A Density Functional Theory Calculation Of The Oxygen Vibration Mode Frequencies In CdTe

The vibrational frequencies of oxygen impurity in CdTe have been calculated for a variety of oxygen environments using first-principle density functional theory. The local mode of an isolated oxygen atom substituting for Te is found to have a frequency of 331.86 cm$^{-1}$ as compared with the experimental value of 349.8 cm$^{-1}$. Two high frequency modes (at around 1104 cm$^{-1})$ have previously been identified with the vibrational modes of a complex consisting of a substitutional oxygen and a neighboring Cd vacancy. We found that the frequencies of such oxygen-complexes are far too low to explain the experimental results. In stead we found that the frequency of an oxygen molecule or dimmer located inside a Cd vacancy is in good agreement with experiment.