High-performance annealing-free wurtzite ferroelectric field-effect transistors with ultrathin oxide semiconductors for neuromorphic computing

Wurtzite-structured aluminum scandium nitride (AlScN) ferroelectric materials are potential candidates for non-volatile memory (NVM) applications because of their high remanent polarization (Pr > 100 μC·cm−2) and compatibility with back-end-of-line (BEOL) processes. However, achieving high-performance wurtzite ferroelectric field-effect transistors (FeFETs) remains a significant challenge because of their high interface trap density (Dit) and large threshold voltage (VTH) variation. Here we show the distinct polarization switching mechanisms of AlScN FeFETs based on an ultrathin indium gallium oxide (IGO) channel with three different structures. FeFETs with a metal–ferroelectric–metal–insulator–semiconductor (MFMIS) structure show high interface quality with low Dit and a stable VTH, achieving a large memory window (MW) of up to 20.6 V and a high endurance of 106. The stable 6-bit operation of our devices with 64 distinct states shows the feasibility of multilevel storage applications. Furthermore, we demonstrate the applicability of the FeFET in neuromorphic networks, with a high recognition accuracy of 93.02%. AlScN field-effect transistors for non-volatile memory are limited by high interface trap density and threshold voltage instability. Wang et al. demonstrate annealing-free AlScN ferroelectric transistors with low interface trap density and stable threshold voltage, enabling a large memory window and robust 6-bit operation.