Elevated Temperature Implantation of GaAs with Si Ions.

1996 ◽  
Vol 438 ◽  
Author(s):  
R. A. Brown ◽  
J. S. Williams
Keyword(s):  
Elevated Temperatures ◽  
Amorphous Layer ◽  
Ion Flux ◽  
Implantation Temperature ◽  
Transmission Electron ◽  
Order Of Magnitude ◽  
Residual Damage ◽  
Radiation Induced ◽  
Small Clusters ◽  
Induced Defects

AbstractThe formation of amorphous layers in GaAs during ion bombardment at elevated temperatures, where dynamic annealing of radiation-induced defects is substantial, is shown to be extremely sensitive to the ion flux, fluence, and implantation temperature. For example, with increasing fluence, damage can first build up extremely slowly, then suddenly collapse to the amorphous phase. Alternatively, for a constant ion fluence, a change in flux by one order of magnitude can change the critical temperature for amorphisation by 27°C, and at constant flux and fluence, a change of only 6°C can alter the residual damage from small clusters barely visible by conventional transmission electron microscopy and Rutherford backscattering to a thick amorphous layer. The temperature at which this occurs is strongly dependent upon the ion flux and fluence.

Elevated Temperature Implantation of GaAs With Si Ions

1996 ◽  
Vol 439 ◽  
Author(s):  
R. A. Bhown ◽  
J. S. Williams
Keyword(s):  
Elevated Temperatures ◽  
Amorphous Layer ◽  
Ion Flux ◽  
Implantation Temperature ◽  
Transmission Electron ◽  
Order Of Magnitude ◽  
Residual Damage ◽  
Radiation Induced ◽  
Small Clusters ◽  
Induced Defects

AbstbactThe formation of amnorphous layers in GaAs during ion bombardment at elevated temperatures, where dynamic annealing of radiation-induced defects is substantial, is shown to be extremely sensitive to the ion flux. fluence. and implantation temperature. For example. with increasing fluence. damage can first build up extremely slowly. then suddenly collapse to the amorphous phase. Alternatively. for a constant ion fluence, a change in flux by one order of magnitude can change the critical temperature for amorphisation by 27°C. and at constant flux and fluence. a change of only 6°C can alter the residual damage from small clusters barely visible by conventional transmission electron microscopy and Rutherlord backscattering to a thick amorphous layer. The temperature at which this occurs is strongly dependent upon the ion flux and fluence.

scholarly journals New microstructural insights into neutron-irradiated tungsten

2020 ◽  
Author(s):  
Michael Dürrschnabel ◽  
Michael Klimenkov ◽  
Ute Jäntsch ◽  
Michael Rieth ◽  
Hans-Christian Schneider ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Fusion Reactors ◽  
Dislocation Loops ◽  
Plasma Facing Components ◽  
Transmission Electron ◽  
Radiation Induced ◽  
Crystallographic Orientation Relationship ◽  
Relationship Of ◽  
Induced Defects

Abstract The development of appropriate materials for fusion reactors that can sustain high neutron fluencies at elevated temperatures remains a great challenge. Tungsten is one of the promising candidate materials for plasma-facing components of future fusion reactors, due to several favorable properties as for example a high melting point, a high sputtering resistivity, and a low coefficient of thermal expansion. The microstructural details of a tungsten sample with a 1.25 dpa (displacements per atom) damage dose after irradiation at 800°C were examined by transmission electron microscopy (TEM). Three types of radiation-induced defects were observed, analyzed and characterized: (i) voids with sizes ranging from 10 nm to 65 nm, (ii) dislocation loops with a size of up to 10 nm and (iii) W-Re-Os containing σ- and χ-type precipitates. The distribution of voids as well as the nature of the occurring dislocation loops were studied in detail. In addition, nano-chemical analyses revealed that the σ- and χ-type precipitates, which are sometimes attached to voids, are surrounded by a solid solution cloud enriched with Re. For the first time the crystallographic orientation relationship of the σ- and χ-phases to the W-matrix was specified. Furthermore, electron energy-loss spectroscopy could not unambiguously verify the presence of He within individual cavities.

scholarly journals New insights into microstructure of neutron-irradiated tungsten

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Dürrschnabel ◽  
M. Klimenkov ◽  
U. Jäntsch ◽  
M. Rieth ◽  
H. C. Schneider ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Fusion Reactors ◽  
Dislocation Loops ◽  
Plasma Facing Components ◽  
Transmission Electron ◽  
Radiation Induced ◽  
Crystallographic Orientation Relationship ◽  
Relationship Of ◽  
Induced Defects

