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Optical properties of near-surface exciton quantum wells*
Felipe Pérez-Rodríguez
Instituto de Física de la Universidad Autónoma de Puebla,
Apdo. Post. J-48, Puebla, Pue. 72570, México

An overview of investigations on near-surface semiconductor quantum wells, whose optical properties are  considerably affected by the interaction of the exciton with the sample surface will be given. Near-surface quantum wells with both weak and strong quantum confinement of excitons will be considered. In the regime of weak confinement, the effective width d of the quantum well is much larger than the exciton radius a0  and, therefore, the center-of-mass motion of the exciton is quantized. In the opposite case (strong confinement regime) the quantum-well thickness d is smaller than a0, hence the electron and hole are quantized separately in the growth direction and form a quasi-2D exciton due to the in-plane Coulomb interaction. When the exciton quantum well is very close to the sample surface, exciton dynamics is determined not only by characteristics of the quantum well, but also by factors such as the no-escape condition for the electron and hole at the sample boundary, the image potential, and surface roughness. Optical spectra (reflectivity, absorption, and  light-scattering cross section) for various systems of near-surface quantum wells will be presented. In addition, recent results for magneto-excitons in near-surface quantum wells will be discussed too.
*: This work is partially supported by CONACYT.

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