Gas sensing properties and role of oxygen vacancies in Indium Oxide nanowires

We report on the effect of oxygen vacancies on defect related emission and the electronic properties of In$_{2}$O$_{3}$ nanowires, synthesized by vapor phase transport. The as-grown nanowires connected in an FET type of configuration shows n-type conductivity, which is ascribed to the presence of oxygen vacancies in the nanowire. The resistivity, transconductance, field effect mobility and carrier concentration of the In$_{2}$O$_{3}$ nanowires were determined to be 1.82 x10$^{-2 }\Omega $cm, 11.2 nS, 119 cm$^{2}$V$^{-1}$s$^{-1}$ and 4.89 x 10$^{17}$cm$^{-3}$ respectively. The presence of oxygen vacancies was also confirmed by photoluminescence measurements, which show a strong U.V emission peak at 3.18 eV and defect peaks in the visible region at 2.85 eV, 2.66 eV and 2.5 eV. We present a technique of post-growth annealing in O$_{2}$ environment and passivation with (NH$_{4})_{2}$S to reduce the defect induced emission. A single In$_{2}$O$_{3}$ nanowire with ohmic contacts was found to be sensitive to gas molecules adsorbed on its surface.