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.