Effects of Implantation Temperature on the Structure, Composition and Oxidation Resistance of Sic

1994 ◽  
Vol 354 ◽  
Author(s):  
Zunde Yang ◽  
Honghua Du ◽  
Matthew Libera ◽  
Irwin L. Singer
Keyword(s):  
Electron Microscopy ◽  
Oxidation Resistance ◽  
Room Temperature ◽  
Aluminum Carbide ◽  
High Dose ◽  
Accelerated Oxidation ◽  
Implantation Temperature ◽  
Transmission Electron ◽  
Oxidation Layers ◽  
Flowing Oxygen

Abstractɑ-SiC crystals were implanted with aluminum to a high dose at room temperature or 800°C. Studies by transmission electron microscopy showed that SiC was amorphized by room temperature implantation but remained crystalline at 800°C. Crystalline aluminum carbide was formed and aluminum redistribution took place in SiC implanted at 800°C. Implanted and unimplanted crystals were oxidized in 1 atm flowing oxygen at 1300°C. Amorphization led to accelerated oxidation of SiC. The oxidation resistance of SiC implanted at 800°C was comparable to that of pure SiC. The oxidation layers formed on SiC implanted at both temperatures consisted of silica embedded with mullite precipitates. The phase formation during implantation and oxidation is consistent with thermodynamic predictions.

Effects of implantation temperature on the structure, composition, and oxidation resistance of aluminum-implanted SiC

1995 ◽  
Vol 10 (6) ◽  
pp. 1441-1447 ◽  
Author(s):  
Zunde Yang ◽  
Honghua Du ◽  
Matthew Libera ◽  
Irwin L. Singer
Keyword(s):  
Oxidation Resistance ◽  
Room Temperature ◽  
Aluminum Carbide ◽  
High Dose ◽  
Optimum Range ◽  
Implantation Temperature ◽  
Transmission Electron ◽  
Oxidation Layers ◽  
Flowing Oxygen ◽  
High Aluminum

α-SiC crystals were implanted with aluminum to a high dose at room temperature or 800 °C. Transmission electron microscopy showed that SiC was amorphized by room temperature implantation but remained crystalline after 800 °C implantation. Crystalline aluminum carbide was formed and aluminum redistribution took place in SiC implanted at 800 °C. Implanted and unimplanted crystals were oxidized in 1 atm flowing oxygen at 1300 °C. Amorphization led to accelerated oxidation of SiC. The oxidation resistance of SiC implanted at 800 °C was comparable with that of pure SiC. The oxidation layers formed on SiC implanted at both temperatures consisted of silica embedded with mullite precipitates. The phase formation during implantation and oxidation is consistent with thermodynamic predictions. The results from our current and earlier studies suggest that there exists an optimum range of implantation temperature, probably above 500 °C but below 800 °C, which preserves the substrate crystallinity and retains the high aluminum dosage, for the enhancement of oxidation resistance of SiC.

Room Temperature Damage, Annealing and Dislocation Growth in Silicon

1994 ◽  
Vol 373 ◽  
Author(s):  
R.G. Elliman ◽  
I.V. Mitchell
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Rutherford Backscattering Spectrometry ◽  
Extended Defects ◽  
High Temperature Annealing ◽  
Primary Defect ◽  
Implantation Temperature ◽  
Transmission Electron ◽  
Sensitive Function ◽  
Temperature Damage

AbstractThe concentration of residual defects produced by self ion implantation of silicon has been shown to be a sensitive function of implantation temperature at temperatures near room temperature. In this study samples were heated to temperatures of 20°C and 60°C and implanted with 540 keV Si ions to a fluence of 2x1015Si.cm-2 using a constant scanned ion flux of 0.2 μA.cm-2. The resultant primary defect concentrations, measured by Rutherford backscattering spectrometry and channelling (RBS-C), were 2.3±0.1x1022 cm-l and 1.8±0.2x1021 cm-3, respectively, i.e. a reduction by a factor of σ13 for a temperature increase of 40°C. Such differences were not evident in the concentration of secondary defects formed by annealing these samples at 900°C for 15 minutes: the defect concentrations were equal within the experimental uncertainties of the RBS-C and transmission electron microscopy (TEM) measurements. This result appears to lead to the surprising conclusion that the number of displaced atoms that survive high temperature annealing to form extended defects is largely independent of the dynamic annealing processes operating during implantation but depends instead on parameters which scale with the ion fluence.

