Ab-initio Calculation method of electronic structure of InXGa1-XAs nanocrystal

العناوين الأخرى

التركيب الإلكتروني لبلورة (InxGa1-xAs)‎ النانوية بطريقة الحسابات الأساسية (Ab-inito)‎

مقدم أطروحة جامعية

Bayraqdar, Akram Hashim Taha

مشرف أطروحة جامعية

Husayn, Muhammad Taqi

الجامعة

جامعة بغداد

الكلية

كلية العلوم

القسم الأكاديمي

قسم الفيزياء

دولة الجامعة

العراق

الدرجة العلمية

دكتوراه

تاريخ الدرجة العلمية

2013

الملخص الإنجليزي

Ab-initio density functional theory (DFT) at the generalized gradient approximation (GGA) level coupled with large unit cell (LUC) method with STO-3G basis sets have been used to determine and investigate the electronic properties of Indium Gallium Arsenide (InxGa1-xAs) nanocrystals with different core part size (8, 16, 54, 64) and concentrations (x=0.

, 0.25, 0.50 and 1.0), using 3D periodic boundary condition (PBC).

Two kinds of cells were investigated; Bravais cubic cell multiples and primitive parallelpiped cell multiples.

Gaussian 03 programs were prepared to perform computation using Fortran as programming language.

The atoms positions and their properties for above crystals have been used as input data.

The final modified LUC-Ab-initio-DFT equations are embodied in the computer and solved by iterative self consistent field (SCF) methods.

The electronic properties such as ionicity, cohesive energy and density of states (which reaches definite values) have been calculated, in addition to that the energy gap, conduction and valence band, electron affinity, ionization potential have been calculated taking into account the fluctuates in definitely depending on the shape.

The obtained results for zinc-blende III-V GaAs core part shows it has dimensions around (1.56-2.04) nm.

The values of energy gap in the The obtained results for zinc–blende III-V InAs core part shows, it has dimensions in the range (1.71-2.32) nm while the values of energy gap in the range of (2.41-2.57) eV corresponding to the lattice constant between XII (0.57-0.58) nm for different core size atoms (8, 16, 54, 64).

The size and alloy compound for InxGa1-xAs is varied so that it can be tuned to the required applications.

Zinc-blende InxGa1-xAs nanocrystals which show dimensions around (1.59-2.27) nm, while, the small values of energy gap in the range of (1.02-2.00) eV and increasing the ratio of In in the InxGa1-xAs may be attribute to the alloying composition.

While the total energy and cohesive energy are inversely is found to be proportional with the number of core for all concentrations (0, 0.25, 0.50, 0.75, 1.0).

التخصصات الرئيسية

الفيزياء

عدد الصفحات

101

قائمة المحتويات

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-607665