First Principles Study of Boron in Amorphous Silicon

2008 ◽  
Vol 1070 ◽  
Author(s):  
Iván Santos ◽  
Wolfgang Windl ◽  
Lourdes Pelaz ◽  
Luis Alberto Marqués
Keyword(s):  
Fermi Level ◽  
Ab Initio ◽  
Amorphous Silicon ◽  
Boron Atom ◽  
Simulation Study ◽  
First Principles ◽  
Formation Energy ◽  
Chemical Potential ◽  
Md Simulations ◽  
Interstitial Space

ABSTRACTWe have carried out an ab initio simulation study of boron in amorphous silicon. In order to understand the possible structural environments of B atoms, we have studied substitutional-like (replacing one Si atom in the amorphous cell by a B atom) and interstitial-like (adding a B atom into an interstitial space) initial configurations. We have evaluated the Fermi-level dependent formation energy of the neutral and charged (±1) configurations and the chemical potential for the neutral ones. For the interstitial-like boron atom, we have find an averaged formation energy of 1.5 eV. For the substitutional case, we have found a dependence of the chemical potential on the distance to Si neighbors, which does not appear for the interstitial ones. From MD simulations, we could observe a diffusion event for an interstitial-like boron atom with a migration barrier of 0.6 eV.

scholarly journals First-Principles Assessment of the Structure and Stability of 15 Intrinsic Point Defects in Zinc-Blende Indium Arsenide

Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 48 ◽  
Author(s):  
Qing Peng ◽  
Nanjun Chen ◽  
Danhong Huang ◽  
Eric Heller ◽  
David Cardimona ◽  
...  
Keyword(s):  
Fermi Level ◽  
Charge State ◽  
Indium Arsenide ◽  
Point Defects ◽  
First Principles ◽  
Formation Energy ◽  
Fast Diffusion ◽  
Intrinsic Point Defects ◽  
Zinc Blende ◽  
Tetrahedral Sites

Point defects are inevitable, at least due to thermodynamics, and essential for engineering semiconductors. Herein, we investigate the formation and electronic structures of fifteen different kinds of intrinsic point defects of zinc blende indium arsenide (zb-InAs ) using first-principles calculations. For As-rich environment, substitutional point defects are the primary intrinsic point defects in zb-InAs until the n-type doping region with Fermi level above 0.32 eV is reached, where the dominant intrinsic point defects are changed to In vacancies. For In-rich environment, In tetrahedral interstitial has the lowest formation energy till n-type doped region with Fermi level 0.24 eV where substitutional point defects In A s take over. The dumbbell interstitials prefer < 110 > configurations. For tetrahedral interstitials, In atoms prefer 4-As tetrahedral site for both As-rich and In-rich environments until the Fermi level goes above 0.26 eV in n-type doped region, where In atoms acquire the same formation energy at both tetrahedral sites and the same charge state. This implies a fast diffusion along the t − T − t path among the tetrahedral sites for In atoms. The In vacancies V I n decrease quickly and monotonically with increasing Fermi level and has a q = − 3 e charge state at the same time. The most popular vacancy-type defect is V I n in an As-rich environment, but switches to V A s in an In-rich environment at light p-doped region when Fermi level below 0.2 eV. This study sheds light on the relative stabilities of these intrinsic point defects, their concentrations and possible diffusions, which is expected useful in defect-engineering zb-InAs based semiconductors, as well as the material design for radiation-tolerant electronics.

scholarly journals Temperature-induced nanostructural evolution of hydrogen-rich voids in amorphous silicon: a first-principles study

Nanoscale ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 1464-1477
Author(s):  
Parthapratim Biswas ◽  
Durga Paudel ◽  
Raymond Atta-Fynn ◽  
Stephen R. Elliott
Keyword(s):  
Ab Initio ◽  
Amorphous Silicon ◽  
First Principles ◽  
First Principles Study

The paper presents an ab initio study of temperature-induced nanostructural evolution of hydrogen-rich voids in amorphous silicon.

scholarly journals Effective n-type F-doped MoSe2 monolayers

RSC Advances ◽  
2017 ◽  
Vol 7 (43) ◽  
pp. 26673-26679 ◽  
Author(s):  
Xu Zhao ◽  
Xiaonan Zhang ◽  
Tianxing Wang ◽  
Shuyi Wei ◽  
Lin Yang
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Structure Formation ◽  
First Principles ◽  
Formation Energy ◽  
Ab Initio Simulation ◽  
Transition Level ◽  
Simulation Package ◽  
First Principles Method

Using a first-principles method, based on the Vienna Ab-initio Simulation Package (VASP), we have studied the electronic structure, formation energy and transition level of a MoSe2 monolayer doped with V and VII atoms.

Silicon-Hydrogen Bonding and Hydrogen Diffusion in Amorphous Silicon

1995 ◽  
Vol 377 ◽  
Author(s):  
Chris G. Van De Walle ◽  
R. A. Street
Keyword(s):  
Activation Energy ◽  
Amorphous Silicon ◽  
First Principles ◽  
Density Functional ◽  
Hydrogen Diffusion ◽  
Chemical Potential ◽  
Energy Levels ◽  
Diffusion Activation Energy ◽  
Quantitative Identification ◽  
Diffusion Activation

ABSTRACTDespite its importance for technological applications, the behavior of hydrogen in amorphous silicon is not fully understood. In particular, the anomalously low activation energy (1.5 eV) for hydrogen diffusion has remained unexplained. We investigate the interaction of hydrogen with dangling bonds using first-principles pseudopotential-density-functional calculations. Our analysis shows that the diffusion activation energy should be measured from the hydrogen chemical potential, and that this level should be identified with the formation energy of Si-H bonds. A quantitative identification of the energy levels with experimental observables is then possible.

