Tunable Ferroelectric Properties in Wurtzite (Al0.8Sc0.2)N via Crystal Anisotropy

The effect of pure mechanical strain on ferroelectricity was investigated for (001)-one-axis-oriented (Al0.8Sc0.2)N films deposited on (111)Pt-coated substrates with different thermal expansion coefficients. The mechanical lattice strains were successfully controlled by using substrates with different thermal expansion coefficients, though the composition of the films is the same. The changes in the remanent polarization (Pr) and coercive field (Ec) values of these films can be understood by the internal parameter u representing crystal anisotropy of a wurtzite structure. These results suggest that the ferroelectric properties of (Al1–xScx)N films can be tuned via crystal anisotropy.