Photocurrent characteristics of individual ZnGa2O4 nanowires

ZnGa2O4 nanowires were grown via a low-pressure chemical vapor deposition method, and the electrical transport properties of these nanowires were investigated. It was found that the current across individual nanowires was several picoamperes at a bias of 30 V, and the current was insensitive to oxygen and temperature. These behaviors still maintained as the ZnGa2O4 nanowires were exposed to below-band-gap irradiation. In contrast, upon exposure to 254 nm ultraviolet light, the current across the nanowire increased a lot. With decreasing oxygen pressure or increasing temperature, the photocurrent increased evidently; this could be understood from the Langmuir model and the adsorption isobar, respectively. The present results demonstrate that surface-related processes especially oxygen chemisorption have significant effects on the photoelectric properties of nanostructures. The optically driven oxygen and temperature sensing as found in the ZnGa2O4 nanowires may find promising applications in functional devices. (C) 2007 American Institute of Physics.