scholarly journals Theory of Hydrogen Reactions in Silicon

1987 ◽  
Vol 104 ◽  
Author(s):  
Chris G. Van De Walle ◽  
Y. Bar-Yam ◽  
S. T. Pantelides
Keyword(s):  
Fermi Level ◽  
Total Energy ◽  
First Principles ◽  
Type Material ◽  
Energy Calculations ◽  
And Migration ◽  
The Stability ◽  
Hydrogen Reactions ◽  
Energy Surfaces ◽  
P Type

ABSTRACTWe report first-principles total-energy calculations for H atoms in a Si lattice. Our results for single H atoms are presented in the form of total-energy surfaces, providing immediate insight in stable positions and migration paths. We examine the stability of different charge states (H+, H0, H−) as a function of Fermi-level position, and its impli-cations for H diffusion in p-type vs. n-type material. The results are used to scrutinize and supplement existing understanding of experimental observations. We also study the co-operative interactions of several H atoms, and propose a novel mechanism for H-induced damage.

Phase Stability of the Sigma Phase in Fe-Cr Based Alloys

1995 ◽  
Vol 408 ◽  
Author(s):  
Marcel Il. F ◽  
Sluiter. Koivan Esfurjani ◽  
Yoshiyuki Kawazoe
Keyword(s):  
Total Energy ◽  
Phase Stability ◽  
First Principles ◽  
Finite Temperature ◽  
Sigma Phase ◽  
Complex Structure ◽  
Unit Cell ◽  
Energy Calculations ◽  
Cluster Variation ◽  
The Stability

AbstractThe FeCr sigma phase is a good example of a complex structure: it. has 30 atoms in the unit cell and 5 inequivalent lattice sites, and it belongs to the class of tetrahedrally close packed structures, also known as Frank-Kaspar structures. So far. such structures have riot been treated within a first-principles statistical thermodynamics framework. It will be shown that dtlme to advances in algorithms and hardware important features of the phase stability of complex phases can be computed. The factors which affect the stability of the sigma phase have been studied using carefully selected supercells for electronic total energy calculations. cluster variation calc:ulations in the tet.rahedron approximation were performed to evaluate the effect of partial disorder and of finite temperature. The preferred occupancy of the 5 lattice sites has been investigated and is compared with experimental determinations.

A Theoretical Study of p-Type Doping of ZnO: Problems and Solutions

2001 ◽  
Vol 666 ◽  
Author(s):  
Yanfa Yan ◽  
S.B. Zhang ◽  
S.J. Pennycook ◽  
S.T. Pantelides
Keyword(s):  
Total Energy ◽  
First Principles ◽  
Theoretical Study ◽  
Energy Calculations ◽  
Defect Complexes ◽  
New Approaches ◽  
Impurity Defect ◽  
Problems And Solutions ◽  
P Type ◽  
Made In

ABSTRACTWe present results of a comprehensive set of first-principles total-energy calculations of native and impurity-defect complexes in ZnO and use these results to elucidate the problems that occur in efforts to achieve p-type doping. The analysis naturally leads to new approaches that are likely to overcome the difficulties. The results provide detailed explanations of recent puzzling observations made in attempts to produce p-type ZnO.

Site preference and atomic ordering in the ternary Rh5Ga2As: first-principles calculations

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Nilanjan Roy ◽  
Sucharita Giri ◽  
Harshit ◽  
Partha P. Jana
Keyword(s):  
Total Energy ◽  
First Principles ◽  
Density Functional ◽  
Structure Type ◽  
Site Preference ◽  
X Ray Diffraction ◽  
Atomic Ordering ◽  
Functional Theory ◽  
The Stability ◽  
Bonding Characteristics

Abstract The site preference and atomic ordering of the ternary Rh5Ga2As have been investigated using first-principles density functional theory (DFT). An interesting atomic ordering of two neighboring elements Ga and As reported in the structure of Rh5Ga2As by X-ray diffraction data only is confirmed by first-principles total-energy calculations. The previously reported experimental model with Ga/As ordering is indeed the most stable in the structure of Rh5Ga2As. The calculation detected that there is an obvious trend concerning the influence of the heteroatomic Rh–Ga/As contacts on the calculated total energy. Interestingly, the orderly distribution of As and Ga that is found in the binary GaAs (Zinc-blende structure type), retained to ternary Rh5Ga2As. The density of states (DOS) and Crystal Orbital Hamiltonian Population (COHP) are calculated to enlighten the stability and bonding characteristics in the structure of Rh5Ga2As. The bonding analysis also confirms that Rh–Ga/As short contacts are the major driving force towards the overall stability of the compound.

