Effect of Annealing on the Structural and Electrical Properties of GLAD Synthesized Vertical Aligned WO3 Nanowire

Abstract

This paper reports the fabrication of catalyst-free vertically aligned tungsten oxide (WO3) nanowire (NW) on Si substrate through glancing angle deposition technique incorporated in an electron beam evaporation system. The fabricated samples were annealed at 500 °C to study the effect on the structural properties. The average crystallite size increased from 67.51 to 76.24 nm after annealing. Also, the lattice strain and dislocation density were found to be decreased at 500 °C. A significant improvement on the surface morphology was observed for the annealed sample. Au electrode was used to fabricate the Au/WO3 NWs/Si structure and the electrical parameters were measured for both the as deposited and annealed sample. The annealed sample showed higher sensitivity toward the light by surface adsorption–desorption process as compared to as deposited WO3 NW. The responsivity, external quantum efficiency, and detectivity of the as deposited sample were 9.66 A/W, 3.33 × 103%, and 5.94 × 1012, respectively, which significantly enhanced to 50.95 A/W, 1.75 × 104%, and 1.05 × 1013 Jones, respectively, after annealing at a bias of 3 V. The rise time and fall time were calculated to be 1.33 and 0.94 s, respectively, at 3 V applied bias voltage, which is superior to the state of art of WO3-based photodetectors. Thus, the fabricated sample can be a potential candidate for photodetector application.