Systematic first principles calculations of the effects of stacking faults defects on the 4H-SiC band structure

2010 ◽  
Vol 1246 ◽  
Author(s):  
Massimo Camarda ◽  
pietro delugas ◽  
Andrea Canino ◽  
Andrea Severino ◽  
nicolo piluso ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Stacking Faults ◽  
Perfect Crystal ◽  
First Principles Calculations ◽  
Electronic Band ◽  
Functional Theory ◽  
Experimental Findings ◽  
Electronic Band Structures ◽  
Formation Energies

AbstractShockley-type Stacking faults (SSF) in hexagonal Silicon Carbide polytypes have received considerable attention in recent years since it has been found that these defects are responsible for the degradation of forward I-V characteristics in p-i-n diodes. In order to extend the knowledge on these kind of defects and theoretically support experimental findings (specifically, photoluminescence spectral analysis), we have determined the Kohn-Sham electronic band structures, along the closed path Γ-M-K-Γ, using density functional theory. We have also determined the energies of the SSFs with respect to the perfect crystal finding that the (35) and (44) SSFs have unexpectedly low formation energies, for this reason we could expect these two defects to be easily generated/expanded either during the growth or post-growth process steps.

Systematic First Principles Calculations of the Effects of Stacking Fault Defects on the 4H-SiC Band Structure

2010 ◽  
Vol 645-648 ◽  
pp. 283-286 ◽  
Author(s):  
Massimo Camarda ◽  
Pietro Delugas ◽  
Andrea Canino ◽  
Andrea Severino ◽  
Nicolò Piluso ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Stacking Faults ◽  
Perfect Crystal ◽  
First Principles Calculations ◽  
Electronic Band ◽  
Functional Theory ◽  
Experimental Findings ◽  
Electronic Band Structures ◽  
Formation Energies

Shockley-type Stacking faults (SSF) in hexagonal Silicon Carbide polytypes have received considerable attention in recent years since it has been found that these defects are responsible for the degradation of forward I-V characteristics in p-i-n diodes. In order to extend the knowledge on these kind of defects and theoretically support experimental findings (specifically, photoluminescence spectral analysis), we have determined the Kohn-Sham electronic band structures, along the closed path Γ-M-K-Γ, using density functional theory. We have also determined the energies of the SSFs with respect to the perfect crystal finding that the (35) and (44) SSFs have unexpectedly low formation energies, for this reason we could expect these two defects to be easily generated/expanded either during the growth or post-growth process steps.

Electronic band structures of Ge1−xSnx semiconductors: A first-principles density functional theory study

2013 ◽  
Vol 113 (6) ◽  
pp. 063517 ◽  
Author(s):  
Ming-Hsien Lee ◽  
Po-Liang Liu ◽  
Yung-An Hong ◽  
Yen-Ting Chou ◽  
Jia-Yang Hong ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Density Functional Theory Study ◽  
Band Structures ◽  
Electronic Band ◽  
Functional Theory ◽  
Electronic Band Structures

Phases Stability of Ni-Mn-Ga Alloys Studied by Ab Initio Calculations

2014 ◽  
Vol 783-786 ◽  
pp. 1646-1651
Author(s):  
N. Xu ◽  
J.M. Raulot ◽  
Z.B. Li ◽  
Y.D. Zhang ◽  
J. Bai ◽  
...  
Keyword(s):  
Ab Initio ◽  
First Principles ◽  
Density Functional ◽  
Stable Phase ◽  
First Principles Calculations ◽  
Atomic Position ◽  
Functional Theory ◽  
Ab Initio Simulation ◽  
Formation Energies ◽  
Simulation Package

The phase stabilities and magnetic properties in Ni-Mn-Ga alloys are systematically investigated by means of the first-principles calculations within the framework of density functional theory using the vienna ab initio simulation package. The calculated formation energies show that the tetragonal NM martensite is the most stable phase compared with the cubic austenite and the modulated monoclinic martensite for stoichiometric Ni2MnGa. The atomic magnetic moment keeps constant in austenite and NM martensite, whereas those of Ni and Mn in the modulated martensite oscillate according to the atomic position. Furthermore, The formation energies of the various compositions have been systematically calculated.

Investigations of Physical Properties of XTiH3 and Implications for Solid State Hydrogen Storage

2019 ◽  
Vol 74 (11) ◽  
pp. 1023-1030 ◽  
Author(s):  
Selgin AL
Keyword(s):  
Density Functional Theory ◽  
Solid State ◽  
Hydrogen Storage ◽  
Density Functional ◽  
Mechanical Stability ◽  
Mechanical Anisotropy ◽  
Electronic Band ◽  
Functional Theory ◽  
Electronic Band Structures ◽  
Formation Energies

AbstractThis study adopts density functional theory to predict and thoroughly investigate new types of perovskite compounds for solid state storage of hydrogen. CaTiH3 and MgTiH3 perovskite hydrides are chosen and investigated using density functional theory in terms of ground state properties, electronic, mechanical, and thermodynamic properties for solid state storage of hydrogen. Stability of compounds are verified by calculating formation energies. Several crucial parameters; elastic constants, bulk, Young, Shear modulus, and Cauchy pressures are computed and analysed in great detail. Mechanical stability evaluation indicated that both compounds are mechanically stable whereas MgTiH3 is ductile whilst CaTiH3 is a brittle material. In addition, mechanical anisotropy is analysed using 2D surfaces. Both compounds showed anisotropic behaviour in all directions except for linear compressibility. Electronic band structures and their corresponding density of states of compounds are obtained. The results indicate that both compounds have metallic nature. From the results presented here, it can be predicted that MgTiH3 is a better material for hydrogen storage with a gravimetric density of ∼4.01 wt %.

