Photoluminescence of AlGaN grown on bulk AlN substrates

The photoluminescence (PL) of AlGaN quantum wells with AlN barrier layers deposited on substrates fabricated of AlN single crystals is studied in the temperature range from 11to300K under pulsed band-to-band excitation of the well material. The abnormal temperature dependence of the PL peak position and differences in the character of the peak shift with increasing excitation power density observed at low and elevated temperatures are interpreted in terms of carrier/exciton localization and screening of the built-in electric field. The formation of these localized states with narrow energy distribution and high density is favorable for efficient light emission.