Photoluminescence and electromodulation study of InAs/GaAs quantum dots

Abstract

Photoluminescence (PL) and contactless electroreflectance (ER) spectra of InAs quantum dots (QDs) grown on GaAs substrates using either the standard Stranski-Krastanow (SK) method or the atomic layer epitaxy (ALE) method are compared. The PL measurements were carried out at temperatures between 8 K and 150 K, and the ER measurements between 90 K and 295 K. The PL peak energies correlate well with the lowest energy transition feature in the ER, spectra. Signals from the wetting layers are also observed in the ER spectra near the GaAs bandgap energy. The PL and ER linewidths are narrower for the ALE QDs than for the SK QDs, indicating a better size uniformity. In addition, higher energy quantum-dot transitions are observed in the ER. spectra of ALE QDs, which is consistent with a better size uniformity.