Anisotropy of damage productions in electron irradiated molybdenum

1978 ◽  
Vol 36 (1) ◽  
pp. 354-355
Author(s):  
K. Izui ◽  
S. Furuno ◽  
H. Otsu ◽  
T. Nishida ◽  
H. Maeta
Keyword(s):  
Electron Flux ◽  
Threshold Energy ◽  
High Energy ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
Displacement Threshold ◽  
The Mean ◽  
Channeling Effect ◽  
Different Origins ◽  
Threshold Energies

Anisotropy of damage productions in crystals due to high energy electron bombardment are caused from two different origins. One is an anisotropic displacement threshold energy, and the other is an anisotropic distribution of electron flux near the atomic rows in crystals due to the electron channeling effect. By the n-beam dynamical calculations for germanium and molybdenum we have shown that electron flux at the atomic positions are from ∽4 to ∽7 times larger than the mean incident flux for the principal zone axis directions of incident 1 MeV electron beams, and concluded that such a locally increased electron flux results in an enhanced damage production. The present paper reports the experimental evidence for the enhanced damage production due to the locally increased electron flux and also the results of measurements of the displacement threshold energies for the <100>,<110> and <111> directions in molybdenum crystals by using a high voltage electron microscope.

scholarly journals Timing Performance Simulation for 3D 4H-SiC Detector

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 46
Author(s):  
Yuhang Tan ◽  
Tao Yang ◽  
Kai Liu ◽  
Congcong Wang ◽  
Xiyuan Zhang ◽  
...  
Keyword(s):  
Time Resolution ◽  
High Energy Physics ◽  
3D Structure ◽  
Three Dimensional ◽  
Threshold Energy ◽  
Atomic Displacement ◽  
High Energy ◽  
Simulation Software ◽  
Design And Optimization ◽  
Displacement Threshold

To meet the high radiation challenge for detectors in future high-energy physics, a novel 3D 4H-SiC detector was investigated. Three-dimensional 4H-SiC detectors could potentially operate in a harsh radiation and room-temperature environment because of its high thermal conductivity and high atomic displacement threshold energy. Its 3D structure, which decouples the thickness and the distance between electrodes, further improves the timing performance and the radiation hardness of the detector. We developed a simulation software—RASER (RAdiation SEmiconductoR)—to simulate the time resolution of planar and 3D 4H-SiC detectors with different parameters and structures, and the reliability of the software was verified by comparing the simulated and measured time-resolution results of the same detector. The rough time resolution of the 3D 4H-SiC detector was estimated, and the simulation parameters could be used as guideline to 3D 4H-SiC detector design and optimization.

The evolution of damage structures under simultaneous dual beam irradiation by ions and electrons in a HVEM

1990 ◽  
Vol 48 (4) ◽  
pp. 510-511
Author(s):  
Heishichiro Takahashi ◽  
Soumei Ohnuki ◽  
Takashi Suzuki ◽  
Yasuyoshi Hidaka ◽  
Akimichi Hishinuma
Keyword(s):  
Stainless Steels ◽  
Fusion Reactor ◽  
High Energy ◽  
Beam Irradiation ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
Dual Beam ◽  
Simultaneous Irradiation ◽  
Damage Structure ◽  
Cold Worked

It is well-kncwn that the materials for fusion reactor are damaged by high energy neutrons and other energy particles , and that due to nuclear reaction of (n,α) and (n,p) helium and hydrogen are introduced in the materials. Therefore, it is inportant to see the simultaneous effects of these fission productes and damage defects in materials to develope the fusion materials. To simulate the behaviors of damage structure in fusion reactor, the simultaneous dual beam irradiation is the most convenient method.In order to investigate the effects of hydrogen and helium on the behaviors of defect clustering and void (cavity) formation under the dual beam irradiation, i. e. the simultaneous irradiation with hydrogen or helium ions and electrons was carried out using a high voltage electron microscope with 1000 KeV in the temperature range of 673 k and 823 K for the cold worked and annealed 316 stainless steels. Also, to see the effect of the ratio of hydrogen per dpa,H+ (or He+)/dpa ratio was changed between 0 and 300 appm H+ or He.

Computer Simulation of Displacement Damage in Silicon Carbide

2004 ◽  
Vol 851 ◽  
Author(s):  
R. Devanathan ◽  
F. Gao ◽  
W. J. Weber
Keyword(s):  
Silicon Carbide ◽  
Radiation Effects ◽  
Threshold Energy ◽  
High Energy ◽  
Dynamics Simulation ◽  
Displacement Damage ◽  
Energy Cascades ◽  
Displacement Threshold ◽  
Atom Energy ◽  
Shed Light

ABSTRACTWe have performed molecular dynamics simulation of displacement events on silicon and carbon sublattices in silicon carbide for displacement doses ranging from 0.005 to 0.5 displacements per atom. Our results indicate that the displacement threshold energy is about 21 eV for C and 35 eV for Si, and amorphization can occur by accumulation of displacement damage regardless of whether Si or C is displaced. In addition, we have simulated defect production in high-energy cascades as a function of the primary knock-on atom energy and observed features that are different from the case of damage accumulation in Si. These systematic studies shed light on the phenomenon of non-ionizing energy loss that is relevant to understanding space radiation effects in semiconductor devices.

scholarly journals Anisotropic Displacement Threshold Energies in Silicon by Molecular Dynamics Simulations

