Polarity‐Switchable and Self‐Driven Photo‐Response Based on Vertically Stacked Type‐III GeSe/SnS2 Heterojunction

Abstract 2D van der Waals (vdWs) heterostructure‐based multifunctional field effect transistor (FET) has brought about novel physical phenomena. Impressively, anti‐ambipolar characteristic is one of the basis logic functions being used in multi‐valued inverters, which is analogous to negative differential resistance (NDR)‐based transistor. Here, the tunable current‐transport and self‐driven optoelectrical properties of vertically stacked multilayer GeSe/SnS 2 heterostructure are reported. In particular, it allows to be switched from n‐type‐dominant behavior to anti‐ambipolar operation regime (a large peak‐to‐valley ratio (PVR) of 1.5 × 10 3 ) as a result of different band‐bending under various bias. Under light‐doping engineering, the inverted V‐shaped peak is distinctly shifted because of the higher carrier recombination probability of p‐GeSe component. Besides, for photovoltaic performances, the device exhibits an ultralow dark current of ≈30 fA, a maximum responsivity of 130 mA W −1 , and high I on / I off ratio of ≈10 5 under 532 nm because of the large band offset and the efficient carrier separation process. Meanwhile, the polarization sensitivities can reach 1.9 at 405 nm and 2.6 at 635 nm. It is found that the polarity‐switchable behavior and self‐driven photodetection performance in GeSe/SnS 2 vdWs FET can hopefully broaden and simplify the multifunctional integrated devices in the future.