Properties of Gallium Disorder and Gold Implants in GaN

2000 ◽  
Vol 647 ◽  
Author(s):  
W. Jiang ◽  
W.J. Weber ◽  
S. Thevuthasan ◽  
V. Shutthanandan
Keyword(s):  
Rutherford Backscattering Spectrometry ◽  
High Mobility ◽  
Surface Region ◽  
Intermediate Stage ◽  
Near Surface ◽  
Projected Range ◽  
Implantation Damage ◽  
The Mean ◽  
Fluence Range

AbstractEpitaxial single-crystal GaN films on sapphire were implanted 60° off the <0001> surface normal with 1 MeV Au2+ or 3 MeV Au3+ over a fluence range from 0.88 to 86.2 ions/nm2 at 180 and 300 K. The implantation damage was studied in-situ using 2 MeV He+ Rutherford backscattering spectrometry in channeling geometry (RBS/C). The disordering rate in the near- surface region is faster than at the damage peak. In all cases, results show an intermediate stage of Ga disorder saturation at the damage peak. During the thermal annealing at 870 K for 20 min, some Au implants in GaN diffuse into the amorphized surface region, while the remaining Au atoms distribute around the mean ion-projected-range. These results suggest a high mobility of both Ga defects and Au implants in GaN. Deeper damage implantation by 3 MeV Au3+ indicates that GaN cannot be completely amorphized up to the highest ion fluence (86.2 ions/nm2) applied at 300 K.

Damage Response to Irradiation Temperature and Ion Fluence In C+-Irradiated 6H-SiC

1998 ◽  
Vol 540 ◽  
Author(s):  
W. Jiang ◽  
W.J. Weber ◽  
S. Thevuthasan
Keyword(s):  
Thermal Equilibrium ◽  
Surface Region ◽  
Irradiation Temperature ◽  
Angular Width ◽  
Crystallographic Axis ◽  
Near Surface ◽  
Damage Response ◽  
Minimum Yield ◽  
Fluence Range

AbstractIrradiation experiments have been performed 60° off the surface normal for 6H-SiC single crystals at various temperatures (185-870 K) using 550 keV C+ ions over a fluence range from 1×1018 to 5×109 ions/m2. Atomic disorder on the Si sublattice, as determined by in-situ RBS/channeling analysis, ranged from dilute defects to complete amorphization. The critical amorphization dose of ∼0.23 dpa (on the Si sublattice) at 185 K has been determined. Asymmetric shapes in angular yield profiles across the crystallographic axis <0001> emerged above 1.5×1019 C−/m2 (∼0.05 dpa in the near-surface region), which might be associated with the lattice disturbance in the crystal structure. A gradual decrease in half-angular width was observed with the increase of ion fluence in the experiment. The minimum yield exhibits a rather linear relationship with ion dose at the surface. Post-irradiation annealing at the irradiation temperature did not result in measurable recovery for fluences ranging from 4 × 1018 to 2×1019 C+/m2 at 300, 470 and 670 K. Results also show that low fluence (<8×1018 C+/m2) irradiation at 185 K followed by thermal annealing results in similar defect concentrations to irradiation at that same temperature to the same ion fluence. Thus, at low fluences, the accumulated defects are in thermal equilibrium with the structure.

Damage Accumulation in MgAl2O4 Crystals by Xe Ion Irradiations

1993 ◽  
Vol 316 ◽  
Author(s):  
N. Yu ◽  
M. Nastasi ◽  
M.G. Hollander ◽  
C.R. Evans ◽  
C.J. Maggiore ◽  
...  
Keyword(s):  
Temperature Effect ◽  
Damage Accumulation ◽  
Rutherford Backscattering Spectrometry ◽  
Surface Region ◽  
Irradiation Damage ◽  
Spinel Layer ◽  
Near Surface ◽  
Ion Channeling ◽  
Significant Temperature

ABSTRACTWe have studied the damage kinetics in single crystal MgAl2O4 (spinel) with (100) orientation under 370 keV Xe ion irradiations at temperatures of -100 and 400 C. In-situ Rutherford Backscattering Spectrometry (RBS) and ion channeling have been used to monitor the damage accumulation in spinel following sequential Xe ion irradiations. A significant temperature effect on the irradiation damage has been found. Channeling data show that at -100 C, the irradiated spinel layer reaches the same level as in a random spectrum at a dose of 8×1015 Xe/cm2 (20 DPA for peak damage), while at 400 C, the near surface region (50 nm) remains single-crystalline up to 2×1016 Xe/cm2.

