The improvement of InAs/GaAs quantum dot properties capped by Graphene

Abstract

InAs self‐assembled quantum dots (QDs) were grown by molecular beam epitaxy on (001) GaAs substrate. Uncapped and capped QDs with GaAs and graphene layers were studied using atomic force microscopy and Raman spectroscopy. Graphene multi‐layer was grown by chemical vapor deposition and transferred on InAs/GaAs QDs. It is well known that the presence of a cap layer modifies the size, shape, and density of the QDs. According to the atomic force microscopy study, in contrast to the GaAs capped sample, which induce a dramatic decrease of the density and height of dots, graphene cap layer sample presents a slight influence on the surface morphology and the density of the islands compared with the uncapped one. The difference shown in the Raman spectra of the samples is due to change of strain and alloy disorder effects on the QDs. Residuals strain and the relaxation coefficients have been investigated. All results confirm the best crystalline quality of the graphene cap layer dots sample relative to the GaAs capped one. So graphene can be used to replace GaAs in capping InAs/GaAs dots. To our knowledge, such study has not been carried out until now. Copyright © 2013 John Wiley & Sons, Ltd.

Enhanced Performance of In(Ga)As QD Based Optoelectronic Devices through Improved Interface Quality between QD and Matrix Material

“…Hence, the InGaAs QD exhibited a lower phonon energy (221 cm −1 ≈27.4 meV) compared to that of InAs QD (224 cm −1 ≈27.77 meV). It is a clear indication of higher In‐content and higher strain‐relaxation in case of InGaAs QD …”

“…It is a clear indication of higher In-content and higher strain-relaxation in case of InGaAs QD. [30,33] The interface defects act as the optically inactive (dark) states at low temperature. However, they may take part in the carrier recombination process at intermediate temperatures, circumventing the phonon-bottleneck effect, which significantly affect the average PL lifetime.…”

Recent advances in linear and nonlinear Raman spectroscopy. Part VIII

“…They concluded that graphene can be used to replace GaAs in capping InAs/GaAs dots. [114] Ribeiro-Soares and coworkers used Raman to characterize the stable carbon materials found in a special type of soil, named Terra Preta de Indio (Indian Dark Earths). They show that the tangential stretching mode (G band) and the disorder-induced mode (D band) can be analyzed in comparison with laboratory-produced amorphous carbons at different degrees of disorder used as reference materials.…”

“…Rezgui and coworkers grew InAs self‐assembled quantum dots (QDs) by molecular beam epitaxy on (001) GaAs substrate and then compared uncapped and capped QDs with GaAs and graphene layers using atomic force microscopy and Raman spectroscopy. They concluded that graphene can be used to replace GaAs in capping InAs/GaAs dots . Ribeiro‐Soares and coworkers used Raman to characterize the stable carbon materials found in a special type of soil, named Terra Preta de Indio (Indian Dark Earths).…”

Raman scattering study on Sb spray InAs/GaAs quantum dot nanostructure systems

“…In addition, another important method is by embedding other compositions in an InGaAs matrix [11][12][13], which results in the increased aspect ratio of the QDs and hence reduced strain inside the QDs, causing a redshift in the emission. The effect of an alternative matrix layer has also been investigated for InAs/GaAs QDs capped with other materials, such as InGaAsN [14] and Graphene [15]. The inclusion of antimony (Sb) is an interesting approach that can be used for InAs/GaAs QD structure tuning.…”