Graphene-capped InAs/GaAs quantum dots

Graphene was grown by chemical vapor deposition and successfully transferred onto InAs/GaAs quantum dots (QDs) grown by molecular beam epitaxy on a (001) GaAs substrate. To our knowledge, the hybrid structure of graphene replacing the conventional GaAs layer as a cap layer has not been explored until now. In this work, the authors present the photoluminescence (PL) and Raman spectroscopy study of InAs/GaAs graphene-capped QDs. The Raman measurements show an intense 2D peak at 2704 cm^-1 which is the main characteristic indicating the presence of graphene. The recorded PL at temperature T = 300 K shows two sharp peaks located at 1.177 and 1.191 eV, which is attributed to radiative emission from the quantum dots. These peaks, which are generally very weak in InAs/GaAs quantum dots at this temperature, are instead very intense. The enhancement of the PL emission evidenced electron transfer from the graphene layer to the QDs.