Tunable Drift-Diffusion Synergy in Suspended Te Nanowires for Multistate Photodetection.

Abstract

Tuning the interplay between photoconductive (drift-driven) transport and photothermoelectric (diffusion-driven) transport in a single device remains crucial for next-generation optoelectronics and in-sensor computing. Here, we present a suspended tellurium nanowire (Te NW) photodetector that concurrently harnesses and actively balances these two transports using asymmetric (local) or symmetric (flood) illumination in tandem with a bias voltage. This enables on-demand transitions from diffusion-dominated to drift-dominated photoresponses at room temperature, a feat not realized in prior Te-based detectors. Under zero bias with local illumination, robust photothermoelectric diffusion yields positive or negative photocurrents, with a responsivity <i>R</i>_i of 124.28 A/W and specific detectivity (<i>D</i>*) of 7.80 × 10¹¹ Jones. Conversely, flood illumination under finite bias triggers photoconductive drift, with a peak responsivity <i>R</i>_i of 65.03-68.79 A/W and <i>D</i>* of 7.99 × 10¹⁰-8.47 × 10¹⁰ Jones. By programming the illumination and bias conditions, we realize positive, negative, or zero photocurrent states, forming a three-mode response platform. Remarkably, the device exhibits a sub-100 μs response time and retains stable detection under ambient conditions, illustrating its viability for real-world applications. This work establishes a versatile blueprint for broadband, multistate photodetection toward in-sensor computing tasks.