Cross-sectional nanophotoluminescence studies of Stark effects in self-assembled quantum dots

By using a cross-sectional geometry, we show the capability to perform sing le-dot spectroscopy in self-assembled quantum dots using far-field optics. By using this method, we study the quantum-confined Stark effect in self-as sembled quantum dots. For single-stack quantum dots (QDs), we find that the spectra are redshifted with an increase in electric field. For vertically coupled double-stack quantum dots, while most of the QDs are redshifted, so me QDs show blueshifted spectra, which can be interpreted as an evidence of coupled QD molecules. (C) 2000 American Institute of Physics. [S0003-6951( 00)02106-9].