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Temperature dependent photoreflectance (PR) and photoluminescence experiments of the InAs/GaAs quantum dot (QD) structures were performed. At 20 K, effective band-gap transitions due to the InAs QDs, wetting layers, and GaAs buffer and cap layers were identified. Transition energies of the ground state and four excited states with nearly equal interlevel spacings (75–80 meV) were observed. The linewidth of the ground-state transition decreased as the temperature increased from 20 K to 100 K while the linewidth became broader at temperatures above 100 K. Energy features of the PR spectra originating from QDs and relating to the in-plane parabolic potentials were discussed. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Anisotropic property of type-II GaAs/GaAsSb heterostructures was studied by photoluminescence (PL) and photoconductivity (PC). It was found that the PL and PC spectra exhibit a strong in-plane polarization with respect to 〈011〉 axis with polarization degrees up to 40%. We showed that the polarization does not depend on the excitation intensity as well as temperature, which excludes any extrinsic mechanisms related to the in-plane anisotropy. The observed polarized optical properties of GaAsSb/GaAs multiple quantum wells was attributed to the intrinsic property of the orientation of chemical bonds at heterointerfaces. [ABSTRACT FROM AUTHOR]