Photoelectric Characteristics of Isotype Heterostructure p-WSe₂/p-Si Photodetector with Improved Photoresponsivity and Detectivity

A heterojunction photodetector was fabricated for the first time via chemical vapor deposition by combining a p-type WSe₂ monolayered triangular flake with a p-type Si substrate. Under illumination, the p-p isotype heterojunction exhibited a broad photoresponse range of 400-1550 nm under LED and laser light. The introduction of monotriangular and atomic thick p-WSe₂ flakes onto p-type Si greatly increased the photodetection capability with a long carrier lifetime and robust light absorption. The best performance of this device exhibited a minimized dark current of 5 nA, a record high photocurrent-to-dark-current ratio of ∼28111.88, an ultrahigh detectivity of 2.075 × 10¹⁵ jones, a high external quantum efficiency (EQE) of 133132%, and a high responsivity of 568.6 A/W under light illumination of 532 nm with 9.17 mW/cm² intensity. These engrossing results indicate that this p-WSe₂/p-Si heterojunction device has considerable potential for applications in next-generation photodetectors.