Structures and finite-temperature abundances of defects in In$_2$O$_3$-II from first-principles calculations

Abstract

We have studied intrinsic defect complexes in In$_2$O$_3$ using ab initio random structure searching (AIRSS). Our first-principles density-functional-theory calculations predict the thermodynamic stability of several novel defect structures. We combine the static lattice energy and harmonic vibrational energy with the often-neglected configurational entropy to construct the free energy, which is minimised to predict defect abundances at finite temperatures. We predict that some of our new defect structures - in particular our {In,2V$_\mathrm{O}$} and {2In,3V$_\mathrm{O}$} defects - can exist in significant abundances at finite temperatures, and their densities of electronic states indicate that they could play an important role in the unexpectedly high density of n-type charge carriers observed in In$_2$O$_3$.