Influence of GaAs/InAs quasi-monolayer on the structural and optical properties of InAs/GaAs quantum dots

InAs QDs on strained {GaAs/InAs} quasi-monolayer (QML) with an alternative growth mechanism were grown by molecular beam epitaxy (MBE). The properties of quantum dots (QDs) were investigated by transmission electron microscopy (TEM), photoluminescence (PL), and photoreflectance (PR). TEM images and PR spectra of InAs QDs with strained {GaAs/InAs} QML only show a lack of the wetting layer (WL) compared with conventional InAs QDs sample. The Photoluminescence (PL) emission peak of the InAs QDs with 10 periods strained {GaAs/InAs} QML is red-shifted by 180 meV at 10 K relative to the reference InAs QDs sample which has no {GaAs/InAs} QML. The InAs QDs with 10 periods {GaAs/InAs} QML also show a string PL emission with 1.32 mum at room temperature. Similar to the various periods of QML in InAs QDs sample, the emission wavelength of InAs QDs changes significantly toward the long wavelength emission. (C) 2003 Elsevier Science B.V. All rights reserved.