AbstractThe development of appropriate materials for fusion reactors that can sustain high neutron fluence at elevated temperatures remains a great challenge. Tungsten is one of the promising candidate materials for plasma-facing components of future fusion reactors, due to several favorable properties as for example a high melting point, a high sputtering resistivity, and a low coefficient of thermal expansion. The microstructural details of a tungsten sample with a 1.25 dpa (displacements per atom) damage dose after neutron irradiation at 800 °C were examined by transmission electron microscopy. Three types of radiation-induced defects were observed, analyzed and characterized: (1) voids with sizes ranging from 10 to 65 nm, (2) dislocation loops with a size of up to 10 nm and (3) W–Re–Os containing σ- and χ-type precipitates. The distribution of voids as well as the nature of the occurring dislocation loops were studied in detail. In addition, nano-chemical analyses revealed that the σ- and χ-type precipitates, which are sometimes attached to voids, are surrounded by a solid solution cloud enriched with Re. For the first time the crystallographic orientation relationship of the σ- and χ-phases to the W-matrix was specified. Furthermore, electron energy-loss spectroscopy could not unambiguously verify the presence of He within individual voids.

Electrophysical and Optical Properties of 4H-SiC Irradiated with Xe Ions

2013 ◽  
Vol 740-742 ◽  
pp. 625-628
Author(s):  
N. Chuchvaga ◽  
E. Bogdanova ◽  
A. Strelchuk ◽  
Evgenia V. Kalinina ◽  
D.B. Shustov ◽  
...  
Keyword(s):  
High Energy ◽  
Partial Recovery ◽  
Electrical Characteristics ◽  
Stopping Distance ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Radiation Induced ◽  
Temperature Radiation ◽  
Induced Defects ◽  
Partial Annealing

A comparative research of the cathodoluminescence and electrical characteristics of the samples 4H-SiC irradiated with high energy Xe ions (167 MeV) in wide range fluencies 4x109 –1x1011 cm-2 at temperatures 250C and 5000C are presented. After irradiation these samples were thermal annealed at 5000C for 30 min. Far-action effect at a depth of more than one order of magnitude of stopping distance was observed under Xe ions irradiation in 4H-SiC. An increase of the ion Xe fluencies increased the concentration of radiation-induced defects that resulted in rise of the compensation effect of conductivity in samples. Irradiation of 4H-SiC by Xe ions at 5000C was accompanied with "dynamic annealing" some low-temperature radiation-induced defects, which led to a partial recovery of the electrical characteristics of devices. The thermal annealing of irradiated samples led to additional partial annealing of radiation defects, which increases the radiation resource of devices based on 4H-SiC.

Recent Advances in Understanding Helium Embrittlement in Metals

MRS Bulletin ◽  
1986 ◽  
Vol 11 (4) ◽  
pp. 14-18 ◽  
Author(s):  
M.I. Baskes
Keyword(s):  
Radiation Damage ◽  
Fusion Energy ◽  
Bubble Formation ◽  
Pair Potential ◽  
Damage Threshold ◽  
Transmission Electron ◽  
Helium Embrittlement ◽  
Atomistic Calculations ◽  
Radiation Induced ◽  
Induced Defects

Helium is formed in metals as a secondary product of fission/fusion energy technology. Even though helium is chemically inert and essentially insoluble in metals, under specific exposure conditions it is known to cause them to lose their ductility. At high temperatures, helium atoms produced from the transmutation of 10B or from a two-step process with 58Ni in amounts as low as a few parts per million migrate to grain boundaries to cause inter-granular failure. Ion implantation of helium may cause a similar effect. More recently it has been found that helium produced from tritium decay at or slightly above room temperature also markedly degrades the mechanical properties of metals. In order to design alloys of the future it is necessary to understand the mechanisms responsible for this helium embrittlement.Early experiments found that helium is strongly trapped at radiation-produced defects in metals. Atomistic calculations using pair potential interactions verified these findings. It was initially thought that the helium embrittlement in metals was due to the trapping and subsequent bubble formation at radiation-induced defects. It has been shown, however, that helium may be trapped in metals even in the absence of radiation damage. Thomas et al. found that 3He generated at low temperatures from tritium decay remained trapped in nickel upon heating to 500°C. In both this experimentand a subsequentone in gold the helium was introduced without the production of radiation damage. In this second experiment Thomas used transmission electron microscopy to see in the gold small (10Å) bubbles that had been implanted with low-energy (sub-damage threshold) helium.

