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

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The ferroelectricity of wurtzite, Sc x Ga 1− 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 μ C cm −2 . The coercive field ( E c ) of Sc 0.44 Ga 0.56 N 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 Ga 1− x N and Sc x Al 1− x N, suggesting that the polarization switching started in the wurtzite unit cells containing Sc. Additionally, the E c of Sc x Ga 1− x N was lower than that of Sc x Al 1− x N when P r was equivalent.