This paper investigates the influence of indium segregation on the strain fields and electronic structures of self-assembled InAs/GaAs quantum dot structures with and without an In0.15Ga0.85As interlayer. We propose a new out-of-plane mismatch strain to interpret an experimental phenomenon. The new mismatch strain simulation successfully analyzes the strain fields and energy levels of InAs quantum dots (QDs). Numerical results reveal that indium segregation would improve the penetration behaviour of the z-axis strain component and the relaxation of the hydrostatic strain. The transition energy of samples A and B without In segregation are 0.991 and 1.028 eV, respectively. The energy difference of two samples agrees well with the previous experimental results. The transition energy of samples A and B may be consistent with presented experiment data at R = 0.84–0.85. In our calculations, indium segregation not only made the transition energy increase significantly as segregation efficiency increased, but also the confinement position of the electron and the heavy-hole shifted toward the top of the QD. Similar phenomena can also be observed for other segregation efficiencies.

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