First principles study of oxygen vacancies in (Mo + C)-doped anatase TiO2

2015 ◽  
Vol 29 (14) ◽  
pp. 1550072 ◽  
Author(s):  
Jie Cui ◽  
Shuhua Liang ◽  
Xianhui Wang ◽  
Jianmin Zhang
Keyword(s):  
Oxygen Vacancy ◽  
Fermi Level ◽  
Conduction Band ◽  
First Principles ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Anatase Tio2 ◽  
Metallic Behavior ◽  
Structural And Electronic Properties ◽  
Projector Augmented Wave

The structural and electronic properties of neutral oxygen vacancies in ( Mo + C )-doped anatase TiO 2 were investigated using frozen-core projector-augmented wave (PAW) method within GGA +U approximation. Six possible oxygen vacancy sites were considered in the present work. The results show that the octahedral vertex adjacent to Mo and opposite from C is the most stable position for oxygen vacancy based on the results of the formation energy. The Fermi level is located at above the bottom of the conduction band and a typical n-type metallic behavior occurs as a result of the oxygen vacancy appeared in ( Mo + C ) doped TiO 2.

Vacancy-Interstitial Pair-Formation Mechanism of X-Ray-Irradiation-Induced Crystallization in Amorphous Silicon Studied by ab initio Molecular Dynamics Simulation

1995 ◽  
Vol 377 ◽  
Author(s):  
T. Matsumura ◽  
H. Katayama-Yoshida ◽  
N. Orita
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Ab Initio ◽  
Amorphous Silicon ◽  
Formation Energy ◽  
Pair Formation ◽  
Dynamics Simulation ◽  
Ab Initio Molecular Dynamics ◽  
Migration Energy ◽  
X Ray

ABSTRACTWe have studied the microscopic mechanism of the X-ray-irradiation-enhanced crystallization in amorphous silicon (a-Si) based upon an ab initio molecular-dynamics simulation. We find that the bistable dangling-bonds (sp3- and sp2-like structures) exhibit a large lattice relaxation and are strongly related to the X-ray-irradiation-induced vacancy-interstitial-pair formation. The vacancy-interstitial-pair formation reduces the formation energy of the vacancy to zero and enhances the crystallization with small migration energy of the vacancy. The crystallization rate in X-ray-irradiated a-Si is dominated by the migration energy of the vacancy in this mechanism because the formation energy is zero in X-ray-irradiated a-Si and one order of magnitude larger than the migration energy without X-ray irradiation.

scholarly journals Ab initio description of oxygen vacancies in epitaxially strained $$\hbox {SrTiO}_{{3}}$$ at finite temperatures

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zizhen Zhou ◽  
Dewei Chu ◽  
Claudio Cazorla
Keyword(s):  
Thin Films ◽  
Ab Initio ◽  
First Principles ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Compressive Strain ◽  
Random Access ◽  
Critical Energy ◽  
Theoretical Description ◽  
Information Storage

AbstractEpitaxially grown $$\hbox {SrTiO}_{{3}}$$ SrTiO 3 (STO) thin films are material enablers for a number of critical energy-conversion and information-storage technologies like electrochemical electrode coatings, solid oxide fuel cells and random access memories. Oxygen vacancies ($${\mathrm{V}_{{\mathrm{O}}}}$$ V O ), on the other hand, are key defects to understand and tailor many of the unique functionalities realized in oxide perovskite thin films. Here, we present a comprehensive and technically sound ab initio description of $${\mathrm{V}_{{\mathrm{O}}}}$$ V O in epitaxially strained (001) STO thin films. The novelty of our first-principles study lies in the incorporation of lattice thermal excitations on the formation energy and diffusion properties of $${\mathrm{V}_{{\mathrm{O}}}}$$ V O over wide epitaxial strain conditions ($$-4 \le \eta \le +4$$ - 4 ≤ η ≤ + 4 %). We found that thermal lattice excitations are necessary to obtain a satisfactory agreement between first-principles calculations and the available experimental data for the formation energy of $${\mathrm{V}_{{\mathrm{O}}}}$$ V O . Furthermore, it is shown that thermal lattice excitations noticeably affect the energy barriers for oxygen ion diffusion, which strongly depend on $$\eta $$ η and are significantly reduced (increased) under tensile (compressive) strain. The present work demonstrates that for a realistic theoretical description of oxygen vacancies in STO thin films is necessary to consider lattice thermal excitations, thus going beyond standard zero-temperature ab initio approaches.

The role of density reduction in lithiated amorphous silicon: Molecular dynamics and ab-initio studies

2021 ◽  
Author(s):  
Jay Krishan Dora ◽  
Charchit Saraswat ◽  
Ashish Gour ◽  
Sudipto Ghosh ◽  
Natraj Yedla ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Amorphous Silicon ◽  
Density Reduction
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