Al(1-x)Sc(x)N-Based Ferroelectric Domain-Wall Memristors

Emerging wurzite-structured ferroelectrics can help satisfy the demand for high-performance ferroelectrics compatible with III-nitride and Si technology. One of their particularly appealing properties is related to the presence of conducting domain walls, which can be used as functional elements in the devices with electrically tunable resistance-memristors. Using a combination of piezoresponse force microscopy (PFM) and conductive atomic force microscopy (CAFM) techniques, the electrical conductivity of the head-to-head (H-H) domain walls in the Al0.85Sc0.15N thin films on the n-GaN substrate is directly demonstrated. Transmission electron microscopy (TEM) studies of the Al0.85Sc0.15N films reveal that the conducting nature of these domain walls is likely related to their inclination with respect to the polar axis, resulting in polarization discontinuity at the domain junctions. On the other hand, no increased conductivity has been detected for the tail-to-tail (T-T) domain walls reflecting a semiconducting nature of Al0.85Sc0.15N thin films. Modulation of the domain wall density by voltage pulses with varying amplitude or duration allows realization of multiple stable resistance states with the maximum ON/OFF ratio of over 1500. These findings pave the way for the next-generation of ferroelectric electronic devices compatible with III-nitride technology.