Temperature Dependence of Damage in Boron-Implanted Silicon

1989 ◽  
Vol 147 ◽  
Author(s):  
G. Ottaviani ◽  
F. Nava ◽  
R. Tonini ◽  
S. Frabboni ◽  
G. F. Cerofolini ◽  
...  
Keyword(s):  
Room Temperature ◽  
Amorphous Layer ◽  
Systematic Investigation ◽  
Vacuum Furnace ◽  
Cross Sectional ◽  
Ion Channeling ◽  
Projected Range ◽  
Transmission Electron ◽  
Boron Implantation ◽  
Residual Damage

AbstractWe have performed a systematic investigation of boron implantation at 30 keV into <100> n-type silicon in the 77 –300 K temperature range and mostly at 9×1015 cm−2 fluence. The analyses have been performed with ion channeling and cross sectional transmission electron microscopy both in as-implanted samples and in samples annealed in vacuum furnace at 500 °C and 850 °C for 30 min. We confirm the impossibility of amorphization at room temperature and the presence of residual damage mainly located at the boron projected range. On the contrary, a continuous amorphous layer can be obtained for implants at 77 K and 193 K; the thickness of the implanted layer is increased by lowering the temperature, at the same time the amorphous-crystalline interface becomes sharper. Sheet resistance measurements performed after isochronal annealing shows an apparent reverse annealing of the dopant only in the sample implanted at 273 K. The striking differences between light and heavy ions observed at room temperature implantation disappears at 77 K and full recovery with no residual damage of the amorphous layer is observed.

Atomistic observation of electron irradiation-induced defects in CeO2

2013 ◽  
Vol 1514 ◽  
pp. 93-98 ◽  
Author(s):  
Seiya Takaki ◽  
Tomokazu Yamamoto ◽  
Masanori Kutsuwada ◽  
Kazuhiro Yasuda ◽  
Syo Matsumura
Keyword(s):  
Electron Irradiation ◽  
Imaging Techniques ◽  
Dark Field ◽  
Dislocation Loops ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
Radiation Induced ◽  
Induced Defects ◽  
Irradiation Induced Defects

ABSTRACTWe have investigated the atomistic structure of radiation-induced defects in CeO2 formed under 200 keV electron irradiation. Dislocation loops on {111} habit planes are observed, and they grow accompanying strong strain-field. Atomic resolution scanning transmission electron microscopy (STEM) observations with high angle annular dark-field (HAADF) and annular bright-field (ABF) imaging techniques showed that no additional Ce layers are inserted at the position of the dislocation loop, and that strong distortion and expansion is induced around the dislocation loops. These results are discussed that dislocation loops formed under electron irradiation are non-stoichiometric defects consist of oxygen interstitials.

Defect Detection in Fe-Cr Alloys with Positron Annihilation Doppler Broadening Spectroscopy

2012 ◽  
Vol 733 ◽  
pp. 270-273 ◽  
Author(s):  
Veronika Sabelová ◽  
Martin Petriska ◽  
Jana Veterníková ◽  
Vladimir Slugeň ◽  
Jarmila Degmová ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Positron Beam ◽  
Quantitative Information ◽  
Structural Defects ◽  
Doppler Broadening ◽  
Positron Energy ◽  
Open Volume ◽  
Order Of Magnitude ◽  
Radiation Induced ◽  
Induced Defects

Positron annihilation Doppler broadening spectroscopy (DBS) has been used for the detection of structural defects in Fe-9wt%Cr (Fe-9Cr) alloy in the as-prepared and implanted states. Defects were created by He and H ion implantation with a kinetic energy of 250 keV. DBS is a non-destructive method and is a unique tool for the observation of open volume defects like vacancies and vacancy clusters in solids. A positron beam with variable positron energy was used for the measurement of defect depth profiles up to 1.5 µm. The obtained results provide qualitative and semi-quantitative information about radiation induced defects and their chemical environment. Although the collision damage from helium implantation was one order of magnitude higher than for the case of hydrogen, the changes in S and W parameters are much less significant, probably due to considerably lower mobility of helium in the implanted materials, which results in helium capture by the created open volume defects.

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