EVIDENCE FOR QUANTUM-DOT-LIKE STATES IN GAINN GAN QUANTUM-WELLS/

Localization of excitons in potential wells due to fluctuations in the local In content in GaInN/GaN quantum wells is now widely believed to lead to quantum-dot-like states. This is even thought to be of major importance for the operation of GaInN-based laser diodes. Using photol uminescence excitation spectroscopy we show that there is indeed a str ong localization of excitons in such quantum wells at low temperature. On the other hand, a comparison of room temperature absorption spectr a with optical gain spectra indicates just a ''normal'' exciton-to-pla sma transition and no relevance of localization for laser operation. ( C) 1998 Elsevier Science B.V. All rights reserved.