Time-space-resolved photoluminescence from (Zn,Cd)Se-based quantum structures

Spectroscopic technique which possesses both temporal and spacial resolutio n was developed by combining the pico-second pulsed laser system with the o ptical microscope. By using this technique, the time-resolved photoluminesc ence (TRPL) with micron spatial resolution was performed for the self-organ ized CdSe/ZnSe quantum dots (QDs) fabricated on GaAs(110) crystal surfaces, PL spectra of CdSe/ZnSe with 10 monolayer (ML) deposition thickness were c omposed of two emission bands peaking at 2.6 and 2.2 eV. These bands could be ascribed to the emissions from CdSe quantum wells (QWs) acting as weltin g layers and QDs, respectively. With macroscopic excitation (spot size: 100 mu m). temporal behavior of the omission band of QDs was characterized by multi-exponential decay. However, with microscopic excitation (spot size: 5 mu m). it was found that both spectrum shapes and PL lifetimes have change d with sweeping the location of focus. Especially, the lifetimes were quite valuable and were well fitted by the single exponential decay, These resul ts suggest that the radiative lifetime differs very much depending on the d egree of exciton localization. (C) 2000 Published by Elsevier Science B.V. All rights reserved.