Radiative lifetimes of single excitons in semiconductor quantum dots - manifestation of the spatial coherence effect

Using time correlated single photon counting combined with temperature depe ndent diffraction limited confocal photoluminescence spectroscopy we accura tely determine, for the first time, the intrinsic radiative lifetime of sin gle excitons confined within semiconductor quantum dots. Their lifetime is one (two) orders of magnitude longer than the intrinsic radiative lifetime of single excitons confined in semiconductor quantum wires (wells) of compa rable confining dimensions. We quantitatively explain this long radiative t ime in terms of the reduced spatial coherence between the confined exciton dipole moment and the: radiation electromagnetic field. (C) 2001 Elsevier S cience Ltd. All rights reserved.