scholarly journals Influence of quantum dot shape on energy spectra of three-dimensional quantum dots superlattices

2020 ◽  
Vol 21 (4) ◽  
pp. 584-590
Author(s):  
I.V. Bilynskyi ◽  
R.Ya. Leshko ◽  
H.O. Bandura
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Three Dimensional ◽  
Energy Spectra ◽  
Band Spectrum ◽  
High Symmetry ◽  
Different Shapes

The band spectrum of quantum dots superlattices of different shapes at points of high symmetry is determined. Cubic, cylindrical and spherical quantum dots are considered. The width of the minizone is calculated. The dependences of the minizones on the geometric dimensions of quantum dots and their concentration are established.

scholarly journals Simple and Multi-layered Quantum dot in various structures

2018 ◽  
Vol 2 (4) ◽  
Author(s):  
Manu Mitra
Keyword(s):  
Quantum Dots ◽  
Wave Function ◽  
Optical Properties ◽  
Quantum Dot ◽  
Three Dimensional ◽  
Polarized Light ◽  
High Peak ◽  
Different Color ◽  
Incoming Light ◽  
Dimensional Wave

Abstract: Quantum dots have interesting optical properties. They absorb incoming light of one color and emit out light of a completely different color. This research paper discloses eigen states of a simple and multilayer quantum dot in various structures for cuboid, cylinder, dome, cone, and pyramid, and its three-dimensional wave function, energy states, light and dark transitions (X-polarized), light and dark transitions (Y-polarized), light and dark transitions (Zpolarized), light and dark transitions (phi = 0 and theta= 45), absorption (phi = 0 and theta = 45), absorption sweep of angle theta, and integrated absorption are plotted and the observations of high peak values are noted and documented.

Investigation of the Electron Energy Spectrum in a Three Dimensional Regimented Tetragonal Quantum Dot Superlattice

2001 ◽  
Vol 677 ◽  
Author(s):  
Olga L. Lazarenkova ◽  
Alexander A. Balandin
Keyword(s):  
Quantum Dots ◽  
Energy Spectrum ◽  
Quantum Dot ◽  
Electron Energy ◽  
Electronic Band Structure ◽  
Three Dimensional ◽  
Electron Energy Spectrum ◽  
Real Crystal ◽  
Electronic Band ◽  
Gaas Quantum Dot

ABSTRACTWe analyze the electron energy spectrum in three-dimensional regimented arrays of semiconductor quantum dots. The coupling among quantum dots results in formation of three- dimensional electron mini-bands. Changing the size of quantum dots, inter-dot distance, barrier height and regimentation, one can control the electronic band structure of this quantum dot superlattice, which can also be referred to as quantum dot crystal due to its structure and energy spectrum that resemble those of a real crystal. Results of computer simulations carried out for a tetragonal InAs/GaAs quantum dot superlattice show that the electron density of states, effective mass tensor and other properties are different from those of bulk and conventional quantum well superlattices.

Kinematical Analysis of the Evolution of Reflection High Energy Electron Diffraction Patterns of Quantum Dot Heterostructures: Correlation with Strain and Anisotropy

2006 ◽  
Vol 924 ◽  
Author(s):  
Andrea Feltrin ◽  
Alexandre Freundlich
Keyword(s):  
Quantum Dots ◽  
Electron Diffraction ◽  
Quantum Dot ◽  
Three Dimensional ◽  
High Energy ◽  
Image Features ◽  
Energy Electron ◽  
Clear Correlation ◽  
High Energy Electron ◽  
Strain Anisotropy

ABSTRACTThe strain distributions and of reflection high energy electron diffraction (RHEED) patterns of uncapped pyramidal shape InAs Stranski-Krastanov quantum dots fabricated on GaAs(001) substrate are investigated theoretically. The three dimensional strain anisotropy is computed with an atomistic elasticity approach, using inter-atomic Keating potentials and the strain energy is minimized using the conjugate gradient numerical method. RHEED images are predicted in the framework of the kinematical theory, by taking into account the refraction of the electron beam at the quantum dot/vacuum interface. Clear correlation between RHEED image features and quantum dot structural properties is established. The study stresses the potential of RHEED for future experimental real-time (during growth) detections and deciphering of strain anisotropies in quantum dots.

Energy Spectra of the Low-Lying State in N-Layer Quantum Dots

2013 ◽  
Vol 483 ◽  
pp. 170-173
Author(s):  
An Mei Wang
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
Angular Momentum ◽  
External Magnetic Field ◽  
Quantum Dot ◽  
Applied Magnetic Field ◽  
Ground State ◽  
Weak Coupling ◽  
State Energy ◽  
Energy Spectra

A method is proposed to exactly diagonalize the Hamiltonian of a N-layer quantum dot containing a single electron in each dot in arbitrary magnetic fields. the energy spectra of the dot are calculated as a function of the applied magnetic field. We find disco-ntinuous ground-state energy transitions induced by an external magnetic field in the case of strong coupling. However, in the case of weak coupling, such a transition does not occur and the angular momentum remains zero.

