High-sensitive phototransistor based on vertical HfSe₂/MoS₂ heterostructure with broad-spectral response

Abstract

Van der Waals heterostructures based on two-dimensional (2D) semiconductor materials have attracted increasing attention due to their attractive properties. In this work, we demonstrate a high-sensitive back-gated phototransistor based on vertical HfSe2/MoS2 heterostructure with a broad-spectral response from near-ultraviolet to near-infrared and an efficient gate tunability for photoresponse. Under bias, the phototransistor exhibits high responsivity of up to 1.42 × 103 A/W, and ultrahigh specific detectivity of up to 1.39 × 1015 cmHz1/2W-1. Moreover, it can also operate under zero bias with remarkable responsivity of 10.2 A/W, relatively high specific detectivity of 1.43 × 1014 cmHz1/2W-1, ultralow dark current of 1.22 fA, and high on/off ratio of above 105. These results should be attributed to the fact that the vertical HfSe2/MoS2 heterostructure not only improves the broadband photoresponse of the phototransistor but also greatly enhances its sensitivity. Therefore, the heterostructure provides a promising candidate for next generation high performance phototransistors.