Symmetry reduction in multiband Hamiltonians for semiconductor quantum dots: The role of interfaces and higher energy bands

The role of interfaces and higher bands on the electronic structure of embedded semiconductor quantum dots (QDs) was investigated. The term in the multiband k·p Hamiltonian that captures the effect of interface band mixing was derived starting from the microscopic theory. It was shown, analytically and numerically, that, with such a term included, the right symmetry of the QD system can be captured. It leads to splitting of otherwise degenerate energy levels of the order of several meV. The inclusion of additional higher bands beyond the ones from the standard eight-band model also leads to the reduction of symmetry from an artificially high one to the true atomistic symmetry of the system, however their quantitative effect is weaker. These results prove that the multiband k·p Hamiltonians are fully capable of describing the correct symmetry of a QD.