Polymorphism and Ferroelectricity in Indium(III) Selenide.

Two-dimensional indium(III) selenide (InSe) is characterized by rich polymorphism and offers the prospect of overcoming thickness-related depolarization effects in conventional ferroelectrics. α-InSe has attracted attention as a ferroelectric semiconductor that can retain ferroelectricity at the monolayer level; thus, it can be potentially deployed in high density memory switching modes that bypasses the traditional von Neumann architecture in device design. However, studies involving α-InSe are often hindered by difficulties in phase identification owing to mixing with β-InSe.

Atomic Imaging of Electrically Switchable Striped Domains in β'-In Se.

2D ferroelectricity in van-der-Waals-stacked materials such as indium selenide (In Se ) has attracted interests because the ferroelectricity is robust even in ultrathin layers, which is useful for the miniaturization of ferroelectric field effect transistors. To implement In Se in nanoscale ferroelectric devices, an understanding of the domain structure and switching dynamics in the 2D limit is essential. In this study, a biased scanning tunnelling microscopy (STM) tip is used to locally switch polarized domains in β'-In Se , and the reconfiguration of these domains are directly visualized using STM.