All van der Waals photodetector for ultralow dark current

Abstract

Modern optoelectronic technologies rely heavily on UV photodetectors, which transform UV light stimuli into electrical signals and are used to measure UV radiation levels useful in military communication, medicine and biology. In this work, we report a novel approach to mitigate dark current in Gr-GaS heterojunction by utilizing van der Waals contacted Au electrodes. The all van der Waals photodetector shows self-powered characteristics with rectification ratio of ~102, sub femto ampere dark currents and excellent photo response properties under illumination at 375nm. With detection ability of sub microwatt per square centimeter light of 375 nm at zero bias voltage, the device shows a self-powered responsivity of 16.21mA/W and specific detectivity of 2.12X1012 Jones with appreciable response times (rise/ fall) of 201.99ms/220.44ms with a linear dynamic range of 53.15dB. Such high-performance Gr-GaS-Au all van der Waals UV photodetector presented in this work is comparable to previously reported results, suggesting that it has great potential for UV-A band detection for weak light signals.