Effect of random field fluctuations on excitonic transitions of individualCdSe quantum dots

The quantum confined Stark effect is observed for quantum dots (QD's) expos ed to randomly fluctuating electric fields in epitaxial structures. These f ields, attributed to charges localized at defects in the vicinity of the QD 's, lead to a jitter in the emission energies of individual QD's. This jitt er has typical frequencies of below about 1 Hz and is characteristic for ea ch QD thus providing a unique means to unambiguously identify the emission spectra of single QD's. Up to eight lines are identified for individual QD' s and attributed to excitonic, biexcitonic, and LO-phonon-assisted transiti ons. The intensity of the LO-phonon replica is surprisingly large correspon ding to Huang-Rhys factors of about one.