scholarly journals First-Principles Calculations on Atomic and Electronic Properties of Ge/4H-SiC Heterojunction

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Bei Xu ◽  
Changjun Zhu ◽  
Xiaomin He ◽  
Yuan Zang ◽  
Shenghuang Lin ◽  
...  
Keyword(s):  
Charge Density ◽  
Electronic Properties ◽  
Density Of States ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculation ◽  
Partial Density ◽  
Total Charge ◽  
Relaxation Energy ◽  
Total Charge Density

First-principles calculation is employed to investigate atomic and electronic properties of Ge/SiC heterojunction with different Ge orientations. Based on the density functional theory, the work of adhesion, relaxation energy, density of states, and total charge density are calculated. It is shown that Ge(110)/4H-SiC(0001) heterointerface possesses higher adhesion energy than that of Ge(111)/4H-SiC(0001) interface, and hence Ge/4H-SiC(0001) heterojunction with Ge[110] crystalline orientation exhibits more stable characteristics. The relaxation energy of Ge(110)/4H-SiC(0001) heterojunction interface is lower than that of Ge(111)/4H-SiC(0001) interface, indicating that Ge(110)/4H-SiC(0001) interface is easier to form at relative low temperature. The interfacial bonding is analysed using partial density of states and total charge density distribution, and the results show that the bonding is contributed by the Ge-Si bonding.

First-principles study on the structural, elastic and electronic properties of Ti4N3 and Ti6N5 under high pressure

2017 ◽  
Vol 31 (36) ◽  
pp. 1750349 ◽  
Author(s):  
Ruike Yang ◽  
Bao Chai ◽  
Chuanshuai Zhu ◽  
Qun Wei ◽  
Zheng Du
Keyword(s):  
Electronic Properties ◽  
Young’S Modulus ◽  
Density Of States ◽  
First Principles ◽  
Density Functional ◽  
Young's Modulus ◽  
Ambient Pressure ◽  
Pressure Rise ◽  
Partial Density ◽  
Total Density

The structural, elastic and electronic properties of Ti4N3 and Ti6N5 have been systematically studied by first-principles calculations based on density functional theory (DFT) with generalized gradient approximation (GGA) and local density approximation (LDA). Basic physical properties for Ti4N3 and Ti6N5, such as the lattice constants, the bulk modulus, shear modulus, and elastic constants are calculated. The results show that Ti4N3 and Ti6N5 are mechanically stable under ambient pressure. The phonon dispersion spectra are researched throughout the Brillouin zone via the linear response approach as implemented in the CASTEP code, which indicate the optimized structures are stable dynamically. The Young’s modulus E and Poisson’s ratios [Formula: see text] are also determined within the framework of the Voigt–Reuss–Hill approximation. The analyses show that Ti4N3 is more ductile than Ti6N5 at the same pressure and ductility increases as the pressure increases. Moreover, the anisotropies of the Ti4N3 and Ti6N5 are discussed by the Young’s modulus at different directions, and the results indicate that the anisotropy of the two Ti–N compounds is obvious. The total density of states (TDOS) and partial density of states (PDOS) show that the TDOS of TiN, Ti4N3 and Ti6N5 originate mainly from Ti “d” and N “p” states. The results show that Ti4N3 and Ti6N5 present semimetal character. Pressure makes the level range of DOS significantly extended, for TiN, Ti4N3 and Ti6N5. The TDOS decreases with the pressure rise, at Fermi level.

First-Principles Study on Energy Property and Stability of Y3Al5O12 Crystal

2013 ◽  
Vol 634-638 ◽  
pp. 2531-2536
Author(s):  
Qing Gong Song ◽  
Hui Zhao ◽  
Yi Fei Chen ◽  
Jian Hai Kang ◽  
Yan Rui Guo
Keyword(s):  
Charge Density ◽  
First Principles ◽  
First Principles Calculation ◽  
Mulliken Charge ◽  
Total Charge ◽  
Generalized Gradient ◽  
Contour Maps ◽  
Total Charge Density ◽  
Pseudo Potential ◽  
Energy Property

