Abstract
This paper presents a systematic study on the optical characteristics of ground-state electron–heavy-hole excitons in /InP quantum wells, specifically focusing on the resonance energy, spatial energy inhomogeneity, and optical-absorption strength. The exciton resonance energy can be predicted by conventional effective-mass equations. The low-temperature broadening of the photoluminescence spectrum was studied in relation to the composition of and the excitation power density. We show the composition of fluctuates not only statistically within the exciton volume but also macroscopically, which is the primary cause for the inhomogeneous broadening of the exciton resonance in /InP quantum wells. The exciton migration over macroscopically fluctuating and its preferential recombination in the lower-energy regions is discussed based on our calculation of the exciton lifetime. The integrated intensity of the optical-absorption spectrum of exciton resonance was found to increase as the well band gap increased. Our theoretical formula indicates that this band-gap dependence is quantitatively correlated with the two-dimensional-exciton radius. We show that both the exciton radius and the magnitudes of composition fluctuations primarily determine the exciton optical-absorption strength in /InP quantum wells.
- Received 2 January 1991
DOI:https://doi.org/10.1103/PhysRevB.44.1782
©1991 American Physical Society