Modelling of density of states and energy level of chalcogenide quantum dots

AbstractQuantum dots (QDs) or semiconductor nanocrystals are luminous materials with unique optical properties that can be fine-tuned by varying the size of the material. Chalcogenide QDs show strong quantum confinements effects owing to the fact that the exciton Bohr radius is much larger than the particle size, and tunable energy bandgap leads to widespread technological interest in near-infrared optical devices. In this communication, one dimensional Cu2SnS3 and PbSexS1-x QDs is modeled by a particle in a box model which was used to compute energies and density of states. The density of states and the energy level of QDs are determined as a function of the strengths of the potential walls of the inner box. The results exhibit that the density of states decreases exponentially with an increase in the energy level of QDs. The density of states at lower energy levels is more significant than what is observed in higher energy levels.

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Synthesis, Properties and Bioimaging Applications of Silver-Based Quantum Dots

International Journal of Molecular Sciences ◽

10.3390/ijms222212202 ◽

2021 ◽

Vol 22 (22) ◽

pp. 12202

Author(s):

Mariya Borovaya ◽

Inna Horiunova ◽

Svitlana Plokhovska ◽

Nadia Pushkarova ◽

Yaroslav Blume ◽

...

Keyword(s):

Quantum Dots ◽

Near Infrared ◽

Semiconductor Nanocrystals ◽

Current Status ◽

Synthesis Properties ◽

Semiconductor Nanomaterials ◽

Electrooptical Properties ◽

Basic Features

Ag-based quantum dots (QDs) are semiconductor nanomaterials with exclusive electrooptical properties ideally adaptable for various biotechnological, chemical, and medical applications. Silver-based semiconductor nanocrystals have developed rapidly over the past decades. They have become a promising luminescent functional material for in vivo and in vitro fluorescent studies due to their ability to emit at the near-infrared (NIR) wavelength. In this review, we discuss the basic features of Ag-based QDs, the current status of classic (chemical) and novel methods (“green” synthesis) used to produce these QDs. Additionally, the advantages of using such organisms as bacteria, actinomycetes, fungi, algae, and plants for silver-based QDs biosynthesis have been discussed. The application of silver-based QDs as fluorophores for bioimaging application due to their fluorescence intensity, high quantum yield, fluorescent stability, and resistance to photobleaching has also been reviewed.

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Tunnel model for quantum liquids

Australian Journal of Chemistry ◽

10.1071/ch9670197 ◽

1967 ◽

Vol 20 (2) ◽

pp. 197

Author(s):

L Oden ◽

D Henderson

Keyword(s):

Energy Level ◽

Critical Region ◽

Hard Sphere ◽

Hard Spheres ◽

Energy Levels ◽

Quantum Fluids ◽

One Dimensional ◽

Simple Liquids ◽

Quantum Liquids ◽

Tunnel Model

In the tunnel model, a fluid is regarded as being composed of lines of molecules which move almost one-dimensionally in lines or tunnels, the walls of which are formed by neighbouring lines of molecules. This model has been used, with good success, to describe the properties of classical hard spheres and classical simple liquids. For quantum fluids the energy levels of a one-dimensional line of molecules must be calculated. This has been done only for a system of hard spheres. For more complicated systems the energy levels must be approximated. In this paper the tunnel model is applied to liquid 4He at absolute zero and to liquid H2. The lowest energy level has been approximated and the hard-sphere energy levels are used to estimate the higher energy levels. The agreement with experiment is generally good except in the critical region.

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Electron transport through two one-dimensional multi-quantum dot arrays coupled to four leads

Modern Physics Letters B ◽

10.1142/s0217984918503335 ◽

2018 ◽

Vol 32 (27) ◽

pp. 1850333 ◽

Cited By ~ 2

Author(s):

Zelong He ◽

Kongfa Chen ◽

Mengchun Lu ◽

Qiang Li

Keyword(s):

Quantum Dots ◽

Quantum Dot ◽

Green’S Function ◽

Green's Function ◽

Energy Levels ◽

Transmission Probability ◽

Function Technique ◽

One Dimensional ◽

Resonance Band ◽

Dc Current

Employing the non-equilibrium Green’s function technique, we have obtained the formula for dc current of two one-dimensional multi-quantum dot arrays, which couple to each other via tunneling coupling between two quantum dots connected to four leads, respectively. The retarded Green’s function is a staircase type, terminating at the four leads. Furthermore, the four quantum dots case is demonstrated. The influence of inter-dot coupling strength and quantum dot energy level on the transmission probability for TL, TM and TN branches is investigated. A non-resonant band is observed. By adjusting energy levels of quantum dots, a resonance emerges in the region of the non-resonance band. The system can be used as a quantum switch.

