Lateral Carrier Transfer In Cdxzn1-Xse/Znsyse1-Y Quantum Dot Layers

Lateral carrier transfer is investigated for single CdxZn1-xSe/ZnSySe1-y quantum dots (QD's) in a high-density ensemble by time-resolved spectroscopy. Following nonresonant excitation a significant probability of independent capture of electrons and holes in separate QD's is observed. The subsequent lateral migration of carriers between adjacent QD's leads to a slow decay component of the exciton ground-state luminescence. At low temperatures the lateral carrier transfer is restricted to phonon-assisted inter-QD tunneling, resulting in migration times of the order of several nanoseconds. The role of independent carrier capture is suppressed at high excitation densities or increased temperatures, enabling thermally activated migration.