Room temperature photo-induced phase transitions of VO2 nanodevices

We have successfully fabricated VO2 nanodevices using a photo-induced phase transition mechanism under an ultraviolet-light (lambda = 365 nm, I = 7 mu W cm(-2)). On the obtained VO2 nanowires, the photoinduced insulator-to-metal (IM) phase transition occurred from monoclinic (insulator or semiconductor) to tetragonal (metal) structures at room temperature. The photocurrent-to-dark current ratio of the nanodevice was 285 with ultra-fast response and recovery times of 1.3 and 4.5 ms, respectively, at a UV light intensity of 7 mu W cm(-2). As the UV light intensity increased to 2.33 mW cm(-2), a maximum photocurrent-to-dark current ratio of 719 was observed. A high-resolution transmission electron microscopy (HRTEM) image indicates that the nanowires grew along the [100] axis as a single crystal. The VO2 nanowires were then fabricated into field-effect transistor (FET) devices. High electron mobilities of 29 and 7.93 cm(2) V-1 S-1 were obtained with UV on (2.33 mW cm(-2)) and off, respectively. The electrical properties of the photo-induced IM phase transitions of the VO2 nanowires were investigated.