Reversible Tuning Electrical Properties in Ferroelectric SnS with NH3 Adsorption and Desorption.

Two-dimensional (2D) ferroelectrics usually exhibit instability or a tendency toward degradation when exposed to the ambient atmosphere, and the mechanism behind this phenomenon remains unclear. To unravel this affection mechanism, we have undertaken an investigation utilizing NH₃ and two-dimensional ferroelectric SnS. Herein, the adsorption and desorption of NH₃ molecules can reversibly modulate the electrical properties of SnS, encompassing I-V curves and transfer curves. The response time for NH₃ adsorption is approximately 1.12 s, which is much quicker than that observed in other two-dimensional materials. KPFM characterizations indicate that air molecules' adsorption alters the surface potentials of SiO₂, SnS, metal electrodes, and contacts with minimal impact on the electrode contact surface potential. Upon the adsorption of NH₃ molecules or air molecules, the hole concentration within the device decreases. These findings elucidate the adsorption mechanism of NH₃ molecules on SnS, potentially fostering the advancement of rapid gas sensing applications utilizing two-dimensional ferroelectrics.