Synthesis and Phase Transition of Large-Area Layered Ferroelectric Semiconductor α-In2Se3 via 2D Solid-Phase Crystallization

Abstract

Ferroelectric semiconductor α-In2Se3 has gained significant attention due to its favorable physical characteristics, including an appropriate bandgap (≈1.4 eV) for semiconductor devices, intercorrelated out-of-plane and in-plane polarization, and high Curie temperature (>200 °C). Combining its semiconducting and ferroelectric properties, α-In2Se3 holds promise for developing many innovative applications. However, the large-scale synthesis of uniform layered α-In2Se3 for practical use and a comprehensive understanding of its phase transition during synthesis are lacking. In this study, layered α-In2Se3 on amorphous SiO2 substrates at a cm2-scale is successfully synthesized and explored its phase transition during synthesis, by using a 2D solid-phase crystallization (2DSPC) method with a SiO2 encapsulation. The formation of highly crystalline 2D layered α-In2Se3 is observed through the real-time β-phase to α-phase transition at room temperature. The electrical (field-effect mobility µFE ≈ 1 cm2 V−1s−1), optical, and ferroelectric properties of the synthesized α-In2Se3 thin films are further investigated. This study contributes to the understanding and control of stoichiometry and phases of In2Se3 and provides an efficient approach for synthesizing large-area 2D layered α-In2Se3.