A spin-polarized bi-exciton in a semiconductor quantum dot

We discuss the role of spin-polarized multi-exciton complexes in the emission spectra of semiconductor quantum dots. The spin-polarized bi-exciton complex composed of two spin-polarized electrons and two spin-polarized holes confined in a single, parabolic, self-assembled quantum dot is discussed in detail. The configuration-interaction approach is used to compute the energies, wavefunctions, and emission spectra as a function of the magnetic field. It is shown that the spin-polarized bi-exciton emission spectrum differs from the unpolarized spectrum due to the Pauli blocking and exchange interactions. The emission from spin-polarized bi-exciton allows for the measurement of ground and excited single-exciton states, and its magnetic field dependence allows for the differentiation of the spin-polarized bi-exciton and tri-exciton spectrum.