InAs/GaInP self-assembled quantum dots: molecular beam epitaxial growth and optical properties

Abstract

We studied the growth of self-assembled InAs quantum dots (QDs) on GaInP using solid source molecular beam epitaxy (MBE) with the aim of reducing the thermionic escape of bound carriers by burying the QDs in large bandgap materials such as GaInP. The density and size of QDs were measured by atomic force microscopy (AFM). This showed that InAs QDs were formed on GaInP when less than 0.15 monolayers (ML) of InAs was deposited, unlike the formation of InAs QDs on GaAs. The critical thickness of InAs layers for the onset of QD formation increased systematically when a very thin GaAs interlayer was deposited onto the InGaP surface before the formation of the InAs QD layer. When a 10 ML GaAs overlayer was introduced on top of the QD layer, clear photoluminescence (PL) signals were observed from these QDs in the GaInP matrix at room temperature. The good correspondence between the AFM image and the PL spectra indicates that the QD shape is kept in the GaInP matrix without appreciable intermixing.