Self-powered near-infrared photodiode based on a MoSe2/MoS2 heterojunction

Abstract We report on the fabrication of a low-cost MoSe 2 /MoS 2 thin-film heterojunction on a p -type Si wafer with near-infrared (NIR) detection capabilities using low-temperature radio frequency (RF) sputtering with commercial targets. The device operates as a p – n photodiode at room temperature, with evidence of the creation of a p – n junction with rectification ratios of 10 3 and ideality factors of ~2.5. Under reverse-bias operation, the device has photogenerated currents of up to 65 nA, reaches a maximum photoresponsivity of 0.045 µA W −1 , and detectivities of up to 1.1 × 10 5 Jones. Moreover, the device can function as a self-powered photodetector with photogenerated currents of up to 16 nA with a photoresponsivity of 0.003 µA W −1 at 980 nm and detectivities in the order of 10 4 Jones. This work proves that facile, affordable, and compelling near-IR photodetectors can be fabricated using transition metal dichalcogenides integrated with Si technology and RF sputtering. Impact statement Scalable fabrication by radio frequency sputtering of a self-powered infrared photodiode, which means it can detect IR signals without an applied voltage. The device is formed from an n -type MoS 2 /MoSe 2 thin-film heterojunction directly deposited on a commercial p -type Si wafer. The electrical characteristics of the device indicate the formation of a p – n junction that creates a built-in potential. This built-in potential effectively separates the photogenerated charge carriers and permits the self-powered capacity of the device. Additionally, the results demonstrate a compelling performance that can compete with commercially available versions of infrared detectors, with the additional advantage of working without cooling systems and under low-power operation conditions.