Abstract

Our samples were grown by molecular beam epitaxy (MBE) on a semi-insulating GaAs substrate. The microdisks consist of a 5 µm diameter disk and a pedestal area. The self-assembled InAs QDs were grown in the center of the 200 nm disk region. The QD density of the sample was ≤ 10⁸ cm⁻². Details of the microdisk structure and the processing can be found in.¹ The samples are mounted in a He gas flow cryostat (4 - 300 K). Optical pumping is performed with a continuous-wave Ti-sapphire laser operating at 760 nm, generating free electron-hole pairs in the GaAs layer. Excitation and collection was done through the same objective in normal direction. Due to the low QD density, in average less than one QD at a time was within the laser spot. The collected PL was dispersed by a 30 cm spectrometer and detected by a charge coupled device (CCD) detector for measurements of optical spectra or by a Hanbury Brown and Twiss (HBT) setup for photon correlation measurements (time resolution 420 ps).

© 2001 Optical Society of America