Doping-dependent electrical characteristics of SnO2 nanowires.

Tin dioxide (SnO2) represents an importantmetal-oxide group that can be suitable for a range of applications through the incorporation of dopants. For example, the electrical conductivity of intrinsic SnO2 depends strongly on the surface properties, as molecular adsorption/desorption will affect the band modulation and space-charge layer, which makes SnO2 an important conductance-type gas-sensing material. On the other end of the doping spectrum, degenerately donor (such as Sb, Ta, and F) doped SnO2 films are important transparent conductive oxide (TCO) materials due to their large bandgap (3.6 eV) and high conductivity. SnO2-based TCO films are expected to be a low-cost alternative to indium tin oxide films in various optoelectronic devices, such as flat-panel displays, solar cells, and light-emitting diodes. Recent studies have also found that transition metal (such as Co and Ni) doped SnO2 acts as a diluted magnetic semiconductor and can exhibit Curie temperatures higher than room temperature. On the other hand, extending the doping processes from bulk SnO2 to nanostructures has been shown to be challenging due to both synthetic issues and ‘‘self-purification’’ mechanisms. In previous studies on SnO2 nanowires/nanobelts, the samples were not intentionally doped and the carriers typically originated from oxygen deficiencies. Intentional doping of SnO2 nanowires was reported recently by our group. Herein, we report systematic studies of the effect of Sb doping on SnO2 nanowires and detailed electrical characterization of the nanowire devices. Our results demonstrate that undoped SnO2 nanowires show Schottky contact to Ti/Au electrodes in air and are suitable for the detection of UV light. Lightly Sb-doped nanowires are promising as high-performance nanowire transistors, and degenerately Sb-doped SnO2