Controllable Phase Transition of Two-Dimensional In₂Se₃ from Interfacial Oxide Layers: Implications for High-Power Electronic Devices

Ultrathin III–VI semiconductors have garnered significant attention as potential candidates for electronic applications. Indium selenide (In 2 Se 3 ) exhibits fascinating ferroelectric properties and phase-dependent bandgap (1.3–2.8 eV), making it promising for applications in micro- and nanoelectronics field. However, the challenges of synthesizing large-sized, uniformly structured In 2 Se 3 films with the desired phase and ensuring their stability remain significant. In this study, we demonstrate a method for preparing two-dimensional (2D) In 2 Se 3 films by an atomic displacement reaction of In 2 O 3 in a selenium (Se) atmosphere. The phase structure of In 2 Se 3 films could be controlled from the γ to β phase by adjusting the reaction temperature, and the as-grown In 2 Se 3 films show good crystallinity and uniformity. Furthermore, we establish that h -BN, acting as the dual-sided encapsulation layers, effectively segregates the In 2 Se 3 films from atmospheric oxygen. This prevents deselenization and oxidation reactions, leading to a marked improvement in the stability of the In 2 Se 3 films. The research results will lay the foundation for the application of In 2 Se 3 in high-power, highly integrated micronanodevices, spanning across various areas including storage arrays, field-effect transistors, sensors, optoelectronics, and photovoltaics.