scholarly journals Ab Initio Study of MgTe Self-Interstitial (Mgi and Tei): A Wide Band Gap Semiconductor

2017 ◽  
Vol 16 ◽  
pp. 47-51
Author(s):  
Emmanuel Igumbor ◽  
Ezekiel Omotoso ◽  
Walter Ernst Meyer
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Defect Formation ◽  
Local Density ◽  
Wide Band ◽  
Shallow Donor ◽  
Generalized Gradient ◽  
Wide Band Gap ◽  
Functional Theory ◽  
Formation Energies

We present results of defect formation energies and charge state thermodynamic transition levels of Mg and Te interstitials in MgTe wurzite structure. We use the generalized gradient approximation and local density approximation functionals in the framework of density functional theory for all calculations. The formation energies of the Mg and Te interstitials in MgTe for both the tetrahedral and hexagonal configurations were obtained. The Mg and Te interstitials in MgTe depending on the functional, introduced transition state levels that are either donor or acceptor within the band gap of the MgTe. The Te interstitial exhibit charge states controlled metastability, negative-U and DX centre properties. The Mg interstitial acts as deep or shallow donor and there is no evidence of acceptor levels found for the Mg interstitial.

scholarly journals Ab Initio Study of MgSe Self-Interstitial (Mgi and Sei)

2015 ◽  
Vol 242 ◽  
pp. 440-446 ◽  
Author(s):  
Emmanuel Igumbor ◽  
Kingsley Obodo ◽  
Water E. Meyer
Keyword(s):  
Transition State ◽  
Density Functional ◽  
Local Density ◽  
Shallow Donor ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Interstitial Defects ◽  
Frame Work ◽  
Formation Energies

We present detailed calculations of formation and thermodynamics transition state energies of Mgiand Seiinterstitial defects in MgSe using generalized gradient approximation (GGA) and local density approximation (LDA) functional in the frame work of density functional theory (DFT). For both LDA and GGA the formation energies of Mgiand Seiare relatively low in all the configurations. The most stable Se interstitial was the tetrahedral (T) configuration having lower formation energy than the decagonal (D) configuration. TheMgiand Seidefect introduced transition state levels that had either donor or acceptor levels within the band gap. Seiacts as a donor or an acceptor and creates levels that were either deep or shallow depending on the configuration. Seiexhibit negative-U properties and show charge states metastability in the D configuration. Mgiacts as only shallow donor (+2/ + 1) in both T and D configurations, in addition we pointed out the role of Mgias electrically activating donor.

Theoretical Analysis of the DOS and Band Structural Properties of Ti1-XSnxO2 Solid Solutions

2012 ◽  
Vol 465 ◽  
pp. 33-36
Author(s):  
Zhi Dong Lin ◽  
Wen Long Song ◽  
Ju Cheng Zheng
Keyword(s):  
Band Gap ◽  
Solid Solutions ◽  
Density Functional ◽  
Wide Band ◽  
Low Energy ◽  
Low Density ◽  
First Principle ◽  
Wide Band Gap ◽  
Functional Theory ◽  
First Principle Calculations

The band structure and density of states (DOS) of Ti1-xSnxO2 solid solutions with x=0, 1/8, 1/4, 1/2 and 1 were investigated by means of the first-principle calculations based on density functional theory. The result indicated that band gap and Fermi level of TiO2-SnO2 vary continuously from those of pure TiO2 to those of Sn content increasing. In addition, the DOS moves towards low energy and the bang gap is broadened with growing value of x. The wide band gap and the low density of the states in the conduction band result in the enhancement of photoactivity in Ti1-xSnxO2.

