A PHOTOMODULATED REFLECTANCE STUDY OF INAS GAAS SELF-ASSEMBLED QUANTUM DOTS/

Photomodulated reflectance (PR) spectra have been measured for self-as sembled InAs/GaAs quantum dot (QD) structures consisting of a pair of QD layers, with a GaAs spacer either 50 or 100 Angstrom 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 la yers. The measured QD transition energies correlate well with photolum inescence spectra at 13 K, using high laser excitation powers to incur level filling. Annealing one of the samples produces a strong blueshi ft in the QD transitions. (C) 1998 American Institute of Physics. [S00 03-6951(98)02648-5].