High Resolution Transmission Electron Microscopy of Proton Implanted Gallium Arsenide

1985 ◽  
Vol 46 ◽  
Author(s):  
D. K. Sadana ◽  
J. M. Zavada ◽  
H. A. Jenkinson ◽  
T. Sands
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Phenomenological Model ◽  
Room Temperature ◽  
Stacking Faults ◽  
High Dose ◽  
Cross Sectional ◽  
Projected Range ◽  
Transmission Electron

AbstractHigh resolution transmission electron microscopy (HRTEM) has been performed on cross-sectional specimens from high dose (1016 cm−2) H+ implanted (100) GaAs (300 keV at room temperature). It was found that annealing at 500°C created small (20-50Å) loops on {111} near the projected range (Rp)(3.2 μm). At 550-600°C, voids surrounded by stacking faults, microtwins and perfect dislocations were observed near the Rp. A phenomenological model explaining the observed results is proposed.

Scanning and Transmission Electron Microscopy of Human Red Blood Cells

1969 ◽  
Vol 27 ◽  
pp. 44-45
Author(s):  
A.J. Tousimis ◽  
T.R. Padden
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Blood Cells ◽  
Room Temperature ◽  
Type Specimen ◽  
New Combination ◽  
Human Red Blood Cells ◽  
Transmission Electron ◽  
Microscope Slides ◽  
Scanning Electron

The size, shape and surface morphology of human erythrocytes (RBC) were examined by scanning electron microscopy (SEM), of the fixed material directly and by transmission electron microscopy (TEM) of surface replicas to compare the relative merits of these two observational procedures for this type specimen.A sample of human blood was fixed in glutaraldehyde and washed in distilled water by centrifugation. The washed RBC's were spread on freshly cleaved mica and on aluminum coated microscope slides and then air dried at room temperature. The SEM specimens were rotary coated with 150Å of 60:40- gold:palladium alloy in a vacuum evaporator using a new combination spinning and tilting device. The TEM specimens were preshadowed with platinum and then rotary coated with carbon in the same device. After stripping the RBC-Pt-C composite film, the RBC's were dissolved in 2.5N HNO3 followed by 0.2N NaOH leaving the preshadowed surface replicas showing positive topography.

Formation of Dislocation Channels in Neutron Irradiated Molybdenum

1972 ◽  
Vol 30 ◽  
pp. 672-673
Author(s):  
S. Mahajan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ambient Temperature ◽  
Room Temperature ◽  
Channel Formation ◽  
Early Stages ◽  
Transmission Electron ◽  
Three Stages ◽  
Two Stages ◽  
Polycrystalline Molybdenum

The evolution of dislocation channels in irradiated metals during deformation can be envisaged to occur in three stages: (i) formation of embryonic cluster free regions, (ii) growth of these regions into microscopically observable channels and (iii) termination of their growth due to the accumulation of dislocation damage. The first two stages are particularly intriguing, and we have attempted to follow the early stages of channel formation in polycrystalline molybdenum, irradiated to 5×1019 n. cm−2 (E > 1 Mev) at the reactor ambient temperature (∼ 60°C), using transmission electron microscopy. The irradiated samples were strained, at room temperature, up to the macroscopic yield point.Figure 1 illustrates the early stages of channel formation. The observations suggest that the cluster free regions, such as A, B and C, form in isolated packets, which could subsequently link-up to evolve a channel.

TEM processing procedure for a bacillus organism grown on solid media

1990 ◽  
Vol 48 (3) ◽  
pp. 624-625
Author(s):  
Jane Payne ◽  
Philip Coudron
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Fume Hood ◽  
Vacuum Aspiration ◽  
Solid Media ◽  
Transmission Electron ◽  
Solid Agar ◽  
Processing Procedure ◽  
Agar Media ◽  
Rat Bone

This transmission electron microscopy (TEM) procedure was designed to examine a gram positive spore-forming bacillus in colony on various solid agar media with minimal artifact. Cellular morphology and organization of colonies embedded in Poly/Bed 812 resin (P/B) were studied. It is a modification of procedures used for undecalcified rat bone and Stomatococcus mucilaginosus.Cultures were fixed and processed at room temperature (RT) under a fume hood. Solutions were added with a Pasteur pipet and removed by gentle vacuum aspiration. Other equipment used is shown in Figure 3. Cultures were fixed for 17-18 h in 10-20 ml of RT 2% phosphate buffered glutaraldehyde (422 mosm/KgH2O) within 5 m after removal from the incubator. After 3 (30 m) changes in 0.15 M phosphate buffer (PB = 209-213 mosm/KgH2O, pH 7.39-7.41), colony cut-outs (CCO) were made with a scalpel.