Charged Defect Formation Energies in TiO2 Using the Supercell Approximation

2006 ◽  
Vol 45 ◽  
pp. 1-8 ◽  
Author(s):  
Jun He ◽  
Mike W. Finnis ◽  
Elizabeth C. Dickey ◽  
Susan B. Sinnott
Keyword(s):  
Point Defects ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Defect Formation ◽  
Density Functional Theory Calculations ◽  
Wide Band ◽  
Wide Band Gap ◽  
Influence Of Temperature On ◽  
Formation Energies ◽  
Positively Charged

TiO2 has been intensively studied as a wide band-gap transition metal oxide partially due to the multi-valence nature of its cation. Here, density-functional theory calculations within the supercell approximation are carried out to determine the preferred charge state of point defects in rutile TiO2. The first component of this work is to investigate the dependence of the defect formation energies on supercell size and the electrostatic Makov-Payne correction. The results show that the Makov-Payne correction improves the convergence of defect formation energies as a function of supercell size for positively charged titanium interstitials and negatively charged titanium vacancies. However, in the case of positively charged oxygen vacancies, applying the Makov-Payne correction gives the wrong sign for the defect formation energy correction. This is attributed to the shallow nature of the transition levels for this defect in TiO2. Finally, we combine the calculated defect formation energies with thermodynamic data to evaluate the influence of temperature on the relative stabilities of point defects. The results indicate that when the Makov- Payne correction is applied, a stable charge transition occurs for titanium interstitials. In addition, as the temperature increases, the dominant point defect in TiO2 changes from oxygen vacancies to titanium interstitials.

scholarly journals Investigation on the electronic structure, optical, elastic, mechanical, thermodynamic and thermoelectric properties of wide band gap semiconductor double perovskite Ba2InTaO6

RSC Advances ◽  
2019 ◽  
Vol 9 (17) ◽  
pp. 9522-9532 ◽  
Author(s):  
Sajad Ahmad Dar ◽  
Ramesh Sharma ◽  
Vipul Srivastava ◽  
Umesh Kumar Sakalle
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Band Gap ◽  
Thermoelectric Properties ◽  
Density Functional ◽  
Double Perovskite ◽  
Wide Band ◽  
Wide Band Gap ◽  
Functional Theory

In the present paper, double perovskite Ba2InTaO6 was investigated in terms of its structural, electronic, optical, elastic, mechanical, thermodynamic and thermoelectric properties using density-functional theory (DFT).

STUDY OF THE ELECTRONIC PROPERTIES OF CrO2 USING DENSITY FUNCTIONAL THEORY

2010 ◽  
Vol 24 (20) ◽  
pp. 2187-2193 ◽  
Author(s):  
M. P. GHIMIRE ◽  
SANDEEP ◽  
R. K. THAPA
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Wide Band ◽  
Local Spin Density Approximation ◽  
Wide Band Gap ◽  
Metallic Behavior ◽  
Functional Theory ◽  
Rutile Structure ◽  
Half Metallic ◽  
Direct Band

CrO 2 has a wide band gap for "down" spins and the Fermi level lies in the middle of the band gap. Calculations based on the local-spin density approximation (LSDA) has been performed to investigate the electronic and physical properties of CrO 2 in the rutile structure (P42/mnm). We considered the semicore electrons as valence electrons and found that CrO 2 appears to be half-metallic with a direct band gap of 1.8 eV in spin-down and has metallic behavior in spin-up configurations.

Theoretical Study of Native Point Defects in Aln and InN

1997 ◽  
Vol 482 ◽  
Author(s):  
C. Stampfl ◽  
Chris G. Van De Walle
Keyword(s):  
Point Defects ◽  
Density Functional ◽  
Defect Formation ◽  
Local Density ◽  
Nitrogen Vacancy ◽  
Type Material ◽  
Generalized Gradient ◽  
Native Point Defects ◽  
Zinc Blende ◽  
Formation Energies

AbstractWe have studied native point defects in AlN and InN using density-functional calculations employing both the local-density and generalized gradient approximations for the exchange-correlation functional. For both materials we find that the nitrogen vacancy acts as a compensating center in p-type material. For AIN in the zinc-blende structure, the aluminum interstitial has an equally low formation energy as the nitrogen vacancy. For n-type material the aluminum vacancy is the dominant compensating center in AlN. For n-type InN, all defect formation energies are high.

