Figure 4
O 1 s XPS spectra and PL spectra of the ZnO thin films. (a) O 1 s XPS spectra of the ZnO thin films. Dots are the experimental data and lines are the fitting results. (b) The PL spectra of the ZnO thin films before and after depositing a 50-nm Al2O3 cap layer. The inset of (b) is the magnified area of the PL spectra from 450 to 600 nm.