Reliable nonvolatile memory black phosphorus ferroelectric field effect transistors with van der Waals buffer

Two dimensional materials based ferroelectric field effect transistors (2D-FeFETs) have attracted much attention due to the prospect of low power consumption information storage with alleviated short channel effect and fast processing speed. However, an often-observed and hard-to-control anti-hysteresis response of 2D-FeFETs, e.g., a hysteretic switching of the resistance states of the devices which is opposite to that of the actual polarization of the ferroelectric dielectric, represent a major issue in the industrial applications of such devices. Here, we demonstrate a van der Waals buffer layer technique that eliminates anti-hysteresis in 2D-FeFETs and restores their intrinsic hysteretic behavior. Our modified 2D-FeFETs showed outstanding performance including high room temperature carrier mobility, robust bi-stable states with fast response to gate, large on/off ratio at zero gate voltage, large and considerably more stable memory window, and a long retention time. During repeated gate operation, the memory window of the buffered device is ~7000 times more stable than the unbuffered device.