High-responsivity Two-dimensional p-PbI <sub/>2</sub> /n-WS <sub/>2</sub> Vertical Heterostructure Photodetectors Enhanced by Photogating Effect

摘要： Two-dimensional (2D) vertical p-n heterostructure photodetectors are significant building blocks in nanoscale integrated optoelectronics. However, the unsatisfactory photosensing performance combined with complicated fabrication process still remains a challenge. In this work, the fabrication of high performance vertical photodetectors based on vapor grown p-PbI2/n-WS2 heterostructures is reported, in which the WS2 serves as the photogate to modulate the channel current. Due to the photogating effect in the heterostructures, the recombination of photo-excited electron–hole pairs is effectively suppressed, leading to high photoresponsivity up to 5.57 × 102 A W-1, which represents the highest value among the ever reported vapor-grown vertical p-n heterostructures. Moreover, the photoresponsivity is highly tunable through the gate voltage bias, and can be further improved to 7.1 × 104 A W-1 by applying a negative gate voltage bias of -60 V. The excellent photosensing properties of the PbI2/WS2 heterostructures combined with the facile synthesis method suggest a great potential in developing high performance 2D optoelectronic devices.