Low Dark Current and High Responsivity UV Detector Based on TiO2 Nanowire/RGO Thin Film Heterostructure

A UV detector was fabricated using glancing angle deposition (GLAD)-synthesized TiO2 nanowires (NWs) over spin-coated reduced graphene oxide (RGO) thin films (TFs) on a Si substrate. The field-emission scanning electron microscopy (FE-SEM) images showed that TiO2 NWs were grown with a length of similar to 140 nm. The fabricated TiO2 NWs were amorphous in nature, as depicted by the selected area electron diffraction (SAED) pattern which was also verified by X-ray diffraction (XRD) analysis. On average, ninefold enhanced optical absorption was observed for the TiO2 NW/RGO TF/Si sample compared to the bare TiO2 NW/Si sample. A significantly low dark current of 2.9 nA (at + 1 V) was obtained after the incorporation of the RGO TF beneath the TiO2 NWs. The fabricated Au/TiO2 NW/RGO TF/Si device showed high responsivity and detectivity of 75.7 A/W and 6.86 x 10(13) Jones, respectively, under 380-nm light illumination having a power density of as low as 0.8 mu W/cm(2). A low noise-equivalent power (NEP) of 49 fW was also obtained from the resulting detector. The rise and fall times of the Au/TiO2 NW/RGO TF/Si detector were 0.8 and 1.09 s, respectively.