Band Alignment Transition and Enhanced Performance in Vertical SnS<sub>2</sub>/MoS<sub>2</sub> van der Waals Photodetectors
Mingyu Shi, Yanhui Lv, Gang Wu, Jiung Cho, Mohamed Abid, Kuan‐Ming Hung, Cormac Ó Coileáin, Ching‐Ray Chang, Han‐Chun Wu
Abstract
The strong light–matter interaction and naturally passivated surfaces of van der Waals materials make heterojunctions of such materials ideal candidates for high-performance photodetectors. In this study, we fabricated SnS 2 /MoS 2 van der Waals heterojunctions and investigated their photoelectric properties. Using an applied gate voltage, we can effectively alter the band arrangement and achieve a transition in type II and type I junctions. It is found that the SnS 2 /MoS 2 van der Waals heterostructures are type II heterojunctions when the gate voltage is above −25 V. Below this gate voltage, the heterojunctions become type I. Photoelectric measurements under various wavelengths of incident light reveal enhanced sensitivity in the ultraviolet region and a broadband sensing range from 400 to 800 nm. Moreover, due to the transition from type II to type I band alignment, the measured photocurrent saturates at a specific gate voltage, and this value depends crucially on the bias voltage and light wavelength, providing a potential avenue for designing compact spectrometers.