The geometrical structure of Y3Al5O12 (YAG) crystal was optimized by using first-principles calculation scheme, i.e. generalized gradient approximation (GGA) with the PW91 exchange correlation potential and “on the fly” pseudo-potential (OTFPP). The obtained lattice parameters are in good accordance with experimental results reported in the literature. This confirms the validity of the present GGA-OTFPP scheme. The total energy, populations, and contour maps of total charge density of YAG system were calculated with the same scheme. The derived formation energy (-2.396eV) indicate the good stability of the structure. The obtained Mulliken charge populations of atoms, overlap populations, as well as contour maps of total charge density congruously show that YAG crystal is a mixed bond material with stronger ion bond and weaker covalence bond.

scholarly journals Structural and Electronic Properties of Orthorhombic Phase Bi2Se3 Based On First-Principles Study

2019 ◽  
Vol 16 (2) ◽  
pp. 77 ◽  
Author(s):  
Muhammad Zamir Mohyedin ◽  
Afiq Radzwan ◽  
Mohammad Fariz Mohamad Taib ◽  
Rosnah Zakaria ◽  
Nor Kartini Jaafar ◽  
...  
Keyword(s):  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Computer Code ◽  
First Principles Calculation ◽  
Generalized Gradient ◽  
Exchange Correlation ◽  
Percentage Difference ◽  
Structural And Electronic Properties

Bi2Se3 is one of the promising materials in thermoelectric devices and very useful out of environmental concern due to its efficiency to perform at room temperature. Based on the first-principles calculation of density functional theory (DFT) by using CASTEP computer code, structural and electronic properties of Bi2Se3 were investigated. The calculation is conducted within the exchange-correlation of local density approximation (LDA) and generalized gradient approximation within the revision of Perdew-Burke-Ernzerhof (GGA-PBE) functional. It was found that the results are consistent with previous works of theoretical study with small percentage difference. LDA exchange-correlation functional method is more accurate and have a better agreement than GGA-PBE to describe the structural properties of Bi2Se3 which consist of lattice parameters. LDA functional also shown more accurate electronic structure of Bi2Se3 that consist of band structure and density of states (DOS) which consistent with most previous theoretical works with small percentage difference. This study proves the reliability of CASTEP computer code and show LDA exchange-correlation functional is more accurate in describing the nature of Bi2Se3 compared to the other functionals.

scholarly journals First-Principles Calculation of Conductivity of Ce-C Codoped SnO2 Contacts

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Can Ding ◽  
Zhenjiang Gao ◽  
Xing Hu ◽  
Zhao Yuan
Keyword(s):  
Charge Density ◽  
Lattice Constant ◽  
First Principles ◽  
Density Functional ◽  
Energy Levels ◽  
Circuit Breaker ◽  
Enthalpy Change ◽  
First Principles Calculation ◽  
Contact Material ◽  
Electronic Density

The contact is the core element of the vacuum interrupter of the mechanical DC circuit breaker. The electrical conductivity and welding resistance of the material directly affect its stability and reliability. AgSnO2 contact material has low resistivity, welding resistance, and so on. This material occupies an important position of the circuit breaker contact material. This research is based on the first-principles analysis method of density functional theory. The article calculated the lattice constant, enthalpy change, energy band, electronic density of state, charge density distribution, population, and conductivity of Ce, C single-doped, and Ce-C codoped SnO2 systems. The results show that Ce, C single doping, and Ce-C codoping all increase the cell volume and lattice constant. When the elements are codoped, the enthalpy change is the largest, and the thermal stability is the best. It has the smallest bandgap, the most impurity energy levels, and the least energy required for electronic transitions. The 4f orbital electrons of the Ce atom and the 2p orbital electrons of C are the sources of impurity energy near the Fermi level. When the elements are codoped, more impurity energy levels are generated at the bottom of the conduction band and the top of the valence band. Its bandgap is reduced so conductivity is improved. From the charge density and population analysis, the number of free electrons of Ce atoms and C atoms is redistributed after codoping. It forms a Ce-C covalent bond to further increase the degree of commonality of electrons and enhance the metallicity. The conductivity analysis shows that both single-doped and codoped conductivity have been improved. When the elements are codoped, the conductivity is the largest, and the conductivity is the best.

