scholarly journals Atomic scale investigations on CdxZn1−xSe quantum dots: Correlation between the composition and emission properties

2014 ◽  
Vol 105 (5) ◽  
pp. 053103 ◽  
Author(s):  
H. Benallali ◽  
T. Cremel ◽  
K. Hoummada ◽  
D. Mangelinck ◽  
R. André ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Atomic Scale ◽  
Emission Properties

High-Temperature Synthesis of CdSe-Based Core/Shell, Core/Shell/Shell, and Core/Graded-Shell Nanoplatelets for Stable and Efficient Narrowband Emitters

2019 ◽  
Author(s):  
Aurelio A. Rossinelli ◽  
Henar Rojo ◽  
Aniket S. Mule ◽  
Marianne Aellen ◽  
Ario Cocina ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Temperature ◽  
Equilibrium Shape ◽  
Size Variation ◽  
Crystal Defects ◽  
Atomic Scale ◽  
Quantum Yields ◽  
Core Shell ◽  
Compositional Gradient ◽  
High Quality

<div>Colloidal semiconductor nanoplatelets exhibit exceptionally narrow photoluminescence spectra. This occurs because samples can be synthesized in which all nanoplatelets share the same atomic-scale thickness. As this dimension sets the emission wavelength, inhomogeneous linewidth broadening due to size variation, which is always present in samples of quasi-spherical nanocrystals (quantum dots), is essentially eliminated. Nanoplatelets thus offer improved, spectrally pure emitters for various applications. Unfortunately, due to their non-equilibrium shape, nanoplatelets also suffer from low photo-, chemical, and thermal stability, which limits their use. Moreover, their poor stability hampers the development of efficient synthesis protocols for adding high-quality protective inorganic shells, which are well known to improve the performance of quantum dots. <br></div><div>Herein, we report a general synthesis approach to highly emissive and stable core/shell nanoplatelets with various shell compositions, including CdSe/ZnS, CdSe/CdS/ZnS, CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S, and CdSe/ZnSe. Motivated by previous work on quantum dots, we find that slow, high-temperature growth of shells containing a compositional gradient reduces strain-induced crystal defects and minimizes the emission linewidth while maintaining good surface passivation and nanocrystal uniformity. Indeed, our best core/shell nanoplatelets (CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S) show photoluminescence quantum yields of 90% with linewidths as low as 56 meV (19.5 nm at 655 nm). To confirm the high quality of our different core/shell nanoplatelets for a specific application, we demonstrate their use as gain media in low-threshold ring lasers. More generally, the ability of our synthesis protocol to engineer high-quality shells can help further improve nanoplatelets for optoelectronic devices.</div>

Carbon Nanotubes, Quantum Dots and Dendrimers as Potential Nanodevices for Nanotechnology Drug Delivery Systems

2013 ◽  
Vol 6 (3) ◽  
pp. 2113-2124
Author(s):  
Prashant Malik ◽  
Neha Gulati ◽  
Raj Kaur Malik ◽  
Upendra Nagaich
Keyword(s):  
Carbon Nanotubes ◽  
Drug Delivery ◽  
Quantum Dots ◽  
Self Assembly ◽  
Drug Delivery Systems ◽  
Delivery Systems ◽  
Atomic Scale ◽  
Sustained Drug Delivery ◽  
Pharmaceutical Nanotechnology ◽  
Conventional Device

Nanotechnology deal with the particle size in nanometers. Nanotechnology is ranging from extensions of conventional device physics to completely new approaches based upon molecular self assembly, from developing new materials with dimensions on the nanoscale to direct control of matter on the atomic scale. In nanotechnology mainly three types of nanodevices are described: carbon nanotubes, quantum dots and dendrimers. It is a recent technique used as small size particles to treat many diseases like cancer, gene therapy and used as diagnostics. Nanotechnology used to formulate targeted, controlled and sustained drug delivery systems. Pharmaceutical nanotechnology embraces applications of nanoscience to pharmacy as nanomaterials and as devices like drug delivery, diagnostic, imaging and biosensor materials. Pharmaceutical nanotechnology has provided more fine tuned diagnosis and focused treatment of disease at a molecular level.    

