Anti-ambipolar phototransistors based on 1D GaAsSb/2D MoS₂ heterojunctions

The incapability of modulating the photoresponse of the assembled heterostructure devices has remained a challenge for the development of optoelectronics with multi-functionality. In this presentation, a gate-tunable and anti-ambipolar phototransistor is reported based on 1D GaAsSb nanowire/2D MoS₂ nanoflake mixed-dimensional van der Waals (vdW) heterojunctions. The resulting heterojunction shows apparently asymmetric control over the anti-ambipolar transfer characteristics, possessing potential to implement electronic functions in logic circuits. Meanwhile, such 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 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 explored in the heterojunction as well. Finally, a visible image sensor based on this hybrid device is demonstrated with excellent imaging capability, suggesting the promising application prospect in future optoelectronic systems.