scholarly journals Raman Spectroscopy of C-Irradiated Graphite

1992 ◽  
Vol 279 ◽  
Author(s):  
D. M. Hembree ◽  
D. F. Pedraza ◽  
G. R. Romanoski ◽  
S. P. Withrow ◽  
B. K. Annis
Keyword(s):  
Raman Spectroscopy ◽  
High Temperature ◽  
Pyrolytic Graphite ◽  
High Dose ◽  
Surface Cracks ◽  
Damage State ◽  
Damage Level ◽  
Atomic Force ◽  
Irradiated Graphite ◽  
High Dose Implantation

ABSTRACTHighly oriented pyrolytic graphite samples were irradiated with C+ ions at 35 keV in a direction normal to the basal plane and subsequently annealed up to 1373 K. Substantial surface topography changes were observed at fluences of 5×1018 ions/m2 and higher using scanning electron and atomic force microscopies. Intricate networks of surface cracks and ridges developed after high dose implantation. A systematic study of the irradiation effects was conducted using Raman spectroscopy. Microstructural changes in irradiated regions were first detected at a dose of 1×1017 ions/m2 through the appearance of the Raman D-line at ∼1360 cm−1. The intensity of this line increases while that of the Raman G-line at 1580 cm−1 decreases as the irradiation dose is increased or the irradiation temperature is decreased. After irradiation at 280K to a fluence of 5×1019 ions/m2 or higher the first order spectrum exhibits one single line at a wavelength intermediate between the D- and G-lines. Damage recovery upon thermal annealing depends not only on the initial damage state but also on the annealing temperature sequence. Samples irradiated to a damage level where two distinct Raman peaks are no longer resolvable exhibited upon direct annealing at a high temperature two distinct Raman lines. By contrast, pre-annealing these highly irradiated specimens at lower temperatures produced less pronounced changes in the Raman spectra. Pre-annealing appears to stabilize damage structures that are more resistant to high-temperature annealing than those induced by irradiation.

An Electrical and Physical Study of Crystal Damage in High-Dose Al- and N-Implanted 4H-SiC

2017 ◽  
Vol 897 ◽  
pp. 411-414 ◽  
Author(s):  
Craig A. Fisher ◽  
Romain Esteve ◽  
Stefan Doering ◽  
Michael Roesner ◽  
Martin de Biasio ◽  
...  
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
High Dose ◽  
Stress Determination ◽  
Analysis Techniques ◽  
Physical Study ◽  
Crystal Damage ◽  
Activation Annealing ◽  
Anneal Temperature ◽  
High Dose Implantation

In this paper, an investigation into the crystal structure of Al-and N-implanted 4H-SiC is presented, encompassing a range of physical and electrical analysis techniques, with the aim of better understanding the material properties after high-dose implantation and activation annealing. Scanning spreading resistance microscopy showed that the use of high temperature implantation yields more uniform resistivity profiles in the implanted layer; this correlates with KOH defect decoration and TEM observations, which show that the crystal damage is much more severe in room temperature implanted samples, regardless of anneal temperature. Finally, stress determination by means of μRaman spectroscopy showed that the high temperature implantation results in lower tensile stress in the implanted layers with respect to the room temperature implantation samples.

Non Destructive Determination of the Threading Dislocation Density of Smooth Simox Substrates using Atomic Force Microscopy

2000 ◽  
Vol 6 (S2) ◽  
pp. 1088-1089
Author(s):  
A. Domenicucci ◽  
R. Murphy ◽  
D. Sadanna ◽  
S. Klepeis
Keyword(s):  
Atomic Force Microscopy ◽  
High Temperature ◽  
Single Crystal Silicon ◽  
Silicon Layer ◽  
High Dose ◽  
Threading Dislocation ◽  
Crystal Silicon ◽  
Force Microscopy ◽  
Atomic Force ◽  
High Temperature Anneal

Atomic force microscopy (AFM) has been used extensively in recent years to study the topographic nature of surfaces in the nanometer range. Its high resolution and ability to be automated have made it an indispensable tool in semiconductor fabrication. Traditionally, AFM has been used to monitor the surface roughness of substrates fabricated by separation by implanted oxygen (SIMOX) processes. It was during such monitoring that a novel use of AFM was uncovered.A SIMOX process requires two basic steps - a high dose oxygen ion implantation (1017 to 1018 cm-3) followed by a high temperature anneal (>1200°C). The result of these processes is to form a buried oxide layer which isolates a top single crystal silicon layer from the underlying substrate. Pairs of threading dislocations can form in the top silicon layer during the high temperature anneal as a result of damage caused during the high dose oxygen implant.

