Abstract
Time-resolved photoluminescence studies have been performed on multiple quantum wells grown by molecular-beam epitaxy on a sapphire substrate. Radiative recombinations of excitons in both the wells and barriers exhibit average decay times of at with a significant spectral distribution of times. This distribution is interpreted in terms of localization of carriers by potential fluctuations due to alloy disorder and to well width and depth variations. The temperature dependence of the radiative lifetime of excitons in the wells is deduced from the measurement of both the photoluminescence decay time and intensity. We find that increases linearly with temperature dependence for From this result, we deduce the radiative lifetime of free excitons in the low-temperature limit (related to the oscillator strength) to be of 2.4 ps, i.e., half one order of magnitude smaller than for GaAs/Ga-Al-As quantum wells.
- Received 2 December 1997
DOI:https://doi.org/10.1103/PhysRevB.57.R9447
©1998 American Physical Society