A Novel PbS/n-IGZO Thin-Film Nano-Photodetector with High Responsivity and High Photo-to-Dark Current Ratio

A novel back gate phototransistor detector was developed. In this detector, Indium-Gallium-Zinc Oxide (IGZO) as the active layer was capped with PbS (Lead sulfide) thin film. It could be used as photodetector in the visible spectrum. An interdigital comb structure with high width-to-length ratio as source and drain electrodes was adopted to increase the device responsivity. It is useful to reduce the cost using PVD (Physical Vapor Deposition) for PbS film preparation by simplifing the fabrication process. The developed device exhibits mobility $(\mu)$ as high as 8.69 cm 2 V −1 s −1 and the responsivity up to $\mathbf{2.68}\times \mathbf{10}^{\mathbf{4}}\mathbf{A}/\mathbf{W}$, in addition with relative high photo to dark current ratio of 10 7 , low off-state current $\mathbf{1.0}\times \mathbf{10}^{-\mathbf{14}}\mathbf{A}$, high on/off current $(\pmb{I}_{on}/\pmb{I}_{off})$ ratio of 10 8 and better stability.