scholarly journals Plasmonic Properties of Bimetallic Quantum Dot Ag@Au Core-Shell Nanostructures Embedded in Non-Absorptive Host Medium

2021 ◽  
Author(s):  
Gashaw Beyene Beyene Kassahun
Keyword(s):  
Quantum Dot ◽  
Field Enhancement ◽  
Visible Spectral Region ◽  
Classical Electrodynamics ◽  
Core Shell ◽  
Core Size ◽  
Static Approximation ◽  
Host Medium ◽  
Shell Nanostructures ◽  
Outer Interface

This studies the plasmonic properties of the bimetallic quantum dot Ag@Au core-shell nanostructures embedded in the non-absorbent host medium. Local field enhancement factor and coefficient of absorption of Ag-core and Au-shell are primarily studied based on quasi-static approximation of classical electrodynamics for 6-10 nm composite radius. In this quantum dot geometry, two set of plasmonic resonances in visible spectral region are observed: the first resonance associated with inner interface of gold (Ag@Au) and the second resonance associated with outer interface of gold (Au@medium). The two plasmonic resonances are close each other and enhanced when the size of composite decreased for a fixed core size while shifted to in opposite direction and the amplitude of peak decreased when the core size is increased for a fixed composite size. For the optimized size of core/composite or shell thickness and other parameters to the desired values, such type of composites are recommended for various applications like; photocatalysis, biomedical, nano-optoelectronics.

scholarly journals High Tunability of Size Dependent Optical Properties of ZnO@M@Au (M = SiO2, In2O3, TiO2) Core/Spacer/Shell Nanostructure

2019 ◽  
Vol 2 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Gashaw Beyene Kassahun
Keyword(s):  
Optical Properties ◽  
Quantum Dot ◽  
Spectral Region ◽  
Shell Shape ◽  
Core Shell ◽  
Gold Content ◽  
Core Size ◽  
Static Approximation ◽  
Size Dependent ◽  
High Tunability

This theoretical work presents a comparative study of high tunability size dependent optical properties of quantum dot/wire triple layered core shell nanostructure based on the quasi-static approximation of classical electrodynamics embedded in a fixed dielectrics function of host matrix. In this paper, local field enhancement factor (LFEF), refractive index and optical absorbance of nanocomposite are analyzed by varying core size, thickness of spacer and shell as well as dielectrics function of the spacer for the size of the nanocomposite with the range of 20 nm to 40 nm. For both quantum dot and quantum wire triple layered core shell nanostructure (CSNS), there are two resonances in visible and near/in infrared spectral region with high tunability. When the shell thickness increase and therefore increasing the gold content, the surface plasmon resonance (SPR) at the outer interface shifts to higher energy (blue-shifted) and at the inner interface weak peaks and shifted to lower energy (red-shifted). All of three optical properties, depend on core size, dielectrics and thickess of spacer, thickness of shell, shape of composite and filling factor. For the same thickness of spacer and shell of the two configurations, cylindrical triple layered CSNS less pronounced and shifted to infrared red (IR) spectral region which is recommendable for biological and photocatalysis application.      

scholarly journals Effect of core size/shape on the plasmonic response of spherical ZnO@Au core-shell nanostructures embedded in a passive host-matrices of MgF2

2020 ◽  
Vol 7 (6) ◽  
pp. 705-719
Author(s):  
Gashaw Beyene ◽  
◽  
Gamachis Sakata ◽  
Teshome Senbeta ◽  
Belayneh Mesfin ◽  
...  
Keyword(s):  
Core Shell ◽  
Core Size ◽  
Shell Nanostructures ◽  
Host Matrices

Binding energies and photoionization cross-sections of donor impurities in GaN/AlxGa1−xN spherical quantum dot under hydrostatic pressure

2020 ◽  
Vol 34 (14) ◽  
pp. 2050153
Author(s):  
Shuo Li ◽  
Lei Shi ◽  
Zu-Wei Yan
Keyword(s):  
Hydrostatic Pressure ◽  
Binding Energy ◽  
Quantum Dot ◽  
Cross Section ◽  
Cross Sections ◽  
Photoionization Cross Section ◽  
Binding Energies ◽  
Core Shell ◽  
Core Size ◽  
Shell Size

In this paper, the binding energy and photoionization cross-section of donor impurity state in [Formula: see text] quantum dot structure are studied theoretically by using variational method. The variation of binding energy and photoionization cross-section with core and shell sizes at different impurity locations under hydrostatic pressure is calculated numerically. The results show that the binding energy decreases monotonously with the core size at different impurity locations for [Formula: see text] core/shell quantum dot. In contrast, for the inverted core/shell quantum dot, the binding energy exhibits different trends with the increase of core size at different impurity locations. But the binding energy decreases monotonically with the shell size for both of them. Moreover, when the photon energy is approximately equal to the donor binding energy, the peak of the photoionization cross-section appears. There will be different peak shifts under different conditions, and its peak intensity increases with the increase of core and shell sizes. When the hydrostatic pressure is applied, the binding energy and the peak strength of the photoionization cross-section increase with the increase of the pressure.

