Point defect formation near the epitaxial Ge(001) growth surface and the impact on phosphorus doping activation

2021 ◽  
Vol 130 (12) ◽  
pp. 125702
Author(s):  
Anurag Vohra ◽  
Geoffrey Pourtois ◽  
Roger Loo ◽  
Wilfried Vandervorst
Keyword(s):  
Point Defect ◽  
Defect Formation ◽  
Growth Surface ◽  
Phosphorus Doping ◽  
The Impact

scholarly journals Machine Learning Based Methodology to Predict Point Defect Energies in Multi-Principal Element Alloys

2021 ◽  
Vol 8 ◽  
Author(s):  
Anus Manzoor ◽  
Gaurav Arora ◽  
Bryant Jerome ◽  
Nathan Linton ◽  
Bailey Norman ◽  
...  
Keyword(s):  
Machine Learning ◽  
Point Defect ◽  
Defect Formation ◽  
Binary Alloys ◽  
Face Centered Cubic ◽  
Principal Element ◽  
Defect Energy ◽  
Defect Energies ◽  
And Migration ◽  
The Impact

Multi-principal element alloys (MPEAs) are a new class of alloys that consist of many principal elements randomly distributed on a crystal lattice. The random presence of many elements lends large variations in the point defect formation and migration energies even within a given alloy composition. Compounded by the fact that there could be exponentially large number of MPEA compositions, there is a major computational challenge to capture complete point-defect energy phase-space in MPEAs. In this work, we present a machine learning based framework in which the point defect energies in MPEAs are predicted from a database of their constituent binary alloys. We demonstrate predictions of vacancy migration and formation energies in face centered cubic ternary, quaternary and quinary alloys in Ni-Fe-Cr-Co-Cu system. A key benefit of building this framework based on the database of binary alloys is that it enables defect-energy predictions in alloy compositions that may be unearthed in future. Furthermore, the methodology enables identifying the impact of a given alloying element on the defect energies thereby enabling design of alloys with tailored defect properties.

Energetics of point defect formation in Ni3Al

2002 ◽  
Vol 46 (1) ◽  
pp. 37-41 ◽  
Author(s):  
Hannes Schweiger ◽  
Olga Semenova ◽  
Walter Wolf ◽  
Wolfgang Püschl ◽  
Wolfgang Pfeiler ◽  
...  
Keyword(s):  
Point Defect ◽  
Defect Formation

scholarly journals On the ab initio calculation of vibrational formation entropy of point defect: the case of the silicon vacancy

2017 ◽  
Vol 8 ◽  
pp. 85505 ◽  
Author(s):  
Pia Seeberger ◽  
Julien Vidal
Keyword(s):  
Point Defect ◽  
First Principles ◽  
Defect Formation ◽  
Finite Size ◽  
Direct Calculation ◽  
Finite Size Effects ◽  
Numerical Errors ◽  
Silicon Vacancy ◽  
Size Dependent ◽  
Very High

Formation entropy of point defects is one of the last crucial elements required to fully describe the temperature dependence of point defect formation. However, while many attempts have been made to compute them for very complicated systems, very few works have been carried out such as to assess the different effects of finite size effects and precision on such quantity. Large discrepancies can be found in the literature for a system as primitive as the silicon vacancy. In this work, we have proposed a systematic study of formation entropy for silicon vacancy in its 3 stable charge states: neutral, +2 and –2 for supercells with size not below 432 atoms. Rationalization of the formation entropy is presented, highlighting importance of finite size error and the difficulty to compute such quantities due to high numerical requirement. It is proposed that the direct calculation of formation entropy of VSi using first principles methods will be plagued by very high computational workload (or large numerical errors) and finite size dependent results.

Analysis and Suppression of Process-Induced Defects in Memory Devices.

