Abstract
We demonstrated a single microwire photodetector first made using a VO 2 microwire that exhibted high responsivity (R λ ) and external quantum efficiency (EQE) under varying light intensities. The VO 2 nanowires/microwires were grown and attached on the surface of the SiO 2 /Si(100) substrate. The SiO 2 layer can produce extremely low densities of long VO 2 microwires. An individual VO 2 microwire was bonded onto the ends using silver paste to fabricate a photodetector. The high-resolution transmission electron microscopy image indicates that the nanowires grew along the [100] axis as a single crystal. The critical parameters, such as R λ , EQE, and detectivity, are extremely high, 7069 A W -1 , 2.4 × 10 10 %, and 1.5 × 10 14 Jones, respectively, under a bias of 4 V and an illumination intensity of 1 μW cm -2 . The asymmetry in the I-V curves results from the unequal barrier heights at the two contacts. The photodetector has a linear I-V curve with a low dark current while a nonlinear curves was observed under varing light intensities. The highly efficient hole-trapping effect contributed to the high responsivity and external quantum efficiency in the metal-oxide nanomaterial photodetector. The responsivity of VO 2 photodetector is 6 and 4 orders higher than that of graphene (or MoS 2 ) and GaS, respectively. The findings demonstrate that VO 2 nanowire/microwire is highly suitable for realizing a high-performance photodetector on a SiO 2 /Si substrate. © 2014 American Chemical Society.