Metal-ferroelectric AlScN-semiconductor memory devices on SiC wafers

Abstract

This Letter presents oriented growth and switching of thin (∼30 nm) co-sputtered ferroelectric (FE) aluminum scandium nitride (AlScN) films directly on degenerately doped 4H silicon carbide (SiC) wafers. We fabricate and test metal ferroelectric semiconductor capacitors, comprising of Al/Al0.68Sc0.32N/4H-SiC. Our devices exhibit asymmetric coercive electric field values of −5.55/+12.05 MV cm−1 at 100 kHz for FE switching, accounting for the voltage divided by the depletion region of the semiconducting SiC substrate under positive voltages. Furthermore, the FE AlScN exhibits a remanent polarization of 110 ± 2.8 μC cm−2, measured via a voltage-pulsed positive-up negative-down measurement. We further investigate the reliability of the reported devices, revealing an endurance of ∼3700 cycles and a retention time of 9.5 × 105 s without any significant loss of polarization. Our findings demonstrate the bipolar switching of high-quality thin Al0.68Sc0.32N films on doped SiC substrates enabling monolithic integration of nonvolatile memory with SiC-based logic devices appropriate for high temperature operation as well as for high-power switching, memory, and sensing applications.