High temperature high-dose implantation of aluminum in 4H-SiC

2004 ◽  
Vol 84 (25) ◽  
pp. 5195-5197 ◽  
Author(s):  
N. S. Saks ◽  
A. V. Suvorov ◽  
D. C. Capell
Keyword(s):  
High Temperature ◽  
High Dose ◽  
High Dose Implantation

Topographical changes induced by high dose carbon-bombardment of graphite

1993 ◽  
Vol 8 (10) ◽  
pp. 2587-2599 ◽  
Author(s):  
B.K. Annis ◽  
D.F. Pedraza ◽  
S.P. Withrow
Keyword(s):  
Dose Rate ◽  
Pyrolytic Graphite ◽  
Surface Region ◽  
Scanning Tunneling ◽  
High Dose ◽  
Near Surface ◽  
Optical Scanning ◽  
Atomic Force ◽  
First Time ◽  
High Shearing

Highly oriented pyrolytic graphite has been implanted at room temperature with 165 keV C+-ions at doses from 6 × 1017 to 3 × 1019 ions/m2. Implantation-induced topographical changes of differing size scales were studied by optical, scanning electron, scanning tunneling, and atomic force microscopies. Defects with atomic resolution are seen for the lower dose implants. The formation of a vacancy line is revealed for the first time. At the higher doses a dendrite-like system of deep surface cracks is observed. This cracking develops as a result of the large basal plane contraction produced by irradiation which generates high shearing stresses between the implanted, damaged surface layer and the underlying material. Two independent systems of ridges have been characterized. One appears to follow a crystallographic direction while the other appears as a dense, intricate, generally curvilinear network with short ramifications. Additional experiments in which both the ion energy and dose rate have been varied indicate that ridge evolution progresses with increased energy and fluence, but is independent of dose rate. It is suggested that the ridge networks may form as a result of C transport by diffusion from the heavily damaged near-surface region or of a tectonic-plate-like motion or both. The geometric features of the ridge networks are related to the subsurface radiation damage as well.

scholarly journals The absence of metamictisation in natural monazite

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Lutz Nasdala ◽  
Shavkat Akhmadaliev ◽  
Boris E. Burakov ◽  
Chutimun Chanmuang N ◽  
Radek Škoda
Keyword(s):  
High Temperature ◽  
Radioactive Waste ◽  
Radiation Damage ◽  
Alpha Particle ◽  
Annealing Temperature ◽  
Irradiation Damage ◽  
Alpha Radiation ◽  
Structural Restoration ◽  
Damage State ◽  
Damage Level

Abstract The actinide-containing mineral monazite–(Ce) is a common accessory rock component that bears petrogenetic information, is widely used in geochronology and thermochronology, and is considered as potential host material for immobilisation of radioactive waste. Natural samples of this mineral show merely moderate degrees of radiation damage, despite having sustained high self-irradiation induced by the decay of Th and U (for the sample studied herein 8.9 ± 0.3 × 1019 α/g). This is assigned to low damage-annealing temperature of monazite–(Ce) and “alpha-particle-assisted reconstitution”. Here we show that the response of monazite–(Ce) to alpha radiation changes dramatically, depending on the damage state. Only in radiation-damaged monazite–(Ce), 4He ions cause gradual structural restoration. In contrast, its high-temperature annealed (i.e. well crystalline) analogue and synthetic CePO4 experience He-irradiation damage. Alpha-assisted annealing contributes to preventing irradiation-induced amorphisation (“metamictisation”) of monazite–(Ce); however, this process is only significant above a certain damage level.

