Highly enhanced piezoelectric property of co-doped AlN

We propose a series of new compositions of AlN-based piezoelectric material based on the results of first-principles calculation. The composition is expressed by Al 1− x N, where the elements α and β are selected to maintain the charge neutrality of the host AlN. We found that the selection of Mg 2+ for α and Hf 4+ and Zr 4+ for β with y = 0.5 show good chemical stability with much better piezoelectric properties than pure AlN. Our results indicate broad compositional freedom for improving the piezoelectric properties of AlN by using the co-doping technique.