurity pair in In₂O₃. The V_O defect prefers to form in the ZnO₆ octahedron for the breaking of the Zn–O bond is easier than the Sn–O bond, which generates free electrons. In all IZTO configurations with and without defects, the bottom of conduction bands is comprised mainly of cation-s and O-p orbitals, which constructs a three dimensional network for charge transport. The bandstructure renormalization effect exerted by Zn atoms narrows the band gap. The existence of Zn atoms, on the one hand, weakens the spatial localization and orbital localization effects induced by defects and on the other hand strengthens the charge transport ability. These results indicate that the multicomponent semiconductor IZTO is an excellent candidate for the low indium content TCOs. Our work is useful to control the physical properties of IZTO experimentally, and is also helpful in understanding other multicomponent TCO materials.