Sliding ferroelectricity in van der Waals layered γ-InSe semiconductor

Two-dimensional (2D) van-der-Waals (vdW) layered ferroelectric semiconductors are highly desired for in-memory computing and ferroelectric photovoltaics or detectors. Beneficial from the weak interlayer vdW-force, controlling the structure by interlayer twist/translation or doping is an effective strategy to manipulate the fundamental properties of 2D-vdW semiconductors, which has contributed to the newly-emerging sliding ferroelectricity. Here, we report unconventional room-temperature ferroelectricity, both out-of-plane and in-plane, in vdW-layered gamma-InSe semiconductor triggered by yttrium-doping (InSe:Y). We determine an effective piezoelectric constant of similar to 7.5 pm/V for InSe:Y flakes with thickness of similar to 50 nm, about one order of magnitude larger than earlier reports. We directly visualize the enhanced sliding switchable polarization originating from the fantastic microstructure modifications including the stacking-faults elimination and a subtle rhombohedral distortion due to the intralayer compression and continuous interlayer pre-sliding. Our investigations provide new freedom degrees of structure manipulation for intrinsic properties in 2D-vdW-layered semiconductors to expand ferroelectric candidates for next-generation nanoelectronics. Exploring two-dimensional layered ferroelectric semiconductors is highly desired for ferroelectric-based devices. Here, the authors realize the room-temperature ferroelectricity in layered Y-doped gamma-InSe due to the microstructure modifications.

Automated summary

This paper reports the unconventional room-temperature ferroelectricity, both out-of-plane and in-plane, in the 2D-vdW γ-InSe semiconductor triggered by yttrium-doping (InSe:Y). The enhanced sliding switchable polarization is directly visualized, and the microstructure modifications, including stacking-faults elimination and a subtle rhombohedral distortion, are identified as the origin of this phenomenon. These findings provide new opportunities for manipulating the intrinsic properties of 2D-vdW layered semiconductors, expanding the potential ferroelectric candidates for future nanoelectronics.