REACTIVITY AND STABILITY OF OXYGEN VACANCIES ON TiO2 ANATASE (101) SURFACE: FIRST-PRINCIPLES CALCULATIONS

2011 ◽  
Vol 25 (29) ◽  
pp. 4029-4037
Author(s):  
QILI CHEN ◽  
CHAOQUN TANG ◽  
BO LI ◽  
GUANG ZHENG ◽  
KAIHUA HE
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Atomic Displacement ◽  
Oxygen Adsorption ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Tio2 Anatase ◽  
Technical Parameters ◽  
Formation Energies

In this study, density-functional theory plane-wave pseudopotential method was employed to investigate several oxygen vacancies on TiO 2 anatase (101) surface. At first, a suitable defect-free slab model has been established by analyzing the surface energies and the atomic relaxations influenced by different technical parameters. The formation energies of different kinds of oxygen vacancies in the outermost layer have also been compared as well as the atomic displacement of the defective surfaces. It was found that the presence of bridging oxygen vacancy is more energetically favored and causes larger atomic displacement than other types of surface oxygen vacancies. The reactivity of oxygen vacancies has also been tested by both molecular and dissociated oxygen adsorption. Furthermore, we discussed the configurations and the electronic properties of O 2-adsorbed surface, and found that the appearance of oxygen adsorbate-induced states in the band gap can make the surface sensitive to visible light.

Thermodynamic Stability of Hexagonal and Rhombohedral Bn at Cvd Conditions from Van der Waals Corrected First Principles Calculations

2019 ◽  
Author(s):  
Henrik Pedersen ◽  
Björn Alling ◽  
Hans Högberg ◽  
Annop Ektarawong
Keyword(s):  
Thin Films ◽  
Thermodynamic Stability ◽  
First Principles ◽  
Thermal Equilibrium ◽  
Density Functional ◽  
Van Der Waals ◽  
Chemical Vapor ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Stability

Thin films of boron nitride (BN), particularly the sp<sup>2</sup>-hybridized polytypes hexagonal BN (h-BN) and rhombohedral BN (r-BN) are interesting for several electronic applications given band gaps in the UV. They are typically deposited close to thermal equilibrium by chemical vapor deposition (CVD) at temperatures and pressures in the regions 1400-1800 K and 1000-10000 Pa, respectively. In this letter, we use van der Waals corrected density functional theory and thermodynamic stability calculations to determine the stability of r-BN and compare it to that of h-BN as well as to cubic BN and wurtzitic BN. We find that r-BN is the stable sp<sup>2</sup>-hybridized phase at CVD conditions, while h-BN is metastable. Thus, our calculations suggest that thin films of h-BN must be deposited far from thermal equilibrium.

scholarly journals Hydrogenation and oxidation enhances the thermoelectric performance of Si2BN monolayer

2021 ◽  
Author(s):  
H. R. Mahida ◽  
Deobrat Singh ◽  
Yogesh Sonvane ◽  
Sanjeev K. Gupta ◽  
P. B. Thakor ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Charge Transport ◽  
Transport Properties ◽  
First Principles ◽  
Density Functional ◽  
Thermoelectric Performance ◽  
First Principles Calculations ◽  
Functional Theory

In the present study, we have investigated the structural, electronic, and charge transport properties of pristine, hydrogenated, and oxidized Si2BN monolayers via first-principles calculations based on density functional theory (DFT).

Probing the electronic structures of Con (n = 1–5) clusters on γ-Al2O3 surfaces using first-principles calculations

2017 ◽  
Vol 19 (5) ◽  
pp. 3679-3687 ◽  
Author(s):  
Tao Yang ◽  
Masahiro Ehara
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
First Principles Calculations ◽  
Functional Theory

Using density functional theory calculations, we discussed the geometric and electronic structures and nucleation of small Co clusters on γ-Al2O3(100) and γ-Al2O3(110) surfaces.

Electronic structure of cubic BaTbO3 from first-principles pseudopotential calculations

2006 ◽  
Vol 84 (2) ◽  
pp. 115-120 ◽  
Author(s):  
G Y Gao ◽  
K L Yao ◽  
Z L Liu
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Pseudopotential Calculations ◽  
Correlation Potential ◽  
Density Contour

First-principles calculations of the electronic structure are performed for cubic BaTbO3 using the plane-wave pseudopotential method within the framework of density functional theory and using the generalized gradient approximation for the exchange-correlation potential. Our calculations show that cubic BaTbO3 is metallic, and that this metallic character is mainly governed by the Tb 4f electrons and the hybridization between the Tb 5d and O 2p states. From the analysis of the density of states, band structure, and charge density contour, we find that the chemical bonding between Tb and O is covalent while that between Ba and TbO3 is ionic. PACS Nos.: 71.15.Mb, 71.20.-b

Computational investigation of NH3 adsorption and dehydrogenation on a W-modified Fe(111) surface

2015 ◽  
Vol 17 (45) ◽  
pp. 30598-30605 ◽  
Author(s):  
Ming-Kai Hsiao ◽  
Chia-Hao Su ◽  
Ching-Yang Liu ◽  
Hui-Lung Chen
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Computational Investigation ◽  
Functional Theory ◽  
Nh3 Adsorption ◽  
Tungsten Metal

We employed monolayer tungsten metal to modify the Fe(111) surface, denoted as W@Fe(111), and calculated the adsorption and dehydrogenation behaviors of NH3 on W@Fe(111) surface via first-principles calculations based on density functional theory (DFT).

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