Lateral Coupling of Self-Assembled Quantum Dots Studied by Near-Field Spectroscopy

1999 ◽  
Vol 571 ◽  
Author(s):  
H.D. Robinson ◽  
B.B. Goldberg ◽  
J.L. Merz
Keyword(s):  
Quantum Dots ◽  
Additional Data ◽  
High Spatial Resolution ◽  
Large Fraction ◽  
Near Field ◽  
Localized States ◽  
Emission Lines ◽  
Lateral Coupling ◽  
Self Assembled ◽  
Density Regime

ABSTRACTLateral coupling between separate quantum dots has been observed in a system of In0.55A10.45As self-assembled quantum dots. The experiment was performed by taking photoluminescence excitation (PLE) spectra in the optical near-field at 4.2 K. The high spatial resolution afforded by the near-field technique allows us to resolve individual dots in a density regime where interactions between neighboring dots become apparent. In the PLE spectra, narrow resonances are observed in the emission lines of individual dots. A large fraction of these resonances occur simultaneously in several emission lines, originating from different quantum dots. This is evidence of interdot scattering of carriers, which additional data show to be mediated by localized states at energies below the wetting layer exciton energy. A very rich phonon spectrum generated by the complicated interfaces between barrier and dot material is also evident in the data.

Near Field Optical Spectroscopy of GaN/AlN Quantum Dots

2004 ◽  
Vol 831 ◽  
Author(s):  
A. Neogi ◽  
B. P. Gorman ◽  
H. Morkoç ◽  
T. Kawazoe ◽  
M. Ohtsu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Near Field ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Spacer Layer Thickness ◽  
Spacer Layer ◽  
Lateral Coupling ◽  
Self Assembled ◽  
Spectrally Resolved

ABSTRACTWe investigate the spatial distribution and emission properties of self-assembled GaN/AlN quantum dots. High-resolution transmission electron microscopy reveals near vertical correlation among the GaN dots due to a sufficiently thin AlN spacer layer thickness, which allows strain induced stacking. Scanning electron and atomic force microscopy show lateral coupling due to a surface roughness of ∼ 50–60 nm. Near-field photoluminescence in the illumination mode (both spatially and spectrally resolved) at 10 K revealed emission from individual dots, which exhibits size distribution of GaN dots from localized sites in the stacked nanostructure. Strong spatial localization of the excitons is observed in GaN quantum dots formed at the tip of self-assembled hexagonal pyramid shapes with six [101 1] facets.

scholarly journals Near-field photoluminescence spectroscopy of localized states in InGaAsN alloys

2001 ◽  
Vol 692 ◽  
Author(s):  
A. M. Mintairov ◽  
P. A. Blagnov ◽  
T. Kosel ◽  
J. L. Merz ◽  
V. M. Ustinov ◽  
...  
Keyword(s):  
Optical Properties ◽  
Quantum Dot ◽  
Near Field ◽  
Zeeman Splitting ◽  
Localized States ◽  
Emission Lines ◽  
Structural And Optical Properties ◽  
Dramatic Difference ◽  
Nitrogen Excess ◽  
Narrow Emission

AbstractWe used near-field magneto-photoluminescence scanning microscopy to study structural and optical properties of quantum-dot-like compositional fluctuations in GaAsN and InGaAsN alloys. We show that these fluctuations manifest themselves by the appearance of narrow emission lines (halfwidth 0.5−2 meV) at temperatures below 70K. We estimated the size, density, and nitrogen excess of individual compositional fluctuations (clusters), revealing phaseseparation effects in the distribution of nitrogen in GaAsN and InGaAsN. We found a dramatic difference in the Zeeman splitting of cluster lines between GaAsN and InGaAsN, indicating a strong effect of In on the exciton g-factor.

Time-Resolved Emission from Self-Assembled Single Quantum Dots Using Scanning Near-Field Optical Microscope

1999 ◽  
Vol 38 (Part 2, No. 12A) ◽  
pp. L1460-L1462 ◽  
Author(s):  
Madoka Ono ◽  
Kazunari Matsuda ◽  
Toshiharu Saiki ◽  
Kenichi Nishi ◽  
Takashi Mukaiyama ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Near Field ◽  
Optical Microscope ◽  
Single Quantum ◽  
Time Resolved ◽  
Single Quantum Dots ◽  
Self Assembled

Strain-induced localized states within the matrix continuum of self-assembled quantum dots

2009 ◽  
Vol 95 (2) ◽  
pp. 023108 ◽  
Author(s):  
Voicu Popescu ◽  
Gabriel Bester ◽  
Alex Zunger
Keyword(s):  
Quantum Dots ◽  
Localized States ◽  
The Matrix ◽  
Self Assembled

scholarly journals Self-assembled Star-shaped Chiroplasmonic Gold Nanoparticles for Ultrasensitive Chiro-immunosensor of Viruses

2017 ◽  
Author(s):  
Syed Rahin Ahmed ◽  
Éva Nagy ◽  
Suresh Neethirajan
Keyword(s):  
Quantum Dots ◽  
Avian Influenza ◽  
Influenza A ◽  
Limit Of Detection ◽  
Optical Rotation ◽  
Near Field ◽  
Near Field Optics ◽  
Self Assembling ◽  
Self Assembled ◽  
Chiral Nanostructures

Near field optics and optical tunneling light-matter interaction in the superstructure of chiral nanostructures and semiconductor quantum dots exhibit strong optical rotation activity that may open a new window for chiral-based bioanalytes detection. Herein we report an ultrasensitive, chiro-immunosensor using superstructure of chiral gold nanohybrids (CAu NPs) and quantum dots (QDs). Self-assembling techniques were employed to create asymmetric plasmonic chiral nanostructures for extending the spectral range of circular dichroism (CD) response for obtaining superior plasmonic resonant coupling with the QDs excitonic state; this may help to achieve lower the limit of detection (LOD) values. As a result, the designed probe exhibited avian influenza A (H5N1) viral concentration at picomolar level, a significant improvement in sensitivity in comparison to a non-assembled CAu NPs based chiroassay. The practicability of the proposed sensing system was successfully demonstrated on several virus cultures including, avian influenza A (H4N6) virus, fowl adenovirus and coronavirus in blood samples. The results of our study highlights that exciton-plasmon interaction changes chirality and the self-assembled nanostructures are an efficient strategy for enhancing the sensitivity of plasmonic nanosensors.

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