Analysis of point defects in AlN epilayers by cathodoluminescence spectroscopy

We present a systematic cathodoluminescence study yielding a clear correlation between the different growth conditions and the appearance and strength of the characteristic luminescence fingerprints of the individual point defects in AlN. In particular, the incorporation of oxygen and the formation of oxygen-related and probably silicon-related D X centers as well as the native Al and N vacancies are still a problem. The thermal activation of the deep defect centers is investigated by temperature dependent cathodoluminescence spectroscopy.