Role of Thin GaAs Interlayer on InAs Quantum Dots Grown on InGaAsP/InP

The role of increasing GaAs thickness (0-3 nm) to improve the optical quality and tune the emission wavelength of InAs quantum dots (QDs) grown on GaInAsP buffer on (100) InP substrate by metalorganic chemical vapor deposition was studied. The growth of a very thin (0.3 nm-0.6 nm) GaAs interlayer between GaInAsP buffer and InAs QDs layer reduced the mean height and size fluctuation of InAs QDs by suppressing the As/P exchange reaction. As the GaAs interlayer thickness increased further, the surface started to be roughened with formation of dips and trenches. The InAs QDs inclined to agglomerate around the dips and trenches and the improved optical quality of InAs QDs due to insertion of a thin GaAs layer started to disappear. A blue-shift of the peak emission wavelength of InAs QDs from 1533 nm to 1467 nm was also observed as the GaAs interlayer thickness increased from 0.3 nm to 0.6 nm but there was no further blue-shift with further increase of the GaAs interlayer thickness.