Electronic Structure of CdSe/CdXZn1-XS Core/Shell Quantum Dots

2011 ◽  
Vol 284-286 ◽  
pp. 2037-2040
Author(s):  
Guo Zhi Jia ◽  
Yun Feng Wang ◽  
Jiang Hong Yao
Keyword(s):  
Quantum Dots ◽  
Electronic Structure ◽  
Kinetic Energy ◽  
Electronic Structures ◽  
Band Offset ◽  
Core Shell ◽  
Structure Parameters ◽  
Transition Energies ◽  
Mass Approximation ◽  
Energy Band Offset

The electronic structures of CdSe/CdxZn1-xS core/shell quantum dots are investigated systematically using the effective-mass approximation method. The calculated results have shown that both of the electron and hole are completely localized at the range of core, which can be ascribed to the large energy band offset in valence band and conduction band. The carriers appear in the region of core or shell, which mainly depend on the competition between the kinetic energy and the potential energy in the heterostrucuture QDs. The transition energies can be widely tuned by the changing the structure parameters.

Single-charge transport through hybrid core–shell Au-ZnS quantum dots: a comprehensive analysis from a modified energy structure

Nanoscale ◽  
2021 ◽  
Author(s):  
Tuhin Shuvra Basu ◽  
Simon Diesch ◽  
Ryoma Hayakawa ◽  
Yutaka Wakayama ◽  
Elke Scheer
Keyword(s):  
Quantum Dots ◽  
Electronic Structure ◽  
Carrier Transport ◽  
Comprehensive Analysis ◽  
Energy Structure ◽  
Core Shell ◽  
Single Charge ◽  
Scanning Tunnelling Microscope ◽  
Single Carrier ◽  
Scanning Tunnelling

We examined the modified electronic structure and single-carrier transport of individual hybrid core–shell metal–semiconductor Au-ZnS quantum dots using a scanning tunnelling microscope.

scholarly journals Exciton-Related Raman Scattering, Interband Absorption and Photoluminescence in Colloidal Cdse/Cds Core/Shell Quantum Dots Ensemble

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1274
Author(s):  
Grigor A. Mantashian ◽  
Paytsar A. Mantashyan ◽  
Hayk A. Sarkisyan ◽  
Eduard M. Kazaryan ◽  
Gabriel Bester ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Raman Scattering ◽  
Cross Section ◽  
Core Shell ◽  
Interband Absorption ◽  
Photoluminescence Spectra ◽  
Cds Quantum Dots ◽  
Mass Approximation ◽  
Numerical Discretization ◽  
Size Dispersion

By using the numerical discretization method within the effective-mass approximation, we have theoretically investigated the exciton-related Raman scattering, interband absorption and photoluminescence in colloidal CdSe/CdS core/shell quantum dots ensemble. The interband optical absorption and photoluminescence spectra have been revealed for CdSe/CdS quantum dots, taking into account the size dispersion of the ensemble. Numerical calculation of the differential cross section has been presented for the exciton-related Stokes–Raman scattering in CdSe/CdS quantum dots ensemble with different mean sizes.

Interband Optical Transition Energies in Type-II PbSe/PbS Core/Shell Quantum Dots

2017 ◽  
Vol 6 (1) ◽  
pp. 80-86
Author(s):  
S. N. Saravanamoorthy ◽  
A. John Peter
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Shell Thickness ◽  
Optical Transition ◽  
Hole Pair ◽  
Core Shell ◽  
Type Ii ◽  
Electron Hole ◽  
Transition Energies ◽  
Electron Hole Pair

Electronic and optical properties of Type-II lead based core/shell semiconducting quantum dots are reported. Binding energies of electron–hole pair, optical transition energies and the absorption coefficients are investigated taking into account the geometrical confinement in PbSe/PbS core/shell quantum dot nanostructure. The energies are obtained with the increase of shell thickness for various inner core radii. The probability densities of electron and hole wave functions of radial coordinate of the core PbSe and PbS shell quantum dots are presented. The optical transition energy with the spatial confinement is brought out. The electronic properties are obtained using variational approach whereas the compact density matrix method is employed for the nonlinear optical properties. The results show that (i) a decrease in binding energy is obtained when the shell thickness increases due to more separation of electron–hole pair and (ii) the energy band gap decreases with the increase in the shell thickness resulting in the reduction of the higher energy interband transitions.

