Titanium-doped indium oxide: A high-mobility transparent conductor

Abstract

We report on the effects of titanium doping $(0–7\mathrm{at.}\%)$ on the optical and electrical properties of ${\mathrm{In}}_2{\mathrm{O}}_3$ using combinatorial deposition and analysis techniques. Maximum mobilities are observed at Ti concentrations of $1.5–2.5\mathrm{at.}\%$ and are $>80{\mathrm{cm}}^2∕\mathrm{V}\mathrm{s}$ in sputtered films. The carrier concentration increased with titanium content to a high of $8.0\times {10}^{20}{\mathrm{cm}}^{-3}$ . Data show that one carrier is generated per added Ti between 1 and $3\mathrm{at.}\%$ . Conductivities up to $6260{\Omega }^{-1}{\mathrm{cm}}^{-1}$ were observed. These remained very high $>5000{\Omega }^{-1}{\mathrm{cm}}^{-1}$ across a wide compositional range. The optical transparency is high $(>85\%)$ in a wide spectral range from $400\mathrm{nm}$ to at least $1750\mathrm{nm}$ . The work function of titanium-doped indium oxide varies substantially over the studied compositional range.