High-Temperature Ferroelectric Behavior of Al0.7Sc0.3N

Currently, there is a lack of nonvolatile memory (NVM) technology that can operate continuously at temperatures > 200 degrees C. While ferroelectric NVM has previously demonstrated long polarization retention and >10(13) read/write cycles at room temperature, the largest hurdle comes at higher temperatures for conventional perovskite ferroelectrics. Here, we demonstrate how AlScN can enable high-temperature (>200 degrees C) nonvolatile memory. The c-axis textured thin films were prepared via reactive radiofrequency magnetron sputtering onto a highly textured Pt (111) surface. Photolithographically defined Pt top electrodes completed the capacitor stack, which was tested in a high temperature vacuum probe station up to 400 degrees C. Polarization-electric field hysteresis loops between 23 and 400 degrees C reveal minimal changes in the remanent polarization values, while the coercive field decreased from 4.3 MV/cm to 2.6 MV/cm. Even at 400 degrees C, the polarization retention exhibited negligible loss for up to 1000 s, demonstrating promise for potential nonvolatile memory capable of high-temperature operation. Fatigue behavior also showed a moderate dependence on operating temperature, but the mechanisms of degradation require additional study.