Investigation of InAs Quantum Dot Deformation During Capping with an InGaAs Layer Using Time-resolved RHEED Measurements

Abstract

We report the characterization of InAs quantum dots (QDs) capped with an InGaAs layer using the time-resolved reflection high energy electron diffraction (RHEED) intensity measurements. The decay rate of the RHEED intensity from the InAs QDs during the capping process reduced with an increase in In composition in the capping layer. The RHEED intensity decay rate, which was determined by the inflection point of differentiated fitting curves of RHEED intensity, can be related with the deformation of the QDs owing to the diffusion of In atoms during the capping process. In addition, cross-sectional transmission electron microscopy observations of the buried QDs revealed that the mean height of the QDs capped with an In 0 . 3 Ga 0 . 7 As layer was larger than that of QDs capped with a GaAs layer. These results suggest that a capping layer with high In composition suppresses the deformation of QDs and results in a red-shift of emission wavelength of the buried QDs.