Gate-Tunable Photovoltaic Behavior and Polarization-Sensitive Near-Infrared Photodetector Based on GeS₂/MoTe₂ Heterostructure

Self-powered photodetectors, which operate without the need for an external power supply, play a pivotal role in addressing the growing demands for low power consumption, environmental sustainability, and device miniaturization. These next-generation photodetectors have garnered significant attention due to their exceptional attributes, including high photoresponsivity, low dark current, and rapid photoresponse. GeS2 and MoTe2 materials, owing to their unique structural characteristics and superior optoelectronic properties, have been extensively explored for self-powered photodetection applications. In this work, we present a gate-tunable photovoltaic behavior and polarization-sensitive near-infrared (NIR) photodetector based on GeS<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>/MoTe<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> heterojunction. Under 850 nm illumination with an incident power density of 63.42 mW/cm², the device exhibits a high responsivity of 1.09 A/W and a specific detectivity of 1.42 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> Jones at zero bias, along with a fast response time of 56 ms. By applying a gate voltage, the photovoltaic performance can be effectively modulated, with the responsivity enhanced to 8.3 A/W and the detectivity improved to 1.09 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> Jones under a gate bias of –8 V. Furthermore, due to the anisotropic optical properties of GeS<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>, the device demonstrates pronounced polarization sensitivity. Leveraging its outstanding NIR performance, the GeS<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>/MoTe<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> photodetector is integrated into a multiband antibiotic concentration detection system, enabling efficient, accurate, and eco-friendly monitoring of antibiotic levels.