Nanoscale Mechanical Properties of In-Situ Tribofilms Generated from ZDDP and F-ZDDP with and without Antioxidants

2007 ◽  
Vol 7 (12) ◽  
pp. 4378-4390 ◽  
Author(s):  
Anuradha Somayaji ◽  
Ramoun Mourhatch ◽  
Pranesh B. Aswath
Keyword(s):  
Electron Microscopy ◽  
Wear Debris ◽  
Surface Region ◽  
Nucleation And Growth ◽  
Near Surface ◽  
Transmission Electron ◽  
Dialkyl Dithiophosphates ◽  
Wear Tests ◽  
Diphenyl Amine

Tribofilms with thickness ranging from 100–200 nm were developed in-situ during wear tests using a zinc dialkyl dithiophosphates (ZDDP) and fluorinated ZDDP (F-ZDDP). The influence of the antioxidant alkylated diphenyl amine on the formation and properties of these tribofilm is examined. Results indicate that the thickness of the tribofilms formed when F-ZDDP is used is always thicker than the tribofilm formed with ZDDP. In addition, in the presence of antioxidants the tribofilm thickness is increased. The hardness of these tribofilms in the absence of the antioxidants is significantly higher at the near surface region (0–30 nm) when compared to the films formed in the presence of antioxidant. Nanoscratch tests conducted to examine the abrasion resistance of the tribofilms also indicate that the tribofilms formed by F-ZDDP are more resistant to scratch compared to films formed by ZDDP. In the presence of antioxidant, tribofilms formed by F-ZDDP are significantly thicker while both films behave in a similar fashion in nanoscratch tests. Transmission electron microscopy of the wear debris formed during the tests were examined and results indicate the nucleation and growth of nanoparticles of Fe3O4 with an approximate size of 5–10 nm embedded within an otherwise amorphous tribofilm.

Modification of The Near-Surface Region Of Al2O3 By Ion Implantation

1983 ◽  
Vol 24 ◽  
Author(s):  
C. W. White ◽  
G. C. Farlow ◽  
H. Naramoto ◽  
C. J. Mchargue ◽  
B. R. Appleton
Keyword(s):  
Mechanical Properties ◽  
Ion Implantation ◽  
Thermal Annealing ◽  
Structural Property ◽  
Surface Region ◽  
Impurity Incorporation ◽  
Near Surface ◽  
Implantation Damage ◽  
Property Changes

ABSTRACTPhysical and structural property changes resulting from ion implantation and thermal annealing of α-A12O3 are reviewed. Emphasis is placed on damage production during implantation, damage recovery during thermal annealing, and impurity incorporation during thermal annealing. Physical and structural property changes caused by ion implantation and annealing are correlated with changes in the mechanical properties.

Ion Implantation Damage and Annealing in GaSb

1993 ◽  
Vol 316 ◽  
Author(s):  
S. Iyer ◽  
R. Parakkat ◽  
B. Patnaik ◽  
N. Parikh ◽  
S. Hegde
Keyword(s):  
Ion Implantation ◽  
Surface Damage ◽  
Liquid Nitrogen Temperature ◽  
Amorphous Layer ◽  
Implantation Technique ◽  
Near Surface ◽  
Projected Range ◽  
Implantation Damage ◽  
Pb Ions ◽  
Better Than

ABSTRACTIon implantation technique is being investigated as an alternate technique for doping GaSb. Hence an understanding of the production and removal of the damage is essential. In this paper, we report on the damages produced by implantation of Te, Er, Hg and Pb ions into undoped (100) GaSb single crystals and their recovery by Rutherford backscattering (RBS)/channeling. The implantations of 1013 to 1013 ions/cm2 in GaSb were done at liquid nitrogen temperature at energies corresponding to the same projected range of 447Å. A comparison of the damage produced by the different ions and their recovery was made by RBS/channeling along <100> axis of GaSb. Near surface damage equivalent to that of an amorphous layer was observed even at lower doses. Upon annealing at 600°C for 30 sec., the Te implanted samples showed best recovery compared to others (Xmin = 11%), the value of Xmin being better than those normally observed in unimplanted Te-doped substrates.

