A photomodulated reflectance study of InAs/GaAs self-assembled quantum dots

Photomodulated reflectance (PR) spectra have been measured for self-assembled InAs/GaAs quantum dot(QD) structures consisting of a pair of QD layers, with a GaAs spacer either 50 or 100 A thick. The PR clearly reveals five confined-state QD transitions, at both 80 and 300 K, as well as features from the two-dimensional confining and GaAs layers. The measuredQD transition energies correlate well with photoluminescencespectra at 13 K, using high laser excitation powers to incur level filling. Annealing one of the samples produces a strong blueshift in the QD transitions.

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