Lower ferroelectric coercive field of ScGaN with equivalent remanent polarization as ScAlN

Abstract

The ferroelectricity of wurtzite, Sc x Ga1−x N (x = 0.35–0.44), was demonstrated in a metal–ferroelectric–metal capacitor. The remanent polarization (P r) obtained from positive-up negative-down measurements was high, exceeding 120 μC cm−2. The coercive field (E c) of Sc0.44Ga0.56N was approximately 3.6 MV cm−1 at 300 K, which decreased to 3 MV cm−1 at 473 K. We observed that regardless of the host material, the Sc concentration governed the E c value in Sc x Ga1−x N and Sc x Al1−x N, suggesting that the polarization switching started in the wurtzite unit cells containing Sc. Additionally, the E c of Sc x Ga1−x N was lower than that of Sc x Al1−x N when P r was equivalent.