Electronic Properties of Calcium and Zirconium Co-Doped BaTiO3

2020 ◽  
Vol 1010 ◽  
pp. 308-313
Author(s):  
Akeem Adekunle Adewale ◽  
Abdullah Chik ◽  
Ruhiyuddin Mohd Zaki
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Of States ◽  
Energy Band ◽  
Density Functional ◽  
Partial Density ◽  
Total Density ◽  
Energy Band Gap ◽  
Wide Energy ◽  
Direct Band

Barium titanate (BaTiO3) is a perovskite based oxides with many potential application in electronic devices. From experimental report BaTiO3 has wide energy band gap of about 3.4 eV which by doped with Ca and Zr at A- and B- sites respectively can enhance their piezoelectric properties. Using first principles method within the density functional theory (DFT) as implement in Quantum Espresso (QE) with the plane wave pseudo potential function, the influence of the Ca and Zr doping in BaTiO3 are studied via electronic properties: band structure, total density of states (TDOS) and partial density of states (PDOS). The energy band gap calculated was underestimation which is similar to other DFT work. Two direct band gap where observed in Ba0.875Ca0.125Ti0.875Zr0.125O3 sample at Γ- Γ (2.31 eV) and X- X (2.35 eV) symmetry point.

H2 ADSORPTION ON LiB (001) SURFACE: A FIRST PRINCIPLES CALCULATION

2012 ◽  
Vol 11 (04) ◽  
pp. 781-790 ◽  
Author(s):  
WEI-BIN ZHANG ◽  
WEI-DONG WU ◽  
XIN-LU CHENG ◽  
XUE-MIN WANG ◽  
HAI-PING WANG ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Dft Method ◽  
First Principles Calculation ◽  
Partial Density ◽  
Functional Theory ◽  
H2 Adsorption ◽  
Partially Saturated ◽  
Before And After ◽  
Density Band

The adsorption behavior of H2 on the LiB (001) surface was investigated with density functional theory (DFT) method. It was found that the site of H2 adsorbed on the Li-B bridge II was easier than the other four sites ( Li top, B top, hollow vertical and Li-B bridge I). H2 adsorbed on the Li-B bridge II site was a strong chemical adsorption. The adsorption energy was 2.190 eV, and the H , B atoms exhibited covalent characteristics, the H – H atoms have a little interaction, and the H2 was 0.331 Å below the surface of Li-B bridge II. The charge density, band structure, totals and partial density of states were calculated utilizing the first principle method. These calculations showed that the H interacted with the surface atoms, and partially saturated the dangling bonds with the surface atoms. The interaction between H and the surface atoms were mainly attributed to the H 1 s, B 2 s and B 2 p states. The calculated band gap was 0.075 eV and 0.199 eV before and after adsorption.

Electronic Structure and Ground State Properties of A4[Ag4O4] (A=Na, K and Rb): A First-Principles Study

2013 ◽  
Vol 665 ◽  
pp. 43-48
Author(s):  
Rajagopalan Umamaheswari ◽  
M. Yogeswari ◽  
G. Kalpana
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Ground State ◽  
First Principles ◽  
Density Functional ◽  
Electronic Band Structure ◽  
First Principles Calculation ◽  
Partial Density ◽  
Electronic Band ◽  
Ground State Properties

The first-principles calculation within density functional theory is used to study in detail the electronic structure and ground state properties of alkali-metal oxoargenates A4[Ag4O4] (A= Na, K and Rb). The total energies calculated within the atomic sphere approximation (ASA) were used to determine the ground state properties such as equilibrium lattice parameter, c/a ratio, bulk modulus and cohesive energy. The theoretically calculated equilibrium lattice constants values are in well agreement with the available experimental values. The electronic band structures, total and partial density of states are calculated. The result of electronic band structure shows that the KAgO and RbAgO are direct band gap semiconductors with their gap lying between the Γ-Γ points, whereas NaAgO is found to be an indirect band gap semiconductor with its gap lying between Z-Γ points.

scholarly journals First-principles insights on mechanical and electronic properties of TiX (X=C,N) in β-Si3N4 based ceramics

