Vibrational properties of a Li -- OH complex in ZnO*

Considerable interest has developed on the potential use of II-VI oxides as electronic and optical materials. In several cases alkali atoms have been suggested as dopants. We report on the theoretical and experimental investigation of infrared and vibrational properties of a Li-OH complex in ZnO. Earlier infrared experiments[1] revealed a broad OH-like band centered at 3577.3 cm$^{-1}$ (12K), with full width at half maximum ranging from 0.4 cm$^{-1}$ (12K) to 41.3 cm$^{-1}$ (300K) and a corresponding shift in peak position of - 29 cm$^{-1}$, suggesting a significant coupling of the OH stretch with other modes. We have performed similar experiments on the OD version of this defect and have theoretically investigated[2,3] the coupling of these stretch modes to other modes. The lack of a significant isotope dependence of the resulting parameters suggests that the defect couples to the host rather than the large-amplitude motion of the H or D itself. 1. L. E. Halliburton \textit{et al}., J. Appl. Phys. \textbf{96}, 7168 (2004). 2. B. N. J. Persson and R. Ryberg, Phys. Rev. B \textbf{32}, 3586 (1985). [3] M. Budde \textit{et al}., Phys. Rev. B \textbf{63}, 195203 (2001).