Multiple sliding ferroelectricity of rhombohedral-stacked InSe for reconfigurable photovoltaics and imaging applications

TL;DR

This paper demonstrates multiple sliding ferroelectric states in rhombohedral-stacked InSe, enabling tunable photovoltaic and imaging functionalities with high responsivity and fast response times.

Contribution

It reports the first observation of multiple sliding ferroelectric states in rhombohedral InSe and explores their application in tunable photovoltaics and imaging devices.

Findings

Multiple ferroelectric states observed in rhombohedral InSe.

Achieved a photovoltaic current density of ~15 mA/cm2.

Device exhibits high photoresponsivity (~255 A/W) and fast response.

Abstract

Through stacking engineering of two-dimensional (2D) materials, a switchable interface polarization can be generated through interlayer sliding, so called sliding ferroelectricity, which is advantageous over the traditional ferroelectricity due to ultra-thin thickness, high switching speed and low fatigue. However, 2D materials with intrinsic sliding ferroelectricity are still rare, with the exception of rhombohedral-stacked MoS2, which limits sliding ferroelectricity for practical applications such as high-speed storage, photovoltaic, and neuromorphic computing. Here, we reported the observation of sliding ferroelectricity with multiple states in undoped rhombohedral-stacked InSe ({\gamma}-InSe) via dual-frequency resonance tracking piezoresponse force microscopy, scanning Kelvin probe microscopy and conductive atomic force microscopy. The tunable bulk photovoltaic effect via the electric field is achieved in the graphene/{\gamma}-InSe/graphene tunneling device with a photovoltaic current density of ~15 mA/cm2, which is attributed to the multiple sliding steps in {\gamma}-InSe according to our theoretical calculations. The vdw tunneling device also features a high photo responsivity of ~255 A/W and a fast response time for real-time imaging. Our work not only enriches rhombohedral-stacked 2D materials for sliding ferroelectricity, but also sheds light on their potential for tunable photovoltaics and imaging applications.