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OPTICAL PROPERTIES OF POPULATED InAs/GaAs QUANTUM DOTS

International Journal of Nanoscience ◽

10.1142/s0219581x03001280 ◽

2003 ◽

Vol 02 (04n05) ◽

pp. 265-269

Author(s):

JIA-REN LEE ◽

C.-R. LU ◽

W. I. LEE ◽

S. C. LEE

Keyword(s):

Quantum Dots ◽

Optical Properties ◽

Energy Level ◽

Energy Levels ◽

Wetting Layer ◽

Photoluminescence Spectra ◽

Inas Quantum Dots ◽

Different Temperatures ◽

Spectral Profiles ◽

Equal Spacing

The optical properties of InAs/GaAs Quantum Dots have been studied by comparing the photoreflectance and photoluminescence spectra at different temperatures. The photoreflectance relative spectral intensity between the contributions from InAs wetting layer and the GaAs increases with the decreasing of temperature. The photoluminescence spectral profiles consist of contributions from the equal spacing energy levels of the InAs quantum dots. Since the quantum dot transitions were observed in the photoluminescence spectra and the wetting layer transitions were observed in the photoreflectance spectra, we propose that the Fermi level of the system is located between energy level of the wetting layer and the populated energy level of the quantum dots.

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Ligand-Mediated Energy-Level Modification in PbS Quantum Dots as Probed by Density of States (DOS) Spectra

The Journal of Physical Chemistry C ◽

10.1021/acs.jpcc.8b03022 ◽

2018 ◽

Vol 122 (21) ◽

pp. 11570-11576 ◽

Cited By ~ 3

Author(s):

Biswajit Kundu ◽

Amlan J. Pal

Keyword(s):

Quantum Dots ◽

Energy Level ◽

Density Of States ◽

Pbs Quantum Dots

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Antiresonance in electron transport through a four quantum dots system

Modern Physics Letters B ◽

10.1142/s0217984919504281 ◽

2019 ◽

Vol 33 (34) ◽

pp. 1950428 ◽

Cited By ~ 2

Author(s):

Zelong He ◽

Kongfa Chen ◽

Jiyuan Bai ◽

Yadong Li

Keyword(s):

Quantum Dots ◽

Quantum Computing ◽

Energy Level ◽

Theoretical Basis ◽

Energy Levels ◽

Coulomb Interactions ◽

Mathematical Formula ◽

Resonance Band ◽

Narrow Width ◽

Interdot Coupling

A four quantum dots structure is designed. The influence of the interdot coupling strength, energy levels of quantum dots, magnetic flux and intradot Coulomb interactions on the conductance is discussed. An antiresonance point exactly emerges at the location of the energy level of side-coupled quantum dots (SCQD). The conversion between resonance band and antiresonance band can be achieved as parallel-coupled di-quantum dots with or without SCQD, which suggests a physical scheme of an effective quantum switch. The Breit–Wigner resonant and Fano antiresonant peaks may merge into one resonant band. By means of the mathematical formula, we analyze how the resonance band is formed. By varying intradot Coulomb interaction, the resonance band may evolve into a Fano antiresonance with an ultra-narrow width. This study provides theoretical basis for the design of quantum computing devices.

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Modelling of electronic and optical properties of Cu2SnS3 quantum dots for optoelectronics applications

Materials Science-Poland ◽

10.2478/msp-2018-0103 ◽

2019 ◽

Vol 37 (1) ◽

pp. 108-115

Author(s):

M. Irshad Ahamed ◽

K. Sathish Kumar

Keyword(s):

Quantum Dots ◽

Optical Properties ◽

Solar Cell ◽

Quantum Dot ◽

Near Infrared ◽

Infrared Range ◽

Tin Sulfide ◽

Bohr Radius ◽

Energy Bandgap ◽

Near Infrared Range

AbstractCopper tin sulfide (Cu2SnS3) is a unique semiconductor, whose nanocrystals have attracted researchers’ attention for its tunable energy bandgap and wavelength in visible and near infrared range. Quantum dots which are fabricated from this material are highly suitable for optoelectronics and solar cell applications. This paper discusses the tunable energy bandgap, exciton Bohr radius and wavelength range of wurtzite structure of Cu2SnS3 quantum dots to assess the opportunity to use them in optoelectronics applications. The considerations show that the mole fraction of copper increases as energy bandgap decreases and tunable energy bandgap of this quantum dot material is inversely proportional to the wavelength.

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