Light Polarization Sensitive Transistor Action in the van der Waals Ferroelectric 4H‐SnS 2

ABSTRACT Van der Waals (vdW) ferroelectric semiconductors provide a unique platform for exploring the interplay between spontaneous polarization, electronic transport, ion migration, and photocarrier generation at the nanoscale. Here, we establish a room‐temperature ferroelectric state in SnS 2 and its sensitivity to structural polytype by directly contrasting the centrosymmetric 2H‐phase with the polar 4H‐phase. Raman spectroscopy distinguishes the 2H and 4H polymorphs of SnS 2 through their characteristic phonon fingerprints. Piezoresponse force microscopy confirms room‐temperature ferroelectricity in the 4H phase, while the 2H phase exhibits no ferroelectric response. The built‐in polarization in a three‐terminal transistor device of the 4H‐SnS 2 is modulated significantly by electrostatic gating and on exposure to linear and circularly polarized light. This device reveals polarization‐controlled output characteristics with distinct gate‐voltage induced hysteretic response and thermally activated carrier transport, confirming p ‐type semiconducting behavior strongly coupled to ferroelectric polarization. The photoresponse likewise exhibits polarization‐assisted carrier separation, sublinear power‐law scaling, a nonmonotonic temperature response correlated with the characteristic Raman modes, ferroelectric hysteresis, and a pronounced dependence on the circular and linear polarization states of the incident laser beam. These results establish 4H‐SnS 2 as a promising material system for polarization‐driven electronic and optoelectronic technologies, including nonvolatile memory and photoferroelectric functionalities.