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

AbstractFerroelectric 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.