A switchable diode based on room-temperature two-dimensional\n ferroelectric {\\alpha}-In2Se3 thin layers

Abstract

Nanoscaled room-temperature ferroelectricity is ideal for developing advanced\nnon-volatile high-density memories. However, reaching the thin film limit in\nconventional ferroelectrics is a long-standing challenge due to the possible\ncritical thickness effect. Van der Waals materials, thanks to their stable\nlayered structure, saturate interfacial chemistry and weak interlayer\ncouplings, are promising for exploring ultra-thin two-dimensional (2D)\nferroelectrics and device applications. Here, we demonstrate a switchable\nroom-temperature ferroelectric diode built upon a 2D ferroelectric\n{\\alpha}-In2Se3 layer as thin as 5 nm in the form of graphene/{\\alpha}-In2Se3\nheterojunction. The intrinsic out-of-plane ferroelectricity of the\n{\\alpha}-In2Se3 thin layers is evidenced by the observation of reversible\nspontaneous electric polarization with a relative low coercive electric field\nof ~$2 X 10^5 V/cm$ and a typical ferroelectric domain size of around tens\n${\\mu}m^2$. Owing to the out-of-plane ferroelectricity of the {\\alpha}-In2Se3\nlayer, the Schottky barrier at the graphene/{\\alpha}-In2Se3 interface can be\neffectively tuned by switching the electric polarization with an applied\nvoltage, leading to a pronounced switchable double diode effect with an on/off\nratio of ~$10^4$. Our results offer a new way for developing novel\nnanoelectronic devices based on 2D ferroelectrics.\n