On the origin of carrier localization in Ga1-xInxNyAs1-y/GaAs quantum wells

We have investigated by temperature-dependent photoluminescence (PL) spectr oscopy as-grown GaInNAs, InGaAs, and GaAsN quantum wells (QWs) embedded in a GaAs matrix. The evolution of the PL peak position and of the PL linewidt h shows evidence of a strong carrier localization for the GaInNAs QWs only. The high delocalization temperature, in the 150 K range, indicates the pre sence of a high density of possibly deep-localizing potential wells. In add ition, a higher density of nonradiative recombination centers appears to re sult in stronger carrier localization. Transmission electron microscopy rev eals well defined, flat interfaces, in these comparatively high N-content ( y(N)similar to0.04-0.05) QWs. Our results thus demonstrate that the origin of localization in GaInNAs QWs is the concomitant presence of both In and N , which may result in strain and/or composition fluctuations. (C) 2001 Amer ican Institute of Physics.