Excited states of the light- and heavy-hole free excitons observed in photoreflectance
- 15 January 1989
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 39 (2), 1442-1445
- https://doi.org/10.1103/physrevb.39.1442
Abstract
Excitonic transitions are observed at 10 K in a 225-Å As-GaAs multiple-quantum-well structure in photoreflectance (PR) spectra obtained using a novel double monochromator spectrometer. With an instrumental resolution of 0.06 meV, complete resolution of excitonic line shapes in PR is achieved. The and states of the lowest-lying heavy- and light-hole free excitons ( and ) are observed as well as the ground states of two forbidden excitons ( and ). The PR data are analyzed using an effective-mass theory based on a modulation of the built-in electric field as the dominant modulation mechanism. The measured values of the difference in energy between the and states of both the heavy-hole free exciton and light-hole free excitons agree with their calculated values. No evidence is observed in PR for contributions of the two-dimensional band-to-band continuum (quantum confined Franz-Keldysh effect). The identification of excitonic features is further supported by comparison with corresponding photoluminescence excitation measurements made on the same sample.
Keywords
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