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Title: Origin of additional spectral features in modulated reflectance spectra of 2-dimensional semiconductor systems

High resolution photoreflectance (PR) spectroscopy study on a single GaAs/AlGaAs quantum well representing a two-dimensional (2D) system, shows additional distinct spectral features on the high energy side of the first confined heavy-hole and light-hole exciton transitions. The PR experiments involved a special dual detection technique which significantly improved the measurement sensitivity. Photoluminescence excitation spectroscopy data on the sample showed broadened step-like features around these energies. A detailed lineshape analysis, including first principles simulations, was performed to understand the origins of these additional PR spectral features. They are shown to arise primarily from inhomogeneously broadened first excited state transition of the excitons, rather than from a change in the joint density of states at the exciton continuum edge. The analysis suggests that such features are more likely in the case of 2D excitons as compared to 3D excitons in bulk material. Apart from its significance for post-growth characterization, identification of these additional PR features enables direct estimation of the exciton binding energy.
Authors:
;  [1]
  1. Department of Condensed Matter Physics and Material Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)
Publication Date:
OSTI Identifier:
22271166
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 12; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ALUMINIUM ARSENIDES; BINDING ENERGY; COMPARATIVE EVALUATIONS; EMISSION SPECTROSCOPY; ENERGY-LEVEL DENSITY; EXCITATION; EXCITED STATES; EXCITONS; GALLIUM ARSENIDES; HOLES; PHOTOLUMINESCENCE; QUANTUM WELLS; SEMICONDUCTOR MATERIALS; SPECTRAL REFLECTANCE; TWO-DIMENSIONAL CALCULATIONS