Anomalous behaviour of the photoluminescence from GaN/AlGaN quantum wells

Temperature and excitation power dependencies of photoluminescence from GaN/AlGaN quantum well structures are studied. We show that depending on the well width, the increase of the excitation power results in the blue or red shift of the emission energy. Temperature affects the observed emission energy shifts in a way which is entirely different from that for unstrained GaN bulk. Surprisingly, the observed differences are larger for wider wells. These results can be understood assuming that not only potential fluctuations but also built-in electric field and strain effects must be taken into account. The role of the particular mechanisms is discussed on the basis of performed calculations. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)