Formation of Crystalline SiC Buried Layer by High-Dose Implantation of MeV Carbon Ions at High Temperature

1993 ◽  
Vol 32 (Part 2, No. 9A) ◽  
pp. L1286-L1288 ◽  
Author(s):  
Akiyoshi Chayahara ◽  
Masato Kiuchi ◽  
Atsushi Kinomura ◽  
Yoshiaki Mokuno ◽  
Yuji Horino ◽  
...  
Keyword(s):  
High Temperature ◽  
High Dose ◽  
Carbon Ions ◽  
Buried Layer ◽  
High Dose Implantation

High Temperature Graphene Formation on Capped and Uncapped SiC

2011 ◽  
Vol 679-680 ◽  
pp. 785-788 ◽  
Author(s):  
Robert Göckeritz ◽  
Denny Schmidt ◽  
Moritz Beleites ◽  
Gerhard Seifert ◽  
Stefan P. Krischok ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Atomic Force Microscopy ◽  
High Temperature ◽  
Surface Morphology ◽  
Epitaxial Graphene ◽  
Argon Pressure ◽  
Slow Heating ◽  
Heating Rates ◽  
Force Microscopy ◽  
Atomic Force

Epitaxial graphene was grown on Si-face 4H-SiC. A SiC pretreatment with a carbon cap¬ping technique was used as well as slow heating rates and a temperature of 1800 °C under atmos¬pheric argon pressure. The surface morphology was investigated by atomic force microscopy and Raman spectroscopy was performed for samples with different graphitization times.

Mesotaxy: Formation of Buried Single-Crystal CoSi2 Layers by Implantation

1986 ◽  
Vol 74 ◽  
Author(s):  
Alice E. White ◽  
K. T. Short ◽  
R. C. Dynes ◽  
J. P. Garno ◽  
J. M. Gibson
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Electrical Characterization ◽  
Rutherford Backscattering ◽  
High Dose ◽  
High Temperature Annealing ◽  
Buried Layers ◽  
High Dose Implantation ◽  
Better Than

AbstractUsing high dose implantation of 200 keV Co ions followed by high temperature annealing, we have created buried layers of CoSi2 in crystalline Si of both (100) and (111) orientations. For a dose of 3 × 1017 Co/cm2, the layer that forms is ∼1100Å thick and the overlying Si is ∼600Å thick. A lower dose of 2 × 1017 Co/cm2 yields a thinner layer, 700Å thick, under 1200Å of crystalline Si. Rutherford Backscattering and channeling analysis of the layers shows that they are aligned with the substrate (χmin of the Co as low as 6.4%.) and TEM inspection of the (100) CoSi2/Si interfaces shows that they are abrupt and epitaxial (with occasional small facets). Moreover, electrical characterization of these layers yields resistance ratios that are better than epitaxial CoSi2 films grown by more conventional UHV methods.

High-temperature high-dose implantation of N+ and Al+ ions in 6H-SiC

1997 ◽  
Vol 23 (8) ◽  
pp. 617-620 ◽  
Author(s):  
R. A. Yankov ◽  
M. Voelskow ◽  
W. Kreissig ◽  
D. V. Kulikov ◽  
J. Pezoldt ◽  
...  
Keyword(s):  
High Temperature ◽  
High Dose ◽  
High Dose Implantation

Lateral Confinement of Silicide Layers Synthesized with High Dose Implantation and Annealing

1989 ◽  
Vol 147 ◽  
Author(s):  
Alice E. White ◽  
K. T. Short ◽  
S. D. Berger ◽  
H. A. Huggins ◽  
D. Loretto
Keyword(s):  
Electron Beam ◽  
High Temperature ◽  
Electron Beam Lithography ◽  
High Dose ◽  
Induced Current ◽  
High Temperature Annealing ◽  
Tem Analysis ◽  
Resolution Electron ◽  
Electron Beam Induced Current ◽  
High Dose Implantation

AbstractUsing mesotaxy, a technique which involves high dose implantation followed by high temperature annealing, we have created narrow wires of CoSi2 buried beneath the surface of a silicon wafer. The implantation masks are fabricated directly on the silicon substrate using high resolution electron beam lithography in combination with reactive ion etching. TEM analysis shows that the wires are single-crystal and oriented with the substrate with very abrupt interfaces. The electrical continuity of the wires has been confirmed with electron-beam-induced current measurements.

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