Access to the full text of the published version may require a subscription. We present eight-band k · p calculations of the electronic and polarization properties of columnar In z Ga 1−z As quantum dots ͑CQD͒ with high aspect ratio embedded in an In x Ga 1−x As/ GaAs quantum well. Our model accounts for the linear strain effects, linear piezoelectricity, and spin-orbit interaction. We calculate the relative intensities of transverse-magnetic ͑TM͒ and transverse-electric ͑TE͒ linear polarized light emitted from the edge of the semiconductor wafer as a function of the two main factors affecting the heavy hole-light hole valence band mixing and hence, the polarization dependent selection rules for the optical transitions, namely, ͑i͒ the composition contrast z / x between the dot material and the surrounding well and ͑ii͒ the dot aspect ratio. The numerical results show that the former is the main driving parameter for tuning the polarization properties. This is explained by analyzing the biaxial strain in the CQD, based on which it is possible to predict the TM to TE intensity ratio. The conclusions are supported by analytical considerations of the strain in the dots. Finally, we present the compositional and geometrical conditions to achieve polarization independent emission from InGaAs/GaAs CQDs.
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The simplifications of the Zn 3 P 2 -type crystal structure having tetragonal symmetry D 15 4h have been analysed. After description of the real unit cell the following simplifications are proposed: tetragonal symmetry (ideal and D 17 4h ), cubic symmetry and the correct molecular ratio (approximations O 9 h , T 7 h and O 4 h ) and finally the zincblende and antifluorite approximations. In the second part we present the results of energy band calculations for fully symmetric Zn 3 P 2 and for all the simplifications. The symmetry of bands is also determined for the full crystal structure and for the ideal approximation. In the calculations the nonlocal empirical pseudopotential method has been used.
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