scholarly journals ZnTe/CdSe type-II core/shell spherical quantum dot under an external electric field

2018 ◽  
Vol 3 (1) ◽  
Author(s):  
A. Chafai ◽  
I. Essaoudi ◽  
A. Ainane ◽  
F. Dujardin ◽  
R. Ahuja
Keyword(s):  
Quantum Dot ◽  
Electric Field ◽  
External Electric Field ◽  
Function Approximation ◽  
Charge Carriers ◽  
Conduction Band Edge ◽  
Core Shell ◽  
Electron Effective Mass ◽  
Spherical Quantum Dot ◽  
Shell Nanostructures

We have investigated in the framework of the envelope function approximation and taking into account the dependence of the electron effective mass on radius the energy of an electron inside a ZnTe/CdSecore/shell spherical quantum dot. In order to make the problem more realistic, we describe the conduction band-edge alignment between core and shell materials by a finite height barrier. By applying the Ritz variational principle the effect of the electric field on the electronic states was also examined. Our numerical results show the opportunity to control the energy states position of the charge carriers inside our core/shell nanostructures by controlling the size (core radius, shell thickness) of the nanostructure and the strength of the external electric field. #CORE/SHELL MATERIALS #NANOSTRUCTURES #QUANTUM DOTS #ELECTRIC FIELD

scholarly journals Modeling of the surface plasmon resonance tunability of silver/gold core–shell nanostructures

RSC Advances ◽  
2018 ◽  
Vol 8 (35) ◽  
pp. 19616-19626 ◽  
Author(s):  
Dab Chahinez ◽  
Thomas Reji ◽  
Ruediger Andreas
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Chemical Sensors ◽  
Near Field ◽  
Field Enhancement ◽  
Noble Metal Nanoparticles ◽  
Core Shell ◽  
Shell Nanostructures ◽  
Gold Core ◽  
Resonance Tunability

Tunable plasmonic noble metal nanoparticles are indispensable for chemical sensors and optical near field enhancement applications.

scholarly journals Coupled hard–soft spinel ferrite-based core–shell nanoarchitectures: magnetic properties and heating abilities

2020 ◽  
Vol 2 (8) ◽  
pp. 3191-3201 ◽  
Author(s):  
Marco Sanna Angotzi ◽  
Valentina Mameli ◽  
Claudio Cara ◽  
Anna Musinu ◽  
Claudio Sangregorio ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Shell Thickness ◽  
Spinel Ferrite ◽  
Magnetic Core ◽  
Core Shell ◽  
Core Size ◽  
Shell Nanostructures

The heating abilities of bi-magnetic core–shell nanostructures are studied depending on core size, nature of the shell, and shell thickness.

Influence of Core-Shell Architecture Parameters on Thermal Conductivity of Si-Ge Nanowires

2015 ◽  
Vol 1735 ◽  
Author(s):  
Sevil Sarikurt ◽  
Cem Sevik ◽  
Alper Kinaci ◽  
Justin B. Haskins ◽  
Tahir Cagin
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Performance ◽  
Core Shell ◽  
Core Size ◽  
Dynamic Simulations ◽  
Cross Sectional ◽  
Shell Nanostructures ◽  
Different Temperatures ◽  
Shell Nanowires ◽  
Equilibrium Molecular Dynamic

ABSTRACTIn this work, we investigate the influence of the core-shell architecture on nanowire (1D) thermal conductivity targeting to evaluate its validity as a strategy to achieve a better thermoelectric performance. To obtain the thermal conductivity values, equilibrium molecular dynamic simulations is applied to Si and Ge systems that are chosen to form core-shell nanostructures. To explore the parameter space, we have calculated thermal conductivity values of the Si-core/Ge-shell and Ge-core/Si-shell nanowires at different temperatures for different cross-sectional sizes and different core contents. Our results indicate that (1) increasing the cross-sectional area of pristine Si and pristine Ge nanowire increases the thermal conductivity (2) increasing the Ge core size in the Si-core/Ge-shell structure results in a decrease in the thermal conductivity values at 300 K (3) thermal conductivity of the Si-core/Ge-shell nanowires demonstrates a minima at specific core size (4) no significant variation in the thermal conductivity observed in nanowires for temperature values larger than 300 K (5) the predicted thermal conductivity around 10 W m−1K−1 for the Si and Ge core-shell architecture is still high to get desired ZT values for thermoelectric applications. On the other hand, significant decrease in thermal conductivity with respect to bulk thermal conductivity of materials and pristine nanowires proves that employing core–shell architectures for other possible thermoelectric material candidates would serve valuable opportunities to achieve a better thermoelectric performance.

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