scholarly journals Rich p -type-doping phenomena in boron-substituted silicene systems

2020 ◽  
Vol 7 (12) ◽  
pp. 200723
Author(s):  
Hai Duong Pham ◽  
Wu-Pei Su ◽  
Thi Dieu Hien Nguyen ◽  
Ngoc Thanh Thuy Tran ◽  
Ming-Fa Lin
Keyword(s):  
Charge Transfer ◽  
Fermi Level ◽  
Charge Density ◽  
Electronic Properties ◽  
First Principles ◽  
Chemical Environment ◽  
First Principles Calculations ◽  
Density Distributions ◽  
Essential Properties ◽  
P Type

The essential properties of monolayer silicene greatly enriched by boron substitutions are thoroughly explored through first-principles calculations. Delicate analyses are conducted on the highly non-uniform Moire superlattices, atom-dominated band structures, charge density distributions and atom- and orbital-decomposed van Hove singularities. The hybridized 2 p z –3 p z and [2s, 2 p x , 2 p y ]–[3s, 3 p x , 3 p y ] bondings, with orthogonal relations, are obtained from the developed theoretical framework. The red-shifted Fermi level and the modified Dirac cones/ π bands/ σ bands are clearly identified under various concentrations and configurations of boron-guest atoms. Our results demonstrate that the charge transfer leads to the non-uniform chemical environment that creates diverse electronic properties.

Increase in Open-circuit Voltage and Improved Stability of Organic Solar Cells by Inserting a Molybdenum Trioxide Buffer Layer

2009 ◽  
Vol 1154 ◽  
Author(s):  
Hideyuki Murata ◽  
Yoshiki Kinoshita ◽  
Yoshihiro Kanai ◽  
Toshinori Matsushima ◽  
Yuya Ishii
Keyword(s):  
Solar Cells ◽  
Buffer Layer ◽  
Organic Solar Cells ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Type Material ◽  
Type Layer ◽  
Improved Stability ◽  
The Stability ◽  
P Type

AbstractWe report the increase in open-circuit voltage (Voc) by inserting of MoO3 layer on ITO substrate to improve built-in potential of organic solar cells (OSCs). In the OSCs using 5,10,15,20-tetraphenylporphyrine (H2TPP) as a p-type material and C60 as a n-type material, the Voc effectively increased from 0.57 to 0.97 V as increasing MoO3 thickness. The obtained highest Voc (0.97 V) is consistent with the theoretical value estimated from the energy difference between the LUMO (−4.50 eV) of C60 and the HOMO (−5.50 eV) of H2TPP layer. Importantly, the enhancement in the Voc was achieved without affecting the short-circuit current density (Jsc) and the fill-factor (FF). Thus, the power conversion efficiency of the device linearly increased from 1.24% to 1.88%. We also demonstrated that a MoO3 buffer layer enhances the stability of OSCs after photo-irradiation. We have investigated the stability of OSCs using H2TPP and N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine as a p-type layer. The both devices with MoO3 layer showed improved stability. These results clearly suggest that the interface at ITO/p-type layer affects the device stability.

Real-space implementation of nonlocal pseudopotentials for first-principles total-energy calculations

1991 ◽  
Vol 44 (23) ◽  
pp. 13063-13066 ◽  
Author(s):  
R. D. King-Smith ◽  
M. C. Payne ◽  
J. S. Lin
Keyword(s):  
Total Energy ◽  
First Principles ◽  
Real Space ◽  
Energy Calculations

Stability and migration of transmutation atoms (H/He) in Ti3AlC2: first principles calculations

RSC Advances ◽  
2016 ◽  
Vol 6 (64) ◽  
pp. 59875-59881 ◽  
Author(s):  
Shutong Yang ◽  
Nengwen Hu ◽  
Xueqiang Gou ◽  
Canglong Wang ◽  
Xiaolu Zhu ◽  
...  
Keyword(s):  
First Principles ◽  
First Principles Calculations ◽  
And Migration ◽  
The Stability

The stability and migration behaviors of impurity H and He atoms have been investigated by using first principles calculations in Ti3AlC2.

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