Size and Piezoelectric Effects on Optical Properties of Self-Assembled InGaAs/GaAs Quantum Dots

2006 ◽  
Author(s):  
M. K. Kuo ◽  
T. R. Lin ◽  
K. B. Hong
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Quantum Dot ◽  
Optical Transition ◽  
Energy Levels ◽  
Three Dimensional ◽  
Dinger Equation ◽  
Element Analysis ◽  
Piezoelectric Effects ◽  
Self Assembled

Size effects on optical properties of self-assembled quantum dots are analyzed based on the theories of linear elasticity and of strain-dependent k-p with the aid of finite element analysis. The quantum dot is made of InGaAs with truncated pyramidal shape on GaAs substrate. The three-dimensional steady-state effective-mass Schro¨dinger equation is adopted to find confined energy levels as well as wave functions both for electrons and holes of the quantum-dot nanostructures. Strain-induced as well as piezoelectric effects are taken into account in the carrier confinement potential of Schro¨dinger equation. The optical transition energies of quantum dots, computed from confined energy levels for electrons and holes, are significantly different for several quantum dots with distinct sizes. It is found that for QDs with the the larger the volume of QD is, the smaller the values of the optical transition energy. Piezoelectric effect, on the other hand, splits the p-like degeneracy for the electron first excited state about 1~7 meV, and leads to anisotropy on the wave function.

scholarly journals Production of three-dimensional quantum dot lattice of Ge/Si core–shell quantum dots and Si/Ge layers in an alumina glass matrix

2015 ◽  
Vol 26 (6) ◽  
pp. 065602 ◽  
Author(s):  
M Buljan ◽  
N Radić ◽  
J Sancho-Paramon ◽  
V Janicki ◽  
J Grenzer ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Glass Matrix ◽  
Three Dimensional ◽  
Core Shell

Application of Finite Difference Method in Modeling Quantum Dot Superlattice Silicon Tandem Solar Cell

2014 ◽  
Vol 898 ◽  
pp. 249-252 ◽  
Author(s):  
Jie Huang ◽  
Jian Liang Jiang ◽  
Abdelkader Sabeur
Keyword(s):  
Quantum Dots ◽  
Solar Cell ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Quantum Dot ◽  
Difference Method ◽  
Matrix Material ◽  
Three Dimensional ◽  
Tandem Solar Cell ◽  
The Matrix

In this paper we propose an effective method to model quantum dot superlattice silicon tandem solar cell. The Schrödinger equation is solved through finite difference method (FDM) to calculate energy band of three-dimensional silicon quantum dots embedded in the matrix of SiO2 and Si3N4.We simulate the quantum dot superlattice as regularly spaced array of equally sized cubic dots in respective matrix. For simplicity, we consider only one period of the structure in calculation. From the result, the effects of matrix material, dot size and inter-dot distance on the bandgap are obtained.

Growth of a three-dimensional anisotropic lattice of Ge quantum dots in an amorphous alumina matrix

2013 ◽  
Vol 46 (3) ◽  
pp. 709-715 ◽  
Author(s):  
Maja Buljan ◽  
Olga Roshchupkina ◽  
Ana Šantić ◽  
Václav Holý ◽  
Carsten Baehtz ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Self Assembly ◽  
Three Dimensional ◽  
Sample Surface ◽  
Material Surface ◽  
Simple Method ◽  
Sputtering Deposition ◽  
Anisotropic Lattice ◽  
Ge Quantum Dots

Simple processes for the preparation of semiconductor quantum dot lattices embedded in dielectric amorphous matrices play an important role in various nanotechnology applications. Of particular interest are quantum dot lattices with properties that differ significantly in different directions parallel to the material surface. Here, a simple method is demonstrated for the fabrication of an anisotropic lattice of Ge quantum dots in an amorphous Al2O3matrix by a self-assembly process. A specific deposition geometry with an oblique incidence of the Ge and Al2O3adparticles was used during magnetron sputtering deposition to achieve the desired anisotropy. The observed Ge quantum dot ordering is explained by a combination of directional diffusion of adparticles from the Ge and Al2O3targets and a shadowing process which occurs during deposition as a result of the specific surface morphology. The prepared material shows a strong anisotropy of the electrical conductivity in different directions parallel to the sample surface.

scholarly journals Strain Distributions in Group IV and III-V Semiconductor Quantum Dots

2013 ◽  
Vol 7 ◽  
pp. 36-48
Author(s):  
K.A.I.L. Wijewardena Gamalath ◽  
M.A.I.P. Fernando
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Lattice Mismatch ◽  
Three Dimensional ◽  
Group Iv ◽  
Group Iii ◽  
Elastic Tensor ◽  
Hydrostatic Strain ◽  
Anisotropic Elastic ◽  
Group Iii V Semiconductor

A theoretical model was developed using Green’s function with an anisotropic elastic tensor to study the strain distribution in and around three dimensional semiconductor pyramidal quantum dots formed from group IV and III-V material systems namely, Ge on Si, InAs on GaAs and InP on AlP. A larger positive strain in normal direction which tends to zero beyond 6nm was observed for all three types while the strains parallel to the substrate were negative. For all the three types of quantum dots hydrostatic strain and biaxial strain along x and z directions were not linear but described a curve with a maximum positive value near the base of the quantum dot. The hydrostatic strain in x-direction is mostly confined within the quantum dot and practically goes to zero outside the edges of the quantum dot. For all the three types, the maximum hydrostatic and biaxial strains occur in x-direction around -1nm and around 2nm in z-direction. The negative strain in x-direction although realtively weak penetrate more deeper to the substrate than hydrostatic strain.The group IV substrate gave larger hydrostatic and biaxial strains than the group III-V semiconductor combinations and InAs /GaAs was the most stable. The results indicated that the movements of atoms due to the lattice mismatch were strong for group III-V.

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