Electronic structure of self-organized InAs/GaAs quantum dots bounded by {l_brace}136{r_brace} facets

assumed in previous electronic structure calculations for this system. In this paper, we consider theoretically the influence of the $136% shape on the electronic structure and optical properties of the quantum dots. We present a valence force-field calculation of the inhomogeneous strain and incorporate the results into an eight band k Wi p electronic structure calculation. The size dependence of the electronic structure is calculated and compared to experimental photoluminescence spectra. The effects of perturbations on the $136% shape are also considered. Calculations based on the $136% shape give good agreement with the observed level structure and optical polarization properties of self-organized InAs/GaAs quantum dots. The demonstration that defect-free quantum dot ~QD! structures may be fabricated directly by utilizing the coherent island Stranski Krastonov growth mode 1,2 has spurred tremendous experimental and theoretical research effort in recent years directed at understanding the electronic and optical properties of these structures. Many features of the electronic and optical properties of InAs/GaAs QD’s grown by this technique have been revealed in recent experiments. The quasi-atomic character of the joint density of states for optical transitions has been demonstrated. 3,5 Furthermore, photoluminescence spectra at high excitation intensity exhibit a well-resolved excited state structure, 6,7 which is consistent with the results of resonant photoluminescence and photoluminescence excitation measurements. 8‐10 Complementary experiments using capacitance methods reveal a similar general picture of the carrier density of states in these structures. 11,12 The high quality of the available samples coupled with the richness of the spectroscopic data thus far reported has motivated a number of calculations of the electronic structure of InAs/GaAs QD’s. While calculations have been performed to varying levels of approximation, all such studies necessarily contain assumptions regarding the QD shape. A number of experimental studies have been reported, which attempt to address the question of the shape of InAs/ GaAs self-organized QD’s. Atomic force microscope ~AFM! images of self-organized dots appear to show a lenslike morphology 13,14 which motivated electronic structure calculations assuming cone 16 or len shapes 17 for the dots. However, AFM is not capable of resolving the detailed shape of InAs/GaAs QD’s due to the tip-convolution effect. Likewise, transmission electron microscopy ~TEM! performed under the usual dynamical two-beam imaging conditions images the strain field within the structure and in the surrounding material and is consequently incapable of resolving the QD