PtTe2/WS2/Pyramidal-Si van der Waals Heterojunction with Semiconformal Interfaces toward High-Performance Photodetectors

Due to their facile device-integration capability and exceptional photodetection performance, two-dimensional (2D) material/Si van der Waals (vdW) heterostructure-based photodetectors have attracted significant attention in recent decades. However, achieving high responsivity, fast response speed, and a large linear dynamic range (LDR) simultaneously in a 2D material/Si vdW heterostructure has proven to be challenging. In this study, we successfully fabricated a PtTe2/WS2/pyramidal-Si vdW heterostructure with a semiconformal interface, which exhibits exceptional performance in terms of responsivity, response speed, and LDR. The fabrication process involves transferring a monolayer WS2 film onto a pyramidal-Si substrate, followed by sputtering a Pt film and subsequent tellurization. The presence of air gaps within the semiconformal interface plays a crucial role in enhancing the performance of the detector. The device shows a peak responsivity of 1.1 A/W and peak internal quantum efficiency of 211% at 903 nm. Additionally, the device demonstrates an ultralarge LDR of 72 dB and a fast response speed with rise and decay times of 53 and 64 μs, respectively, at 520 nm. These outstanding characteristics allow the device to function as a single-pixel imager capable of capturing grayscale images. This study provides a novel strategy for enhancing the performance of 2D/Si-based photodetectors.