Electron and hole spin dynamics in semiconductor quantum dots

Abstract

We report direct measurement of the spin dynamics of electrons and holes in self-assembled InAs quantum dots (QDs) through polarization-sensitive time-resolved photoluminescence experiments on modulation-doped quantum dot heterostructures. Our measured hole spin decay time is considerably longer than in bulk and quantum well semiconductor systems, indicating that the removal of near degenerate hole states with different spin quantization axes through three-dimensional confinement slows hole spin relaxation in semiconductors. The electron and hole spin decay times we observe (electrons: 120ps; holes: 29ps) are consistent with spin relaxation via phonon-mediated virtual scattering between the lowest two confined levels in the QDs, which have a mixed spin character due to the spin–orbit interaction.