Theory of Point Defects and Complexes in GaN

1995 ◽  
Vol 395 ◽  
Author(s):  
Jörg Neugebauer ◽  
Chris G. Van de Walle
Keyword(s):  
First Principles ◽  
State Of The Art ◽  
Growth Parameters ◽  
Free Carrier ◽  
First Principles Calculations ◽  
Acceptor Doping ◽  
Native Defects ◽  
Chemical Potentials ◽  
Insight Into

ABSTRACTWe have studied the electronic and energetic properties of native defects, impurities and complexes in GaN applying state-of-the-art first-principles calculations. An analysis of the numerical results gives direct insight into defect concentrations and impurity solubility with respect to growth parameters (temperature, chemical potentials) and into the mechanisms limiting the doping levels in GaN. We show how compensation and passivation by native defects or impurities, solubility issues, and incorporation of dopants on other sites influence the acceptor doping levels. The role of hydrogen in enhancing the p-type doping is explained in detail. We also discuss the mechanisms responsible for the experimentally observed limitation of the free-carrier concentration in p-type GaN.

Role Of Hydrogen And Hydrogen Complexes In Doping Of Gan

1996 ◽  
Vol 423 ◽  
Author(s):  
Jörg Neugebauer ◽  
Chris G. Van de wallei
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
State Of The Art ◽  
Growth Conditions ◽  
Fundamental Difference ◽  
First Principles Calculations ◽  
Native Defects ◽  
In Doping ◽  
And Migration

AbstractWe have calculated electronic structure, energetics and migration for hydrogen and hydrogen complexes in GaN employing state-of-the-art first-principles calculations. Using these results in combination with previous detailed investigations about native defects we have calculated the concentration of hydrogen and dopants for different growth conditions. Our results reveal a fundamental difference in the behavior of hydrogen in p-type and n-type material. In particular, we explain why hydrogen has little effect on donor impurities and why H concentrations are low in n-type GaN. We discuss why hydrogen is beneficial for acceptor incorporation in GaN, and identify the limitations of this process.

Theory of Defects in Wide-Band-Gap Semiconductors

1995 ◽  
Vol 378 ◽  
Author(s):  
Chris G Van de Walle ◽  
Jörg Neugebauer
Keyword(s):  
Band Gap ◽  
First Principles ◽  
State Of The Art ◽  
Wide Band ◽  
First Principles Calculations ◽  
Wide Band Gap ◽  
Native Defects ◽  
In Doping ◽  
Wide Band Gap Semiconductors

AbstractWe discuss the application of state-of-the-art first-principles calculations to the problem of defects, impurities, and doping levels in semiconductors. Since doping problems are of particular relevance in wide-band-gap materials, we focus here on studies of ZnSe and GaN. For ZnSe, we discuss our latest insights in the influence of compensation and dopant solubility on the experimentally observed limitation of the free carrier concentration in p-type ZnSe. For GaN, we focus on the role of native defects in doping or compensation of the material, with particular emphasis on the n-type conductivity of as-grown GaN.

Solubility Products for Precipitate Phases in Steels from First-principles Calculations

2011 ◽  
Vol 1296 ◽  
Author(s):  
Tetyana Klymko ◽  
Chaitanya Krishna Ande ◽  
Marcel Sluiter
Keyword(s):  
Ab Initio ◽  
First Principles ◽  
First Principles Calculations ◽  
Experimental Phase Diagram ◽  
Formation Enthalpies ◽  
Enthalpy And Entropy ◽  
Solubility Products ◽  
Diagram Analysis ◽  
Insight Into

ABSTRACTThe work presented gives an insight into using formation enthalpies determined from ab initio calculations for computing solubility products in steels. The role of enthalpy and entropy contributions to the solubility product is discussed. As an illustration of the method, we present solubility products for observed stoichiometric precipitate phases in ferrite from first-principles calculations and in austenite as obtained from the combined approach based on ab initio and experimental phase diagram analysis. The results are compared with experimental data where available.

scholarly journals A DFT investigation of the role of oxygen vacancies on the structural, electronic and magnetic properties of ATiO3 (A = Mn, Fe, Ni) multiferroic materials

2018 ◽  
Vol 20 (45) ◽  
pp. 28382-28392 ◽  
Author(s):  
R. A. P. Ribeiro ◽  
E. Longo ◽  
J. Andrés ◽  
S. R. de Lazaro
Keyword(s):  
Magnetic Properties ◽  
First Principles ◽  
Oxygen Vacancies ◽  
First Principles Calculations ◽  
Deep Insight ◽  
Multiferroic Materials ◽  
Multiferroic Properties ◽  
Surface Models ◽  
Insight Into

In order to achieve deep insight into the multiferroic behavior and electronic properties of intrinsic oxygen vacancies in ATiO3 (A = Mn, Fe, Ni), first-principles calculations were carried out for bulk and non-polar (110) surface models, showing that controlling oxygen vacancies can be a valuable strategy to tailor the multiferroic properties.

