Abstract: Room-temperature ultrathin ferroelectrics are crucial to building high density non-volatile memory. In the past decades, conventional ferroelectric thin films, for example complex ferroelectric perovskite oxide, has attracted enormous attention. However, limited by the possible critical size effect or the ferroelectricity vanishing below a critical film thickness, developing modern nanoelectronic devices based on conventional ferroelectric thin film poses a great challenge. Two-dimensional (2D) van der Waals (vdW) material, which has a naturally stable layered structure, saturated surface chemistry, and weak inter-layer interaction, offers an excellent platform for realizing ferroelectricity at atomic scale in the 2D limit. The layered 2D ferroelectrics provide the opportunity and possibility for further miniaturization of nanoelectronics as well as developing novel flexible electronics. In this paper, the research background of conventional ferroelectrics was reviewed, recent research progresses of 2D ferroelectricity and related device applications in vdW materials were highlighted, and a brief outlook on future application of 2D ferroelectrics was presented.

Key words: two-dimensional material, room-temperature ferroelectricity, ferroelectrics, ferroelectric device, non-volatile memory