Asymmetric Electrode-Driven Self-Powered Photodetector Using Cu_2-xS Film

Self-powered photodetectors through asymmetric contact modulation are a simple and efficient approach that has gained a lot of attention because they form an energy gradient in the band gap of the semiconductor. This energy gradient develops the self-assembly of the built-in electric field to separate the electron–hole pairs without any external bias, which facilitates long-term functioning of the device. Copper sulfide (Cu2-xS) is a promising p-type semiconductor for visible-near-infrared photodetectors due to its tunable band gap and electrical properties. In this work, a Cu2-xS-based metal–semiconductor–metal (MSM) photodetector with asymmetric electrodes (Au/Cu2-xS/Ag) is fabricated, and its photodetector properties are measured under visible and near-infrared (NIR) light illuminations. The fabricated Au/Cu2-xS/Ag structured device shows responsivity of 5.66 × 10–3 A/W and 11.24 × 10–3 A/W under visible (λ = 530 nm) and NIR (λ = 980 nm) light illuminations, respectively, even at zero bias. Finally, the obtained results attest that the fabricated self-powered photodetector is highly suitable for modern self-powered optoelectronic applications.