Gate-Tunable Responsivity of PdSe2 Nanosheet-Based Bolometric Photodetectors for Mid-Infrared Light Detection

Photodetectors with tunable responsivity are highly desirable for intelligent light sensors. The charge carrier transport properties of two-dimensional materials can be easily tuned by electrostatic doping due to their ultrathin thickness, meeting the requirement of deep optical sensing. In this study, we present the tunable temperature coefficient of resistance (TCR) in palladium diselenide (PdSe2) nanosheet-based field effect transistors (FETs) via gate voltage modulation. By applying a gate voltage to a FET with SiO2 (285 nm) dielectric, the TCR can be finely tuned from -1 to -3% K-1. Substituting the thick SiO2 with a thin h-BN dielectric further allows for TCR tuning from -2 to -0.06% K-1. The tunable TCR is attributed to the control of activation energy by the gate voltage. In addition, we demonstrate that a PdSe2 nanosheet-based FET, fabricated on a PI substrate, can act as a bolometric photodetector whose responsivity to infrared illumination (9.3 mu m) can be electrically tuned. By modulation of the gate voltage, the responsivity can be adjusted from 21 to 245 mA/W. These findings suggest promising applications of PdSe2 nanosheet-based bolometers in next-generation intelligence infrared optoelectronic devices.