Influence of an ultrathin GaAs interlayer on the structural properties of InAs/InGaAsP/InP (001) quantum dots investigated by cross-sectional scanning tunneling microscopy

Cross-sectional scanning tunneling microscopy is used to study at the atomic scale how the structural properties of InAs/InGaAsP/InP quantum dots (QDs) are modified when an ultrathin (0–1.5 ML) GaAs interlayer is inserted underneath the QDs. Deposition of the GaAs interlayer suppresses the influence of the As/P exchange reaction on QD formation and leads to a planarized QD growth surface. A shape transition from quantum dashes, which are strongly dissolved during capping, to well defined QDs takes place when increasing the GaAs interlayer thickness between 0 and 1.0 ML. Moreover, the GaAs interlayer allows the control of the As/P exchange reaction, reducing the QD height for increased GaAs thicknesses above 1.0 ML, and decreases the QD composition intermixing, producing almost pure InAs QDs