Depletion-mode ZnO nanowire field-effect transistor

Single ZnO nanowire metal-oxide-semiconductor field-effect transistors (MOSFETs) were fabricated using nanowires grown by site selective molecular-beam epitaxy. When measured in the dark at 25degreesC, he depletion-mode transistors exhibit good saturation behavior, a threshold voltage of similar to-3 V, and a maximum transconductance of order 0.3 mS/mm. Under ultraviolet (366 nm) illumination, the drain-source current increase by approximately a factor of 5 and the maximum transconductance is similar to5 mS/mm. The channel mobility is estimated to be similar to3 cm(2)/V s, which is comparable to that reported for thin film ZnO enhancement mode MOSFETs, and the on/off ratio was similar to25 in the dark and similar to125 under UV illumination. (C) 2004 American Institute of Physics.