Trapped charge and contact barrier effects in room-temperature monolayer 2H-MoTe2 photodetectors

Abstract Monolayer 2H-MoTe 2 is a highly attractive material for near-infrared ultrathin photodetectors, though its reduced dimensionality introduces pronounced sensitivity to metal contacts and charge trapping processes. Here, we examine the device physics by correlating gate-dependent transport, effective trapped-charge density, and Schottky-barrier effects. The fabricated p-type device demonstrates distinct photoresponse across visible and near-infrared wavelengths (532, 633, and 785 nm). Under low-power of 785 nm illumination, the device reaches its highest measured responsivity of 112.73 mA W − 1 and a shot-noise-limited specific detectivity of 1.98 × 10⁹ Jones. Applying a negative gate bias increases p-type carrier accumulation and improves carrier extraction, giving a maximum EQE of 17.82% and an internal photocurrent gain of ~ 13.47 × 10 3 . Taken together, these findings are consistent with a hybrid operating regime in which Schottky-barrier-limited transport contributes to suppressing the dark current, while trap-assisted carrier dynamics support enhanced responsivity and gain under low-power illumination.