Growth of wafer-scale two-dimensional ferroelectric CuCrS2 films
Two-dimensional ferroelectrics with high Curie temperature (Tc) enable stable ferroelectricity at the nanoscale, critical for miniaturized nonvolatile memory and in-memory computing. However, wafer-scale growth of 2D ferroelectric films with controlled thickness remains a bottleneck. This work reports a two-step vapour deposition method to grow wafer-scale 2D CuCrS2 ferroelectric films with uniform thickness from 2 to 10 nm. The films exhibit a non-centrosymmetric 3R stacking sequence, confirmed by second-harmonic generation (SHG) showing six-fold rotational symmetry. Ferroelectric polarization is demonstrated via hysteresis loops that strengthen with increasing temperature, attributed to ionized Cu movement above 200 K. The Tc exceeds room temperature, ensuring ferroelectric stability. Vertical memristor devices fabricated with 200 nm Au electrodes exhibit typical LRS-LRS memristor characteristics and robust hysteresis loops across multiple locations. The method is extended to CuCrSe2 films (7.8 nm thick) with Raman peaks at ~146 and 220 cm−1, confirming reproducibility. This work establishes a scalable route for integrating 2D ferroelectrics into next-generation electronic devices.