Purely in-plane ferroelectricity in monolayer SnS at room temperature

Abstract

2D van der Waals ferroelectric semiconductors have emerged as an attractive building block with immense potential to provide multifunctionality in nanoelectronics. Although several accomplishments have been reported in ferroelectric resistive switching for out-of-plane 2D ferroelectrics down to the monolayer, a purely in-plane ferroelectric has not been experimentally validated at the monolayer thickness. Herein, a micrometer-size monolayer SnS is grown on mica by physical vapor deposition, and in-plane ferroelectric switching is demonstrated with a two-terminal device at room temperature (RT). SnS has been commonly regarded to exhibit the odd-even effect, where the centrosymmetry breaks only in the odd-number layers to exhibit ferroelectricity. Remarkably, however, a robust RT ferroelectricity exists in SnS below a critical thickness of 15 layers with both an odd and even number of layers. The lack of the odd-even effect probably originates from the interaction with the mica substrate, suggesting the possibility of controlling the stacking sequence of multilayer SnS, going beyond the limit of ferroelectricity in the monolayer. This work will pave the way for nanoscale ferroelectric applications based on SnS as a new platform for in-plane ferroelectrics.

References in corpus (2)

• Out-of-plane Piezoelectricity and Ferroelectricity in Layered $\alpha$-In2Se3 Nano-flakes
• Tuning the ferro- to para-electric transition temperature and dipole orientation of group-IV monochalcogenide monolayers

Cited by in corpus (6)

• Recent Advances in Two-Dimensional Metal Monochalcogenides
• Possible persistence of multiferroic order down to bilayer limit of van der Waals material NiI${}_2$
• Experimental formation of monolayer group-IV monochalcogenides
• Metastable piezoelectric group IV monochalcogenide monolayers with a buckled honeycomb structure
• Micrometer-scale monolayer SnS growth by physical vapor deposition
• Noncollinear ferrielectricity and morphotropic phase boundary in GeS monolayer