Structural and optical properties of In0.5Ga0.5As/GaAs quantum dots in an In0.1Ga0.9As well using repeated depositions of InAs/GaAs short-period superlattices for the application of optical communication

Abstract

We report structural and optical properties of In0.5Ga0.5As/GaAs quantum dots (QDs) in a 100 angstrom-thick In0.1Ga0.9As well grown by repeated depositions of InAs/GaAs short-period superlattices with atomic force microscope, transmission electron microscope (TEM) and photoluminescence (PL) measurement. The QDs in an InGaAs well grown at 510 degrees C were studied as a function of n repeated deposition of 1 monolayer thick InAs and 1 monolayer thick GaAs for n = 5 - 10. The heights, widths and densities of dots are in the range of 6-22.0nm, 40-85nm, and 1.6-1.1 x 10(10)/cm(2), respectively, as n changes from 5 to 10 with strong alignment along [1-10] direction. Flat and pan-cake-like shape of the QDs in a well is found in TEM images. The bottoms of the QDs are located lower than the center of the InGaAs well. This reveals that there was intermixing-interdiffusion-of group III materials between the InGaAs QD and the InGaAs well during growth. All reported dots show strong 300 K-PL spectrum, and 1.276 mu m (FWHM: 32.3 meV) of 300 K-PL peak was obtained in case of 7 periods of the QDs in a well, which is useful for the application to optical communications. (c) 2006 Elsevier B.V. All rights reserved.