(Invited) Anti-Ambipolar Phototransistors Based on Mixed-Dimensional Heterojunctions

Abstract

The incapability of modulating the photoresponse of the assembled heterostructure devices has remained a challenge for developing optoelectronics with multi-functionality. In this presentation, we report a gate-tunable and anti-ambipolar phototransistor based on 1D GaAsSb nanowire/2D MoS2 nanoflake mixed-dimensional van der Waals (vdW) heterojunctions. The resulting heterojunction shows asymmetric control over the anti-ambipolar transfer characteristics, possessing the potential to implement electronic functions in logic circuits. Meanwhile, the anti-ambipolar device allows the synchronous adjustment of band slope and depletion regions by gating in both components, thereby giving rise to the gate-tunability of the photoresponse. Coupled with the synergistic effect of the materials in different dimensionality, the hybrid heterojunction can be readily modulated by the external gate to achieve a high-performance photodetector exhibiting a remarkable on/off current ratio of 4×104, fast response of 50 μs and high detectivity of 1.64×1011 Jones. Due to the formation of type-II band alignment and strong interfacial coupling, a prominent photovoltaic response is also explored in the heterojunction. Finally, a visible image sensor based on this hybrid device is demonstrated with excellent imaging capability, suggesting promising applications in future optoelectronic systems.