Bandgap narrowing and ethanol sensing properties of In-doped ZnO nanowires

Indium doping effects on the optical and electrical properties of ZnO nanowires are investigated. The abnormal Raman spectrum shows only a peak centred at 439 cm(-1) related to high E-2 mode, which is due to In doping. The acceptor binding energy is estimated to be 93 meV from the results of temperature-dependent photoluminescence spectra. The redshift of the bandgap edge is attributed to a merging of donor and conduction bands. The sensitivity of the sensors fabricated from In-doped ZnO nanowires is about 3 - 1 ppm ethanol, and increases nearly linearly up to 27 as the ethanol concentration is raised to 100 ppm. Our results indicate that the In-doped ZnO nanowires have potential applications in fabricating optoelectrical devices and gas sensors.