Excited state spectroscopy of excitons in single quantum dots

We describe the results of a photoluminescence study of quantum dots which are formed by interface fluctuations in narrow GaAs/AlAs single quantum wells. The photoluminescence measurements were made with lateral spatial resolution ranging from the macroscopic down to the optical near-field regime. For spatial resolution below a few square microns the photoluminescence from individual quantum dots is resolved. Photoluminescence excitation spectroscopy is used to study the excited state spectrum of an exciton bound in a single quantum dot.