Self-Powered\nand Broadband Photodetector with High\nResponsivity and Fast Response Based on La-Doped PbSe Film Heterojunction

Abstract

PbSe is one of the most representative materials in lead\nchalcogenide\nsemiconductors, possessing a narrow bandgap and demonstrating excellent\nabsorption and photoresponse. However, undoped PbSe typically exhibits\nlow carrier concentrations, along with large dielectric constants\nand thermal expansion coefficients, imposing limitations on its application\nin a high-performance photodetector. Doping is an effective strategy\nto overcome the inherent defects and enhance the optical and electrical\nproperties. In this study, different compositions of Pb_1−<i>x</i>La_<i>x</i>Se samples were obtained\nthrough solid-phase method doping with the rare earth element La.\nThe doped Pb_0.7La_0.3Se showed superior optical\nand electrical properties and photoresponse. Additionally, based on\nthe approach of constructing heterojunctions with thin films and two-dimensional\n(2D) materials, a self-powered <i>p</i>−<i>n</i> heterojunction photodetector, Pb_0.7La_0.3Se/WSe₂, has been successfully fabricated. The device exhibited a\ncontinuous and stable light response from 405 to 1550 nm. Moreover,\nunder 0 V bias and 650 nm laser irradiation, the device achieved the\nresponsivity and specific detectivity of 22.85 A/W and 1.81 ×\n10¹² Jones, along with a rapid response/recovery time (162/135\nμs), demonstrating excellent photovoltaic effects and outstanding\nphotodetection performance. The construction of heterojunctions with\nfilm and 2D materials provides a novel approach to achieving high-performance\nphotodetectors. Simultaneously, the Pb_0.7La_0.3Se/WSe₂ detector shows enormous potential in the field\nof superior photodetectors with a high on/off ratio, low noise, broadband,\nrapid response, and miniaturization.