Difference in Electronic Structure between Diamond and Graphite

2012 ◽  
Vol 229-231 ◽  
pp. 74-77 ◽  
Author(s):  
Jian Hong Gong ◽  
Shu Xia Lin ◽  
Wang Li ◽  
Jun Gao
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Transition Energy ◽  
Wide Band ◽  
Direct Transition ◽  
Wide Band Gap ◽  
Covalent Bonds ◽  
Functional Theory ◽  
Structural And Electronic Properties

The structural and electronic properties of diamond and graphite were investigated by the first-principles total-energy pseudopotential method based on density functional theory. The band structure, DOS and PDOS were calculated. Results showed that diamond had a wide band gap, and its direct transition energy is 6.0 eV. But graphite’s band gap is about zero, meaning without transition energy. That explains the reasons of diamond acting as an insulator but graphite acting as a conductor. DOS and PDOS analysis results indicate both diamond and graphite are sp hybridization and p states contribute mostly to the bonding of crystal. While their covalent bonds style are different.

scholarly journals Dumbbell configuration of silicon adatom defects on silicene nanoribbons

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Huynh Anh Huy ◽  
Quoc Duy Ho ◽  
Truong Quoc Tuan ◽  
Ong Kim Le ◽  
Nguyen Le Hoai Phuong
Keyword(s):  
Magnetic Properties ◽  
Band Gap ◽  
Density Functional ◽  
Spin Moment ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Electronic And Magnetic Properties ◽  
Spin Degeneracy ◽  
Silicene Nanoribbons ◽  
Formation Energies

AbstractUsing density functional theory (DFT), we performed theoretical investigation on structural, energetic, electronic, and magnetic properties of pure armchair silicene nanoribbons with edges terminated with hydrogen atoms (ASiNRs:H), and the absorptions of silicon (Si) atom(s) on the top of ASiNRs:H. The calculated results show that Si atoms prefer to adsorb on the top site of ASiNRs:H and form the single- and/or di-adatom defects depending on the numbers. Si absorption defect(s) change electronic and magnetic properties of ASiNRs:H. Depending on the adsorption site the band gap of ASiNRs:H can be larger or smaller. The largest band gap of 1 Si atom adsorption is 0.64 eV at site 3, the adsorption of 2 Si atoms has the largest band gap of 0.44 eV at site 1-D, while the adsorption at sites5 and 1-E turn into metallic. The formation energies of Si adsorption show that adatom defects in ASiNRs:H are more preferable than pure ASiNRs:H with silicon atom(s). 1 Si adsorption prefers to be added on the top site of a Si atom and form a single-adatom defect, while Si di-adatom defect has lower formation energy than the single-adatom and the most energetically favorable adsorption is at site 1-F. Si adsorption atoms break spin-degeneracy of ASiNRs:H lead to di-adatom defect at site 1-G has the highest spin moment. Our results suggest new ways to engineer the band gap and magnetic properties silicene materials.

Density Functional Theory Approach for Muon Sites Estimation in Mn3Sn

2021 ◽  
Vol 1028 ◽  
pp. 199-203
Author(s):  
Fiqhri Heda Murdaka ◽  
Edi Suprayoga ◽  
Abdul Muizz Pradipto ◽  
Kohji Nakamura ◽  
Agustinus Agung Nugroho
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Local Density ◽  
Full Potential ◽  
Theory Approach ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Electrostatic Potential Calculation ◽  
A Site ◽  
Linearized Augmented Plane Wave

We report the estimation of muon sites inside Mn3Sn using density functional theory based on the full-potential linearized augmented plane wave (FLAPW) calculation. Our calculation shows that the Perdew–Burke–Ernzerhof (PBE) Generalized-Gradient Approximation (GGA) functional is closer to the experimental structure compared to the von Barth-Hedin Local Density Approximation (LDA)-optimized geometry. The PBE GGA is therefore subsequently used in FLAPW post-calculation for the electrostatic potential calculation to find the local minima position as a guiding strategy for estimating the muon site. Our result reveals at least two muon sites of which one is placed at the center between two Mn-Sn triangular layers (A site) and the other at the trigonal prismatic site of Sn atom (B site). The total energy of Mn3Sn system in the presence of muon at A site or B site are compared and we find that A site is a more favorable site for muon to stop.

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