The Effect of Substrate Material and Postannealing on the Photoluminescence and Piezo Properties of DC-Sputtered ZnO.

Zinc oxide (ZnO) thin films were deposited on various substrates by DC sputtering deposition. Thermal annealing was performed at up to 1,200°C in N₂ for 30 min. The effect was investigated using x-ray diffraction (XRD), photoluminescence (PL) spectra, scanning electron microscopy (SEM), and piezoresponse force microscopy (PFM). The influence on PL response depends both on substrate material and annealing temperature. The PFM images reveal that the ZnO films have inversion domains. While annealing improves the piezoresponse, the inversion domains still persist. The cross-sectional analysis of the inversion domains shows domain boundary widths of approximately 1.5 nm. [ABSTRACT FROM AUTHOR]