Abstract
The direct measurement of the free-exciton binding energy in a GaAs-As single quantum well is presented as a function of the well width . In the 20-K photoluminescence excitation spectra, 1s and 2s states of both heavy- (HH) and light-hole (LH) coupled excitons were detected, and was obtained from the separation of the two states. The for both HH and LH coupled excitons have their maximum around =10 monolayers (ML), and of LH excitons is smaller than that of HH excitons for ≤14 ML. The trend of dependence of agrees well with the theoretical prediction, which accounts for the finiteness of the barrier of a low-dimensionally confined electron and hole. However, the drastic increase of in the vicinity of the maximum, with the maximum value approximately four times the bulk value, is believed to be a transition to the two-dimensional exciton by the confinement of a quantum well.
- Received 28 September 1992
DOI:https://doi.org/10.1103/PhysRevB.47.2042
©1993 American Physical Society