2D Multifunctional Phototransistor Based on MoTe2/Graphene/SnS0.25Se0.75 Heterostructure with High Photogain and Reconfigurable Polarized Detection

Abstract

2D van der Waals (vdWs) heterojunctions exhibit facile fabrication process and tunable optoelectronic properties. However, suppressing interfacial charge traps and multifunctional photoresponse remain significant challenges. Here, the study designs a 2D multifunctional phototransistor based on ambipolar MoTe₂/graphene (Gr)/p-type SnS_0.25Se_0.75 double vdWs vertical heterostructure via alloy engineering. The middle Gr interlayer is pivotal in reducing interfacial charge traps, facilitating vertical photocarrier transportation, and enhancing light absorption coefficient. Under photogating effect, the trapped electrons in SnS_0.25Se_0.75 promote the photogating effect, resulting in the maximum photogain of 8084 and specific detectivity (D^*) of 8.2 × 10¹² Jones. Under photoconductive effect, a high responsivity (R) of 36.9 A W⁻¹ and D^* of 7.17 × 10¹¹ Jones are achieved. Under photovoltaic effect, the devices exhibit a remarkable R of 501 mA W⁻¹, D^* of 1.4 × 10¹¹ Jones. Notably, a self-driven photocurrent polarized ratio of 8 under 635 nm is achieved because of the anisotropic nature of SnS_0.25Se_0.75 and the effective double built-in electric fields. By varying the gate voltage, the polarization ratio can be modulated from 1 to 2.5, enabling reconfigurable polarized-sensitive detection. Above all, the designed heterojunction with multifunctional and reconfigurable polarization detection.