Fast Response UV Photodetection Using TiO₂ Nanowire/Graphene Oxide Thin-Film Heterostructure

Abstract

A UV detector was fabricated based on vertical TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanowires (NWs) grown over spin-coated graphene oxide (GO) thin film (TF) using glancing angle deposition technique. A small dark current (0.0254 μA/cm <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> at 4 V) was observed for the Au/TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> NW/GO TF/Si device. Interface trap charges played a significant role in high photocurrent under 380 nm light illumination, which leads to high trap-assisted tunneling. The modified band bending at higher energy light illumination of 300 nm opposed the carrier to tunnel through the junction and forced to decrease the current. Variation in photocapacitance was obtained, which verified the presence of interface trap charges. A high responsivity of 48.3 mA/W and also photosensitivity and detectivity of 82.7 and 2.26 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> Jones, respectively, were measured under 380 nm (113.8 μW/cm <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) illumination. A high rise time (48 ms) and fall time (40 ms) due to efficient charge separation between the TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and the GO device are reported.