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The quantum confined Stark effect is observed for quantum dots (QD's) exposed to randomly fluctuating electric fields in epitaxial structures. These fields, 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 jitter has typical frequencies of below about 1 Hz and is characteristic for each 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 transitions. The intensity of the LO-phonon replica is surprisingly large corresponding to Huang-Rhys factors of about one

We identify fundamental mechanisms of electron escape from self-organized InAs quantum dots ͑QD's͒ in a vertical electric field by time-resolved capacitance spectroscopy. Direct tunneling and a thermally activated escape process are observed. The QD electron ground and first-excited states are concluded to be located ϳ190 and ϳ96 meV below the GaAs matrix conduction band, respectively. Our experimental results and their interpretation are in good agreement with eight-band k•p calculations and demonstrate the importance of tunnel processes.