Anti-ambipolar behavior and photovoltaic effect in p-MoTe2/n-InSe heterojunctions

Abstract

van der Waals (vdW) heterostructures by artificially stacking different two-dimensional (2D) materials are a promising platform to achieve diverse physical phenomena and device functions. In general, the gate voltage is utilized to modulate the carrier concentration and transport, thus realizing novel electronic and optoelectronic devices such as logic circuit and ternary inverters. Here, we present a novel out-of-plane heterostructure stacked by the layered p-type MoTe₂ and n-type InSe. An anti-ambipolar transfer character was found in the heterojunction with a large work window (>60 V) and a high peak-to-valley current ratio (>10³). The underlying transport mechanism of the anti-ambipolar behavior was investigated through the energy band structure, and we then proposed a basic design principle for constructing anti-ambipolar devices based on a 2D vdW heterostructure with type-II band alignment. In addition, under 405 nm laser irradiation, the heterojunction exhibits a high self-driven photodetection performance with a photoresponsivity of 15.4 mA W⁻¹ and a specific detectivity up to ∼3.02 × 10¹⁴ jones in the absence of external bias. This work not only demonstrates high-performance multifunctional optoelectronics based on InSe/MoTe₂ heterostructures, but also provides a new understanding of the anti-ambipolar band alignment and its applications in multivalued logic circuits and flexible devices.