Phase-controllable large-area two-dimensional In₂Se₃ and ferroelectric heterophase junction

Memory transistors based on two-dimensional (2D) ferroelectric semiconductors are intriguing for next-generation in-memory computing. To date, several 2D ferroelectric materials have been unveiled, among which 2D In₂Se₃ is the most promising, as all the paraelectric (β), ferroelectric (α) and antiferroelectric (β') phases are found in 2D quintuple layers. However, the large-scale synthesis of 2D In₂Se₃ films with the desired phase is still absent, and the stability for each phase remains obscure. Here we show the successful growth of centimetre-scale 2D β-In₂Se₃ film by chemical vapour deposition including distinct centimetre-scale 2D β'-In₂Se₃ film by an InSe precursor. We also demonstrate that as-grown 2D β'-In₂Se₃ films on mica substrates can be delaminated or transferred onto flexible or uneven substrates, yielding α-In₂Se₃ films through a complete phase transition. Thus, a full spectrum of paraelectric, ferroelectric and antiferroelectric 2D films can be readily obtained by means of the correlated polymorphism in 2D In₂Se₃, enabling 2D memory transistors with high electron mobility, and polarizable β'-α In₂Se₃ heterophase junctions with improved non-volatile memory performance.