Emission Properties from ZnO Quantum Dots Dispersed in SiO[sub 2] Matrix

2011 ◽  
Author(s):  
Shrabani Panigrahi ◽  
Durga Basak ◽  
Alka B. Garg ◽  
R. Mittal ◽  
R. Mukhopadhyay
Keyword(s):  
Quantum Dots ◽  
Emission Properties ◽  
Zno Quantum Dots

Relaxation-induced lattice misfits and their effects on the emission properties of InAs quantum dots

2007 ◽  
Vol 18 (35) ◽  
pp. 355401 ◽  
Author(s):  
J F Chen ◽  
Y Z Wang ◽  
C H Chiang ◽  
R S Hsiao ◽  
Y H Wu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Inas Quantum Dots ◽  
Emission Properties

scholarly journals Effect of InAs quantum dots capped with GaAs on atomic-scale ordering in Ga0.5In0.5P

2019 ◽  
Vol 125 (5) ◽  
pp. 053104
Author(s):  
P.-Y. Su ◽  
H. Liu ◽  
R. M. S. Kawabata ◽  
E. C. Weiner ◽  
R. Jakomin ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Atomic Scale ◽  
Inas Quantum Dots

Growth and Overgrowth of Ge/Si Quantum Dots: An Observation by Atomic Resolution HAADF-STEM Imaging

2004 ◽  
Vol 832 ◽  
Author(s):  
Dan Zhi ◽  
Paul A. Midgley ◽  
Rafal E. Dunin-Borkowski ◽  
Bruce A. Joyce ◽  
Don W. Pashley ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Direct Analysis ◽  
Lateral Spreading ◽  
Dark Field ◽  
Atomic Scale ◽  
Wetting Layer ◽  
Compositional Evolution ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
Self Assembled

ABSTRACTThe formation of self-assembled quantum dots (QD) is of increasing interest for applications in optical, nanoelectronic, biological and quantum computing systems. From the perspective of fabrication technology, there are great advantages if the whole device can be made using a single Si substrate. Furthermore, GeSi is a model semiconductor system for fundamental studies of growth and material properties. In practice, as the MBE growth of heterostructures is inherently a non-equilibrium process, the formation of self-assembled nanostructures is both complex and sensitive to growth and overgrowth conditions. The morphology, structure and composition of QDs can all change during growth. It is therefore crucial to understand their structures at different stages of growth at the atomic scale. Here, the characterization of QD growth using high-resolution high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) imaging is presented. Both the formation of uncapped QDs and the effect of the encapsulation are investigated, and the morphological and compositional evolution of the QDs and wetting layers are observed directly at the atomic scale for the first time. During encapsulation, the Ge content in the centres of the QD remains unchanged, despite significant intermixing, lateral spreading and a laterally inhomogeneous Ge distribution inside the Ge QD. The initial non-uniform wetting layer for the uncapped Ge QD becomes uniform after encapsulation, and a 3-monolayer-thick core with ∼ 60% Ge content is formed in the 2 nm-thick wetting layer with an average Ge content of ∼ 30%. The results were obtained by direct analysis of the Z-contrast STEM imaging without involving complex image simulations.

Effects of thermal annealing on the emission properties of type-II InAs/GaAsSb quantum dots

2009 ◽  
Vol 94 (5) ◽  
pp. 053101 ◽  
Author(s):  
Yu-An Liao ◽  
Wei-Ting Hsu ◽  
Pei-Chin Chiu ◽  
Jen-Inn Chyi ◽  
Wen-Hao Chang
Keyword(s):  
Quantum Dots ◽  
Thermal Annealing ◽  
Type Ii ◽  
Emission Properties

Atomic scale characterization of buried InxGa1−xAs quantum dots using pulsed laser atom probe tomography

2008 ◽  
Vol 92 (23) ◽  
pp. 233115 ◽  
Author(s):  
M. Müller ◽  
A. Cerezo ◽  
G. D. W. Smith ◽  
L. Chang ◽  
S. S. A. Gerstl
Keyword(s):  
Quantum Dots ◽  
Atom Probe Tomography ◽  
Pulsed Laser ◽  
Atom Probe ◽  
Atomic Scale ◽  
Scale Characterization
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