Defects, stress and abnormal shift of the (0 0 2) diffraction peak for Li-doped ZnO films

The effect of changes in Li content on the structural property of sol–gel Li-doped ZnO films was investigated in this study. The observed changes of the Li incorporation-induced strain along c-axis are closely related to the different ratios between the concentrations of Li interstitials (Lii) and Li substituting for Zn (LiZn) in the films. According to the observed results from X-ray diffraction (XRD) and photoluminescence measurements, we found that the domination of the dissociative mechanism in the Li-doped ZnO films led to transformation from LiZn to Lii, involving the formation of Zn vacancies (VZn). In addition, the interaction between these defects (that is, LiZn, Lii, VZn and oxygen vacancy) and the crystal structure may lead to the abnormal shift of the (0 0 2) diffraction peak position determined from XRD measurements.