Role of oxygen vacancies in visible emission and transport properties of indium oxide nanowires

We report on the effect of oxygen vacancies on the defect-related emission and the electronic properties of In2O3 nanowires. The nanowires were synthesized by vapor phase transport and had diameters ranging from 80–100 nm and lengths over 10–20 μm, with a growth direction of [0 0 1]. The as-grown nanowires connected in an FET type of configuration show n-type conductivity, which is ascribed to the presence of intrinsic defects like oxygen vacancies in the nanowire. The resistivity, transconductance, field effect mobility and carrier concentration of the In2O3 nanowires were determined to be 1.82 × 10−2 Ω cm, 11.2 nS, 119 cm2 V−1 s−1 and 4.89 × 1017 cm−3, respectively. The presence of oxygen vacancies was also confirmed by photoluminescence measurements, which show a strong UV 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 O2 environment and passivation with (NH4)2S to reduce the defect-induced emission.