Effect of native defects and Co doping on ferromagnetism in HfO2: First-principles calculations

2010 ◽  
Vol 32 (7) ◽  
pp. 1298-1302 ◽  
Author(s):  
Chong Han ◽  
Shi-Shen Yan ◽  
Xue-Ling Lin ◽  
Shu-Jun Hu ◽  
Ming-Wen Zhao ◽  
...  
Keyword(s):  
First Principles ◽  
First Principles Calculations ◽  
Native Defects ◽  
Co Doping

An effective and efficient approach to p-type AlN by Be2:O codoping from first-principles calculations

2016 ◽  
Vol 30 (20) ◽  
pp. 1650257
Author(s):  
Meng Zhao ◽  
Wenjun Wang ◽  
Jun Wang ◽  
Junwei Yang ◽  
Weijie Hu ◽  
...  
Keyword(s):  
First Principles ◽  
Ionization Energy ◽  
Hole Concentration ◽  
Valence Band Maximum ◽  
First Principles Calculations ◽  
Mutual Compensation ◽  
Efficient Approach ◽  
P Type ◽  
Codoping Method

Various Be:O-codoped AlN crystals have been investigated via first-principles calculations to evaluate the role of the different combinations in effectively and efficiently inducing p-type carriers. It is found that the O atom is favored to bond with two Be atoms. The formed Be2:O complexes decrease the acceptor ionization energy to 0.11 eV, which is 0.16 eV lower than that of an isolated Be in AlN, implying that the hole concentration could probably be increased by 2–3 orders of magnitude. The electronic structure of Be2:O-codoped AlN shows that the lower ionization energy can be attributed to the interaction between Be and O. The Be–O complexes, despite failing to induce p-type carriers for the mutual compensation of Be and O, introduce new occupied states on the valence-band maximum (VBM) and hence the energy needed for the transition of electrons to the acceptor level is reduced. Thus, the Be2:O codoping method is expected to be an effective and efficient approach to realizing p-type AlN.

Computational and Experimental Insights into the Role of Acidic Molecules on the Corrosion Behavior on 7A46 Aluminum Alloy

2021 ◽  
Vol 21 (4) ◽  
pp. 2221-2233
Author(s):  
Yaru Liu ◽  
Qinglin Pan ◽  
Xiangdong Wang ◽  
Ye Ji ◽  
Qicheng Liu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Corrosion Behavior ◽  
First Principles ◽  
First Principles Calculations ◽  
Corrosive Media ◽  
Corrosion Depth ◽  
Corrosion Mechanisms ◽  
Nanoscale Level

The corrosion mechanisms for different corrosive media on the aged 7A46 aluminum alloy were systematically investigated at nanoscale level. The combination of empirical intergranular and exfoliation corrosion behavior was employed, and coupled with first-principles calculations. Results revealed that the dispersed distribution of matrix precipitates (MPs) leads to the enhancement of the corrosion resistance pre-ageing (PA) followed by double-ageing (PA-DA) alloy. The deepest corrosion depth of PA-DA alloy was in hydrochloric acid, and the calculation result demonstrates that the passivation effect in combination with the accumulation of corrosion products in nitric acid protect the PA-DA alloy from further corrosion.

First-Principles Investigations of Hydrogen and Fluorine on Silicon Surfaces

1992 ◽  
Vol 259 ◽  
Author(s):  
Chris G. Van De Walle
Keyword(s):  
First Principles ◽  
Etch Rate ◽  
State Of The Art ◽  
Interstitial Impurity ◽  
Silicon Surfaces ◽  
Hydrogen Solubility ◽  
First Principles Calculations ◽  
Energy Diagram

ABSTRACTState-of-the-art first-principles calculations allow detailed studies of the mechanisms by which hydrogen and fluorine interact with silicon. The results for hydrogen are presented in the form of an energy diagram which includes many different configurations. The theoretical values allow a discussion of issues such as hydrogen solubility, and desorption from a Si surface. For fluorine, we investigate the behavior as an interstitial impurity in the bulk, as well as Si-F interactions at or near the surface. A study of the insertion of F atoms into Si-Si bonds elucidates the microscopic mechanisms of etching, and the dependence of etch rate on doping. Thermodynamic aspects of HF etching are briefly discussed.

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