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quantum dots; InAs/GaAs; magnetophotoluminescence
Abstract:
We report on photoluminescence of a series of vertically stacked multilayer quantum dot structures. Our analysis of the data taken at different excitation powers and in the magnetic field up to 24T yields a useful insight into the electronic structure of the InAs/GaAs quantum dot structures. The data are compared with results of model electronic-structure calculations for flat dots, including the effects of the strain field. The calculations suggest that the difference between the energies of the ground and first excited transitions is mainly determined by the lateral dimensions of the dots. A comparison of the experimental results with the theoretical ones reveals an increase of the dot dimensions (both height and diameter) and a decrease of the aspect ratio (height/diameter) with increasing number of the quantum dot layers. For seven-layer samples, the wavelength of 1.3 mu m has been achieved. The increase of the thickness of the spacing layers between adjacent dot layers leads to a decrease of the lateral dimensions of the dots, accompanied by an increase of the aspect ratio and of the energy separation between the ground and first excited transitions. (c) 2006 Elsevier B.V. All rights reserved.
