1.46 μm room-temperature emission from InAs/InGaAs quantum dot nanostructures

Abstract:

We present a study on InAs/InGaAs QDs nanostructures grown by molecular beam epitaxy on InGaAs metamorphic buffers, that are designed so as to determine the strain of QD and, then, to shift the luminescence emission towards the 1.5 μm region (QD strain engineering). Moreover, we embed the QDs in InAlAs or GaAs barriers in addition to the InGaAs confining layers, in order to increase the activation energy for confined carrier thermal escape; thus, we reduce the thermal quenching of the photoluminescence, which prevents room temperature emission in the long wavelength range. We study the dependence of QD properties, such as emission energy and activation energy, on barrier thickness and height and we discuss how it is possible to compensate for the barrier-induced QD emission blue-shift taking advantage of QD strain engineering. Furthermore, the combination of enhanced barriers and QD strain engineering in such metamorphic QD nanostructures allowed us to obtain room temperature emission up to 1.46 μm, thus proving how this is a valuable approach in the quest for 1.55 gmm room temperature emission from QDs grown on GaAs substrates. The work has been partially supported by the “SANDiE” Network of Excellence of EU(contract no. NMP4-CT-2004-500101). The AFM characterization has been carried out at CIM, University of Parma.