1990 ◽  
Vol 209 ◽  
Author(s):  
LeAnn A. Miller ◽  
David K. Brice ◽  
Anil K. Prinja ◽  
S. Thomas Picraux
Keyword(s):  
Molecular Dynamics ◽  
Theoretical Model ◽  
Molecular Dynamics Simulations ◽  
Radiation Effects ◽  
Threshold Energy ◽  
Molecular Beam Epitaxial ◽  
Displacement Threshold ◽  
Dynamics Simulations ◽  
Molecular Beam Epitaxial Growth ◽  
Threshold Energies

AbstractA combination of molecular dynamics simulations and theoretical modeling was used to examine the orientation dependent threshold energies for displacement of silicon atoms from their lattice site due to energetic particle collisions. These results are important for a detailed understanding of both radiation effects in silicon devices and beam-enhanced stimulation of molecular beam epitaxial growth.The molecular dynamics code developed for this study, which employs a Tersoff interaction potential, as well as the theoretical model that incorporates the symmetry of the crystal are described.Bulk displacement threshold energies were determined by the molecular dynamics code for four directions through the open face in the <111>. These values were then incorporated into the theoretical model for the average bulk displacement threshold energy. The average bulk displacement threshold energy was found to be 14.8 eV in 30° about <111> and 11.1 eV in 20° about <100>.

The orientation effect on amorphization in CoTi under 1 MeV electron irradiation

1991 ◽  
Vol 49 ◽  
pp. 1126-1127
Author(s):  
Genbao Xu ◽  
M. Meshii ◽  
P. R. Okamoto
Keyword(s):  
Electron Irradiation ◽  
Electron Flux ◽  
Incident Beam ◽  
Orientation Effect ◽  
Electron Dose ◽  
Voltage Electron ◽  
Arc Melting ◽  
Orientation Effects ◽  
High Voltage Electron Microscope ◽  
Deviation From Stoichiometry

Since the first report of electron irradiation induced amorphization in 1982, this phenomenon has been characterized in many aspects. The effects of the dose and temperature, the mass of the incident beam, the deviation from stoichiometry and the electron flux, have been studied. There is, however, no systematic study has been reported on the crystallographic orientation effects. This paper will report the orientation effect on amorphization of intermetallic compound CoTi irradiated by 1 MeV electrons.An alloy button of Co-45 at.% Ti was prepared by arc-melting and subsequently annealed at 1100°C for ten days. The HVEM samples were spark-cut from the button and then thinned by double jetpolishing in the solution of 15%HCLO4 and methanol. The irradiation was carried out with fully focused 1 MeV electron beam in a high voltage electron microscope. The critical electron dose for complete amorphization and its temperature dependence have been determined for <111>, <110> and <001> orientations.

Experimental and calculated atomic displacement threshold energies for binary semiconductors

1969 ◽  
Vol 310 (1502) ◽  
pp. 319-339 ◽  
Keyword(s):  
Electron Energy ◽  
Emission Band ◽  
Threshold Energy ◽  
Atomic Displacement ◽  
Incident Electron ◽  
Incident Electron Energy ◽  
Atomic Displacements ◽  
Displacement Threshold ◽  
Radiation Annealing ◽  
Threshold Energies

A theory for the production of atomic displacements in binary solids by mono-energetic electrons has been developed to yield an expression which may be numerically integrated to give the number of atomic displacements produced at a particular incident electron energy. The theory is applicable to thick samples and for incident electron energies up to the secondary displacement threshold. The variation with incident electron energy of the computed numbers of displaced primary atoms for various displacement threshold energies has been correlated with experimentally induced and determined point defect concentrations and used to give a precise value of the threshold energy for a primary atomic displacement. The atomic displacements were produced by the use of mono-energetic electrons from a 100 to 400 keV Van de Graaff accelerator. The production of point defects was observed experimentally and evaluated quantitatively by photoluminescence or cathodoluminescence techniques. Displacement of tellurium in cadmium telluride was monitored using corresponding changes in the photoluminescence intensity of the 1.13 μ m emission band. No radiation annealing was observed to take place at the electron doses used and a displacement threshold energy of 7.9 ± 0.1 eV was determined for tellurium. Displacement of sulphur in cadmium sulphide was monitored using the changes in the cathodoluminescence intensity of the 1.02 μ m emission band. In this case radiation annealing occurred to such an extent that a phenomenological theory, described here, had to be developed to correct for it. A sulphur displacement threshold energy of 9.6 ± 0.1 eV was determined. In conclusion, it should be stated that direct techniques such as photoluminescence or cathodoluminescence may be used to investigate quantitatively the production of atomic displacements in binary solids and to give a precise determination for displacement threshold energies.

Simulation of electron displacement damage in the high voltage electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 372-373
Author(s):  
S. Ono ◽  
K. Kanaya
Keyword(s):  
Rest Mass ◽  
Threshold Energy ◽  
High Energy ◽  
Maximum Energy ◽  
Incident Electron ◽  
Electron Dose ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Energy And Momentum ◽  
Image Position

By applying the fundamental theory of the neutron cooling to the conservation law of energy and momentum, the average transferred energy Ea of an atom caused by high energy electrons is given by Ea=Em/2.72, where Em is the maximum energy transferred in a head-on collision.The threshold energy ETH of the incident electron for the displaced atom is obtained from , where Ed is the average displacement energy of an atom with mass M, Es sublimation energy instead of the binding energy by Cosslett, m electron rest mass and c light velocity (Fig.1).When the energy of the incident electron exceeds the threshold energy ETH of displacements the concentration Cd of displaced atoms produced can be given by Cd=σDΦN, where σD is the cross section for the knock-on process, Φ the electron dose, and the total number N of displaced atoms summing over all collisions giving by Keywell as

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