Ab-initio study the electronic structure of InXGa1-XP nanocrystals
Other Title(s)
دراسة التركيب الإلكتروني لبلورات الانديوم كاليوم فوسفايد النانوية باستعمال صياغة المبادئ الأساسية
Dissertant
Thesis advisor
University
University of Baghdad
Faculty
College of Science
Department
Department of Physics
University Country
Iraq
Degree
Ph.D.
Degree Date
2013
English Abstract
Ab- initio Density functional theory (Ab-initio-DFT) at the generalized-gradient approximation (GGA) level with STO-3G basis set coupled with large unit cell method is used in the present work to determine the electronic structure for InXGa1-XP nanocrystals.
Nanocrystals structure is divided into two parts core and surface.
The core part for sizes (8, 16, 54, 64 and 128) and concentration for (x=0, 0.25, 0.5, 0.75 and 1) calculation with 3D periodic boundary condition (PBC), while the surface part include only (8 atoms) for concentration (x=0, 1)with 2D PBC calculation were used to simulate oxygenated (001)-(1x1) surface.
Two kinds of cells are investigated; Bravais cubic cell multiples and primitive parallelepiped cell multiples.
Gaussain 03 programs are prepared to perform computations using Fortran as a programming language.
Position and properties of atoms which compose these crystals are entered as input data.
The final modified LUC-DFT equations are embodied in these computer routines and solved by iterative methods (self consistent field method (SCF)).
Results show that shape effects are strong compared with other previously investigated semiconductor elements and compounds which are attributed to different atomic electronic properties.
Many properties fluctuate indefinitely while other properties converge to definite values.
Abstract XIV Quantities such as ionicity, cohesive energy and density of states reach definite values.
However, energy gap, conduction band, electron affinity ionization potential fluctuates indefinitely depending on the shape and surfaces of the nanocrystal.
Results for zinc blende III-V InP and GaP core part for (8 atoms) show the value of energy gap are equal to (1.29 , 1.64)eV respectively, while the energy gap for InP-O and GaP-O at the same core part are equal to (0.33, 0.21)eV respectively.
The lattice constant for InP-O and GaP-O was about (0.53, 0.513)nm respectively, which slightly smaller than for the core part is equal to (0.57, 0.52)nm respectively.
The valence and conduction bands width is wider and lower density of states to the surface part compare with the core part for InP and GaP.
The energy gap for alloying composition InXGa1-XP is equal to (1.41 eV) its between that for InP and GaP when x=0.5, while when x=0.75 and 0.25 the energy gap around to ~1eV.
However, energy gap, conduction band, highest occupied orbital, lowest unoccupied orbital fluctuates indefinitely depending on the shape of the nanocrystal.
While the total energy and cohesive energy are proportional linear with the number of core for all concentration .
Main Subjects
No. of Pages
178
Table of Contents
Table of contents.
Abstract.
Abstract in Arabic.
Chapter One : Introduction.
Chapter Two : Theory part.
Chapter Three : Results and discussions.
Chapter Four : Conclusions and suggestions.
References.
American Psychological Association (APA)
Abd al-Rahim, Dhikri Qasim. (2013). Ab-initio study the electronic structure of InXGa1-XP nanocrystals. (Master's theses Theses and Dissertations Master). University of Baghdad, Iraq
https://search.emarefa.net/detail/BIM-608097
Modern Language Association (MLA)
Abd al-Rahim, Dhikri Qasim. Ab-initio study the electronic structure of InXGa1-XP nanocrystals. (Master's theses Theses and Dissertations Master). University of Baghdad. (2013).
https://search.emarefa.net/detail/BIM-608097
American Medical Association (AMA)
Abd al-Rahim, Dhikri Qasim. (2013). Ab-initio study the electronic structure of InXGa1-XP nanocrystals. (Master's theses Theses and Dissertations Master). University of Baghdad, Iraq
https://search.emarefa.net/detail/BIM-608097
Language
English
Data Type
Arab Theses
Record ID
BIM-608097