2000 ◽  
Vol 610 ◽  
Author(s):  
R. Annunziata ◽  
R. Bottini ◽  
P. Colpani ◽  
C. Cremonesi ◽  
G. Ghidini ◽  
...  
Keyword(s):  
Point Defect ◽  
Defect Density ◽  
Amorphous Layer ◽  
High Dose ◽  
Thermal Treatments ◽  
Memory Devices ◽  
Layer Width ◽  
Implantation Energy ◽  
Induced Defects ◽  
The Impact

AbstractIn this paper we show that dopant decoration of process-induced defects is responsible for a failure mechanism of memory devices. From the electrical point-of-view, the defect-related failure consists in a source-to-drain resistive path formed by junction piping. This mechanism is made active by the very close spacing which is typical of present device structures. A device-like test structure is used for defect detection. This structure proves to be a very effective tool for studying the impact of various process steps on defect generation, in that it allowes statistical data about the formation of these defects to be collected. TEM analyses are extensively used for studying the evolution of end-of-range defects during subsequent thermal treatments and for measuring the amorphous layer width under various implantation conditions.The role of high dose implantations in the generation of this sort of defects is discussed. Even if the amorphous layer is completely recovered by a suitable recristallization annealing, residual defects grow and become dopant-decorated during post-implantation thermal treatments. Defect density is increased by oxidizing treatments. In this case point defect injection is active both in enhancing dopant diffusion and in growing defects.Defect formation is suppressed if the amorphous layer is made very shallow (≤ 50 nm) by suitable choices of the screen oxide and of the implantation energy. A binary collision code is used in order to estimate the dependence on energy of the self-interstitial excess outside the amorphous region. The results of these calculations indicate that defect suppression can be tentatively explained by point defect annihilation at the silicon surface.

Native Point Defect Densities and Dark Line Defects in ZnSe

1995 ◽  
Vol 408 ◽  
Author(s):  
M. A. Berding ◽  
A. Sher ◽  
M. Van Schilfgaarde
Keyword(s):  
Free Energy ◽  
Point Defect ◽  
Defect Formation ◽  
Local Density ◽  
Full Potential ◽  
Nonradiative Recombination ◽  
Dark Line ◽  
Frenkel Defect ◽  
Native Point Defect ◽  
Defect Densities

AbstractNative point defect densities (including vacancies, antisites and interstitials) in ZnSe are calculated using a quasichemical formalism, including both vibrational and electronic contributions to the defect free energy. The electronic contribution to the defect formation free energy is calculated using the self-consistent first-principles full-potential linearized muffin-tin orbital (FP-LMTO) method and the local-density approximation (LDA). Gradient corrections are included so that absolute reference to zinc atoms in the vapor phase can be made. We find that the Frenkel defect formation energy is ∼0.3 eV lower at a stacking fault than in the bulk lattice. Nonradiative-recombination-induced Frenkel defect generation at stacking faults is proposed as a mechanism responsible for the limited device lifetimes.

Austenite Decomposition Kinetics in Laser-Hybrid Welding of Steel of Strength Class K52

2019 ◽  
Vol 946 ◽  
pp. 950-955 ◽  
Author(s):  
A.I. Romantsov ◽  
M.A. Fedorov ◽  
D.G. Lodkov
Keyword(s):  
Welded Joints ◽  
Strength Class ◽  
Defect Formation ◽  
Welding Process ◽  
Decomposition Kinetics ◽  
Hybrid Welding ◽  
Austenite Decomposition ◽  
Laser Hybrid Welding ◽  
Laser Hybrid ◽  
The Impact

A modern technology for joining materials welding is commonly used in various industries. It is a process of interaction of thermal, mechanical and metallurgical properties and behaviors. Complex phenomena, such as solidification, microstructural changes and defect formation, have a great impact on the quality of welded joints. This article presents the results of studying the features of the austenite decomposition kinetics in the application of laser-hybrid welding technology, in a combination with multi-arc automatic submerged arc welding. The cooling rates are determined, affecting the change in properties of HAZ of welded joints on pipe steel of strength class K52. Using the dilatometric method, studies were conducted and thermo-kinetic and structural diagrams were constructed. Analysis of diagrams and microstructures showed that, as a result of the impact of the laser-hybrid welding process in the area of HAZ, the decomposition of austenite occurs mainly in the martensitic zone, followed by the formation of a bainite-perlite structure, due to recrystallization from the heat generated by the facing seams.

Dynamics of point defect formation, clustering and pit initiation on the pyrite surface

2014 ◽  
Vol 127 ◽  
pp. 416-426 ◽  
Author(s):  
F.W. Herbert ◽  
A. Krishnamoorthy ◽  
W. Ma ◽  
K.J. Van Vliet ◽  
B. Yildiz
Keyword(s):  
Point Defect ◽  
Defect Formation ◽  
Pyrite Surface ◽  
Pit Initiation
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