Experimental study on the influence of annealing temperature on the piezoelectric property of ZnO bulk single crystal

By measuring the changes in the piezoelectric coefficient d33 of ZnO bulk single crystals before and after annealing, dependence of piezoelectric coefficient d33 on annealing temperature was obtained experimentally. After annealing, the piezoelectric coefficient d33 of the ZnO bulk single crystals with [0001] or [0001] orientation increases with increase of annealing temperature. Comparing the XPS and PL spectra before and after annealing, we found in this paper that the oxygen vacancy concentration on the Zn-terminated surface and O-terminated surface of ZnO bulk showed an opposite trend. This caused the redistribution of electrical domains within the entire bulk and achieved spontaneous polarization. As the annealing temperature increases, the gradual increase followed by stabilization in the oxygen vacancy concentration. Therefore, the relationship between the piezoelectric coefficient and annealing temperature satisfies the Boltzmann distribution.