Electromechanical coupling coefficient k15 of polycrystalline ZnO films with the c-axes lie in the substrate plane

The (112macr0) textured polycrystalline ZnO films with a high shear mode electromechanical coupling coefficient k
₁₅
are obtained by sputter deposition. An overmoded resonator, a layered structure of metal electrode film/(112macr0) textured ZnO piezoelectric film/metal electrode film/silica glass substrate was used to characterize k
₁₅
by a resonant spectrum method. The (112macr0) textured ZnO piezoelectric films with excellent crystallite c-axis alignment showed an electromechanical coupling coefficient k
₁₅
of 0.24. This value was 92% of k
₁₅
value in single-crystal (k
₁₅
= 0.26)