Fine structure of two-electron states in single and double quantum dots

TL;DR

This paper theoretically investigates the fine structure of two-electron triplet states in quantum dots, deriving analytical expressions for energy splittings caused by spin-orbit interactions, and analyzing their effects on photoluminescence spectra.

Contribution

It introduces new analytical formulas for the splittings of two-electron states in quantum dots considering spin-orbit effects and inversion asymmetry.

Findings

Spin degeneracy of triplet states is fully lifted by spin-orbit interaction.

Derived analytical expressions describe energy splittings in single and double quantum dots.

Photoluminescence spectra reveal the fine structure of two-electron states.

Abstract

Energy spectrum fine structure of triplet two-electron states is investigated theoretically. Spin-orbit interaction induced terms in the effective Hamiltonian of electron-electron interaction are derived for zinc-blende lattice semiconductor nanostructures: quantum wells and quantum dots. The effects of bulk and structural inversion asymmetry are taken into account. Simple analytical expressions describing the splittings of the two-electron states localized in a single quantum dot and in a lateral double quantum dot are derived. The spin degeneracy of triplet states is shown to be completely lifted by the spin-orbit interaction. An interplay of the conduction band spin splitting and the spin-orbit terms in electron-electron interaction is discussed. The photoluminescence spectra of hot trions and of doubly charged excitons are calculated and are shown to reveal the fine structure of two-electron states.