In situ X-ray diffraction study of stacking fault formation in the near-surface region of transformation induced plasticity steels

2013 ◽  
Vol 530 ◽  
pp. 105-112 ◽  
Author(s):  
David Rafaja ◽  
Christina Krbetschek ◽  
Daria Borisova ◽  
Gerhard Schreiber ◽  
Volker Klemm
Keyword(s):  
Diffraction Study ◽  
Surface Region ◽  
Stacking Fault ◽  
X Ray Diffraction ◽  
Near Surface ◽  
Transformation Induced Plasticity ◽  
X Ray

scholarly journals In situ XRD measurements to explore phase formation in the near surface region

2019 ◽  
Vol 126 (20) ◽  
pp. 200901 ◽  
Author(s):  
Darina Manova ◽  
Stephan Mändl
Keyword(s):  
Phase Formation ◽  
Surface Region ◽  
Near Surface ◽  
In Situ Xrd

scholarly journals Effects of Wave Breaking on the Near-Surface Profiles of Velocity and Turbulent Kinetic Energy

2004 ◽  
Vol 34 (2) ◽  
pp. 490-504 ◽  
Author(s):  
Arne Melsom ◽  
Øyvind SÆtra
Keyword(s):  
Surface Stress ◽  
Wave Breaking ◽  
Traditional Approach ◽  
Surface Region ◽  
Breaking Waves ◽  
Stokes Drift ◽  
Surface Velocity ◽  
Momentum Exchange ◽  
Near Surface ◽  
The Mean

Abstract A theoretical model for the near-surface velocity profile in the presence of breaking waves is presented. Momentum is accumulated by growing waves and is released upon wave breaking. In effect, such a transition is a process involving a time-dependent surface stress acting on the mean current. In this paper, conventional theory for the Stokes drift is expanded to fourth-order accuracy in wave steepness. It is shown that the higher-order terms lead to an enhancement of the surface Stokes drift and a slight retardation of the Stokes volume flux. Furthermore, the results from the wave theory are used to obtain a bulk parameterization of momentum exchange during the process of wave breaking. The mean currents are then obtained by application of a variation of the “level 2.5” turbulence closure theory of Mellor and Yamada. When compared with the traditional approach of a constant surface stress, the mean Eulerian current exhibits a weak enhancement in the near-surface region, compensated by a negative shift deeper in the water column. However, it is found that the results of Craig and Banner and the results of Craig are not significantly affected by the present theory. Hence, this study helps to explain why the Craig and Banner model agrees well with observations when a realistic, time-varying surface stress acts on the drift currents.

In Situ Metal Matrix Composite Surfacing by Laser Surface Alloying

2011 ◽  
Vol 227 ◽  
pp. 84-91
Author(s):  
Jyotsna Dutta Majumdar
Keyword(s):  
Metal Matrix Composite ◽  
Matrix Composite ◽  
Metal Matrix ◽  
Composite Layer ◽  
Metallic Matrix ◽  
Surface Region ◽  
Present Contribution ◽  
Near Surface ◽  
In Situ Reactions

Laser as a source of focused energy may be applied for the modification of microstructure and/or composition of the near surface region of a component. The technique may be applied for the development of a ceramic/intermetallics/interstitial compound dispersed metal matrix composite layer on the surface of metallic substrate by melting the substrate with a high power laser and simultaneous addition of alloy powders for the development of metal matrix composite layer by in-situ reactions. In the present contribution, development of metal-dispersed and intermetallic-dispersed matrix composite layer on the surface of metallic matrix has been discussed with a suitable example of its application.

Analysis of Numerical Simulation on Near Surface Beneath Clean and Contaminated Small-Scale Wind-Driven Water Waves

2007 ◽  
Author(s):  
Xiaoxia Hu ◽  
Ali Dolatabadi ◽  
Kamran Siddiqul
Keyword(s):  
Numerical Model ◽  
Water Waves ◽  
Numerical Study ◽  
Surface Region ◽  
Surface Flow ◽  
Small Scale ◽  
Mean Velocity ◽  
Near Surface ◽  
The Mean ◽  
Good Agreement

We report on a numerical study conducted to investigate the near-surface flow beneath clean and contaminated small-scale wind-driven water surfaces. The numerical model is validated in terms of the velocity and surface wave characteristics. A good agreement is observed between the experimental and numerical values. The results from the numerical model show that the mean velocity in the near-surface region is 25–50% higher beneath the contaminated surface as compared to the clear surface. The present trend is also in agreement with the previous experimental observations.

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