2016 ◽  
Vol 10 (3) ◽  
pp. 153-160 ◽  
Author(s):  
Harsha Shanmugakumar ◽  
Nagarajan Veerappan ◽  
Chandiramouli Ramanathan
Keyword(s):  
Density Functional Theory ◽  
Shear Modulus ◽  
Electronic Properties ◽  
Density Of States ◽  
First Principles ◽  
Density Functional ◽  
Si3n4 Ceramic ◽  
Functional Theory ◽  
Clear Insight ◽  
Si3n4 Ceramics

The mechanical and electronic properties of ?-Si3N4, TiC-Si3N4 and TiN-Si3N4 ceramics are investigated using density functional theory implemented with GGA/PBE functional. The pristine ?-Si3N4 exhibits fracture for a strain of 10%. However, TiC-Si3N4 and TiN-Si3N4 ceramics exhibits fracture for a strain of 20%. The Young?s modulus, shear modulus and bulk modulus of the pristine ?-Si3N4, TiC-Si3N4 and TiN-Si3N4 ceramics are reported. TiN-Si3N4 ceramic is found to be the least compressible and hard. The band gap is found to decrease for TiC-Si3N4 and TiN-Si3N4 ceramics comparedwith the pristine ?-Si3N4. The density of states spectrumshows more peak maxima for TiC-Si3N4 and TiN-Si3N4 ceramics rather than ?-Si3N4. The finding of the present work gives a clear insight on the mechanical and electronic properties of ?-Si3N4, TiC-Si3N4 and TiN-Si3N4 ceramics at the atomistic level.

Electronic properties of two-dimensional ZnO atomically sheet on Cu substrate: a first-principles study

2014 ◽  
Vol 28 (26) ◽  
pp. 1450204 ◽  
Author(s):  
Fayyaz Hussain ◽  
M. Imran ◽  
Y. Q. Cai ◽  
Hafeez Ullah ◽  
Abdul Shakoor ◽  
...  
Keyword(s):  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Schottky Contact ◽  
First Principles Calculation ◽  
Two Dimensional ◽  
Cu Substrate ◽  
Conduction Bands ◽  
Structural And Electronic Properties ◽  
Potential Applications

Bulk ZnO has traditionally been regarded as multifunctional materials for energy and optoelectronics applications. Recently, exploring this material at the nanoscale has been reported and seeking a proper substrate is highly desired. In this work, the structural and electronic properties of graphene like ZnO two-dimensional (2D) monolayer are investigated by first principles calculation based on density functional theory. The alignment of the valence and conduction bands of ZnO with the state of Cu substrate is analyzed. Particularly the attention has been focused on the establishment of a Schottky contact and interfacial charge transfer between the 2D ZnO monolayer and Cu substrate. It is predicted that the electronic charges are accumulated on the Zn and O atoms due to d–d hybridization between Cu and Zn . Our study reveals that the significant interaction between the ZnO and Cu can greatly modify the electronic properties of the ZnO and suggests potential applications in nanoelectronic devices.

The structural, electronic and optical properties of Au–ZnO interface structure from the first-principles calculation

2018 ◽  
Vol 32 (07) ◽  
pp. 1850107 ◽  
Author(s):  
Jin-Rong Huo ◽  
Lu Li ◽  
Hai-Xia Cheng ◽  
Xiao-Xu Wang ◽  
Guo-Hua Zhang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Density Of States ◽  
First Principles ◽  
Density Functional ◽  
Interface Structure ◽  
First Principles Calculation ◽  
Total Density ◽  
Electronic Density ◽  
Electronic And Optical Properties ◽  
Interface Structures

The interface structure, electronic and optical properties of Au–ZnO are studied using the first-principles calculation based on density functional theory (DFT). Given the interfacial distance, bonding configurations and terminated surface, we built the optimal interface structure and calculated the electronic and optical properties of the interface. The total density of states, partial electronic density of states, electric charge density and atomic populations (Mulliken) are also displayed. The results show that the electrons converge at O atoms at the interface, leading to a stronger binding of interfaces and thereby affecting the optical properties of interface structures. In addition, we present the binding energies of different interface structures. When the interface structure of Au–ZnO gets changed, furthermore, varying optical properties are exhibited.

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