Optical characterization of Nitrided InAs/GaAs quantum dots grown by MBE

Self-assembled InAs/GaAs quantum dots (QD) are extensively studied for their potential application in optoelectronic devices. In this paper, we report the influence of QD growth rate on the optical properties of InAs/GaAs QDs under their exposure to a Nitrogen plasma. The samples under study are grown by molecular beam epitaxy and characterized by photoluminescence spectroscopy (PL). For capped unnitrided QDs, the increase in InAs growth rate is accompanied by an increase in PL emission energy and PL full width at half maximum (FWHM). Under nitridation, it was found that the incorporation of Nitrogen (N) strongly affected the QD emission and showed a significant redshift of the photoluminescence peak emission. In addition, PL FWHM decreases as the growth rate of InAs increases. The temperature dependence of the PL peak energy of the unnitrided and nitrided QDs exhibits a V shape associated to the carrier localization phenomenon induced by the spatially fluctuating potential. This behavior is confirmed by using the localized state ensemble (LSE) theoretical model. In addition, the results suggest that nitridation aims to reduce the size distribution of QDs and leads to their homogenization compared to the case of inhomogeneous distribution in the absence of Nitrogen. These results are a particularly promising method for realizing QD lasers, which require the use of low QD size and high density with minimal size dispersion.