Nanodomain Engineering for Programmable Ferroelectric Devices

We introduce a concept of programmable ferroelectric devices composed of two-dimensional (2D) and ferroelectric (FE) materials. It enables precise modulation of the in-plane conductivity of a 2D channel material through nanoengineering FE domains with out-of-plane polarization. The functionality of these new devices has been demonstrated using field-effect transistors (FETs) fabricated with monolayer molybdenum disulfide (MoS2) channels on the Pb(Zr,Ti)O3 substrates. Using piezoresponse force microscopy (PFM), we show that local switching of FE polarization by a conductive probe can be used to tune the conductivity of the MoS2 channel. Specifically, patterning of the nanoscale domains with downward polarization creates conductive paths in a resistive MoS2 channel so that the conductivity of an FET is determined by the number and length of the paths connecting source and drain electrodes. In addition to the device programmability, we demonstrate the device ON/OFF cyclic endurance by successive writing and erasing of conductive paths in a MoS2 channel. These findings may inspire the development of advanced energy-efficient programmable synaptic devices based on a combination of 2D and FE materials.