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 In 2 Se 3 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 In 2 Se 3 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-In 2 Se 3 film by chemical vapour deposition including distinct centimetre-scale 2D β′-In 2 Se 3 film by an InSe precursor. We also demonstrate that as-grown 2D β′-In 2 Se 3 films on mica substrates can be delaminated or transferred onto flexible or uneven substrates, yielding α-In 2 Se 3 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 In 2 Se 3 , enabling 2D memory transistors with high electron mobility, and polarizable β′–α In 2 Se 3 heterophase junctions with improved non-volatile memory performance. A chemical-vapour-deposition-based approach enables the phase-controllable synthesis of large-scale two-dimensional β-, β′- and α-In 2 Se 3 films.