A comparison of optical properties of disc-like and spherical quantum dots

2018 ◽  
Vol 27 (03) ◽  
pp. 1850034
Author(s):  
Vildan Üstoğlu Ünal ◽  
Erem Birşey ◽  
Ertan Akşahin
Keyword(s):  
Quantum Dots ◽  
Refractive Index ◽  
Optical Properties ◽  
Optical Absorption ◽  
Electric Field ◽  
Electronic Structures ◽  
Electric Field Effect ◽  
Total Change ◽  
Absorption Increase ◽  
Mass Approximation

The optical properties of quantum dots (QDs) are of interest to many researchers. In this study, the optical coeefficients analyzed include the optical absorption, the refractive index; both the linear and nonlinear cases together with the electric field effect. The electronic structures of the disc-like and spherical QDs are calculated by using the effective-mass approximation. The results show that the total change in the refractive index and the optical absorption increase with increasing QD size, the peaks are shifted with the changing QD size. The nonlinear optical properties increase with the external electric field and the optical intensity. Comparison of QD types shows that the peaks are red-shifted for the disc-like QD and lower than those in the spherical QD case.

scholarly journals Linear and Nonlinear Optical Absorption of CdSe/CdS Core/Shell Quantum Dots in the Presence of Donor Impurity

Atoms ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 75
Author(s):  
Grigor A. Mantashian ◽  
Nare A. Zaqaryan ◽  
Paytsar A. Mantashyan ◽  
Hayk A. Sarkisyan ◽  
Sotirios Baskoutas ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Nonlinear Optical ◽  
Incident Light ◽  
Refractive Index Change ◽  
Core Shell ◽  
The Finite Element Method ◽  
Third Order ◽  
Mass Approximation ◽  
Nonlinear Optical Absorption ◽  
Linear And Nonlinear

Linear and nonlinear optical properties in colloidal CdSe/CdS core/shell quantum dots with different sizes have been theoretically investigated in the framework of effective mass approximation. The electron states in colloidal CdSe/CdS core/shell quantum dots have been calculated using the finite element method. The intraband linear and nonlinear absorption spectra have been calculated for colloidal CdSe/CdS core/shell quantum dots with different sizes. In addition, the dependences of the linear and nonlinear refractive index change on the incident light energy have been calculated. In the last section of the paper the second- and third-order harmonic generation spectra have been presented.

Electronic structure of ZnO/ZnS core/shell quantum dots

2013 ◽  
Vol 555 ◽  
pp. 191-195 ◽  
Author(s):  
Supriya Saha ◽  
Pranab Sarkar
Keyword(s):  
Quantum Dots ◽  
Electronic Structure ◽  
Core Shell

Interface control of electronic and optical properties in IV–VI and II–VI core/shell colloidal quantum dots: a review

2017 ◽  
Vol 53 (6) ◽  
pp. 1002-1024 ◽  
Author(s):  
Youngjin Jang ◽  
Arthur Shapiro ◽  
Maya Isarov ◽  
Anna Rubin-Brusilovski ◽  
Aron Safran ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Electronic Structure ◽  
Chemical Stability ◽  
Interface Design ◽  
Colloidal Quantum Dots ◽  
Core Shell ◽  
Electronic And Optical Properties ◽  
Interface Control

Core/shell heterostructures provide controlled optical properties, tuneable electronic structure, and chemical stability due to an appropriate interface design.

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>

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