A crystallographic analysis of the CoSi/Si(111) interface using Transmission Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 574-575
Author(s):  
A.C. Daykin ◽  
C.J. Kiely ◽  
R.C. Pond ◽  
J.L. Batstone
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Defect Structure ◽  
Room Temperature ◽  
Theoretical Method ◽  
Crystallographic Analysis ◽  
Si Substrate ◽  
Transmission Electron ◽  
Theoretical Predictions

When CoSi2 is grown onto a Si(111) surface it can form in two distinct orientations. A-type CoSi2 has the same orientation as the Si substrate and B-type is rotated by 180° degrees about the [111] surface normal.One method of producing epitaxial CoSi2 is to deposit Co at room temperature and anneal to 650°C.If greater than 10Å of Co is deposited then both A and B-type CoSi2 form via a number of intermediate silicides .The literature suggests that the co-existence of A and B-type CoSi2 is in some way linked to these intermediate silicides analogous to the NiSi2/Si(111) system. The phase which forms prior to complete CoSi2 formation is CoSi. This paper is a crystallographic analysis of the CoSi2/Si(l11) bicrystal using a theoretical method developed by Pond. Transmission electron microscopy (TEM) has been used to verify the theoretical predictions and to characterise the defect structure at the interface.

Synthesis and TEM study of Ag–In–(Eu, Ce) ternary approximants

2009 ◽  
Vol 224 (1-2) ◽  
Author(s):  
Kazue Nishimoto ◽  
Miki Muraki ◽  
Ryuji Tamura
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Transmission Electron

AbstractTernary Ag–In–(Eu, Ce) 1/1 approximants are synthesized and their structures are studied by transmission electron microscopy (TEM). For both the approximants, superlattice spots are clearly observed at room temperature, and the superstructures of the Ag–In–(Eu, Ce) approximants are found to be similar to those of Cd

Dechannealing Study of Nanocrystalline Si:H Layers Produced by High Dose Hydrogen Irradiation of Silicon Crystals

1998 ◽  
Vol 536 ◽  
Author(s):  
V. P. Popov ◽  
A. K. Gutakovsky ◽  
I. V. Antonova ◽  
K. S. Zhuravlev ◽  
E. V. Spesivtsev ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Rutherford Backscattering Spectrometry ◽  
Nanocrystalline Structure ◽  
Structural Defects ◽  
High Dose ◽  
Silicon Crystals ◽  
Strong Energy ◽  
Transmission Electron ◽  
Hydrogen Implantation

AbstractA study of Si:H layers formed by high dose hydrogen implantation (up to 3x107cm-2) using pulsed beams with mean currents up 40 mA/cm2 was carried out in the present work. The Rutherford backscattering spectrometry (RBS), channeling of He ions, and transmission electron microscopy (TEM) were used to study the implanted silicon, and to identify the structural defects (a-Si islands and nanocrystallites). Implantation regimes used in this work lead to creation of the layers, which contain hydrogen concentrations higher than 15 at.% as well as the high defect concentrations. As a result, the nano- and microcavities that are created in the silicon fill with hydrogen. Annealing of this silicon removes the radiation defects and leads to a nanocrystalline structure of implanted layer. A strong energy dependence of dechanneling, connected with formation of quasi nanocrystallites, which have mutual small angle disorientation (<1.50), was found after moderate annealing in the range 200-500°C. The nanocrystalline regions are in the range of 2-4 nm were estimated on the basis of the suggested dechanneling model and transmission electron microscopy (TEM) measurements. Correlation between spectroscopic ellipsometry, visible photoluminescence, and sizes of nanocrystallites in hydrogenated nc-Si:H is observed.

The Effect Of Storage On Platelet Morpholog

1981 ◽  
Author(s):  
A Sturk ◽  
L M Burt ◽  
T Hakvoort ◽  
J W ten cate ◽  
N Crawford
Keyword(s):  
Electron Microscopy ◽  
Membrane Structure ◽  
Room Temperature ◽  
Surface Membrane ◽  
Platelet Concentrates ◽  
Room Temperature Storage ◽  
Short Survival ◽  
Transmission Electron ◽  
Temperature Storage ◽  
Morphological Correlation

Platelet concentrates were stored for one, two or three days at 4°C (unagitated) or room temperature (unagitated and linearly agitated). The morphology of platelets in platelet concentrates, directly after twice washing at room temperature and after 60 min incubation of the washed platelets at 37°C was investigated by both scanning and transmission electron microscopy.Platelets in the freshly prepared concentrates are slightly activated, i.e. show some pseudopod formation. At 4°C platelets rapidly loose their discoid shape. After three days their surface membrane shows extensive folding, they are slightly vacuolated and have lost most of their granules. Incubation of these cold-stored platelets at 37°C does not induce reversal to the discoid shape.Room temperature storage results in reversal of the slight initial platelet activation. After three days unagitated platelets are slightly more vacuolated than platelets stored with agitation. Room temperature storage usually results in remarkably well preserved, discoid platelets. Occasionally however, agitated platelet concentrates contain a high proportion of odd shaped cells. As platelets stored at 4°C did not became discoid after incubation at 37°, the altered membrane structure could provide an explanation for their short survival upon transfusion. Our results also provide a morphological correlation with the slightly better recovery and survival of platelets stored agitated vs.- non-agitated platelets at room temperature.

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