Correlation of Dislocation Loop Formation and Time Dependent Diffusion of Implanted P-type Dopants in Gallium Arsenide

1991 ◽  
Vol 240 ◽  
Author(s):  
H. G. Robinson ◽  
M. D. Deal ◽  
D. A. Stevenson ◽  
K. S. Jones
Keyword(s):  
Gallium Arsenide ◽  
Time Dependence ◽  
Point Defect ◽  
Dislocation Loop ◽  
Time Dependent ◽  
Dislocation Loops ◽  
Loop Formation ◽  
Interstitial Diffusion ◽  
Order Of Magnitude ◽  
P Type

ABSTRACTRecent experimental results indicate that diffusion of implanted p-type dopants in GaAs is time dependent under certain conditions. For Mg implanted at a dose of 1 × 1014 cm−2, the diffusion is constant for approximately an hour, then decreases by an order of magnitude or more. Be implanted at 1 × 1013 and 1 ×1014 cm−2 exhibits similar behavior, but with a shorter time before the diffusivity decreases. The diffusivity in 1 × 1013 Mg cm−2 implants, in contrast, remains constant for up to 16 hours. TEM micrographs of Be and Mg implants reveal dislocation loops in the higher dose samples, but not in the lower dose ones. During annealing, the loops grow and decrease in density, eventually disappearing completely from the crystal. This annealing of the loops appears to correlate to the time dependence of the diffusion. This behavior can be explained in terms of the substitutional-interstitial diffusion (SID) mechanism and point defect equilibria.

Point Defect Absorption and Dislocation Loop Formation at Grain Boundaries in Hvem-Irradiated Zr and Its Alloys:1. Influence of Solute Addition

1985 ◽  
Vol 43 ◽  
pp. 350-351
Author(s):  
R.A. Herring ◽  
M. Griffiths ◽  
M.H Loretto ◽  
R.E. Smallman
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Point Defect ◽  
Reactor Core ◽  
Solute Concentration ◽  
Nuclear Industry ◽  
Dislocation Loops ◽  
Loop Formation ◽  
Component Material ◽  
Impurity Interaction

Because Zr is used in the nuclear industry to sheath fuel and as structural component material within the reactor core, it is important to understand Zr's point defect properties. In the present work point defect-impurity interaction has been assessed by measuring the influence of grain boundaries on the width of the zone denuded of dislocation loops in a series of irradiated Zr alloys. Electropolished Zr and its alloys have been irradiated using an AEI EM7 HVEM at 1 MeV, ∼675 K and ∼10-6 torr vacuum pressure. During some HVEM irradiations it has been seen that there is a difference in the loop nucleation and growth behaviour adjacent to the grain boundary as compared with the mid-grain region. The width of the region influenced by the presence of the grain boundary should be a function of the irradiation temperature, dose rate, solute concentration and crystallographic orientation.

The Effect of a Thin Sample on the Extended Defect Evolution in Si+ Implanted Si

1997 ◽  
Vol 490 ◽  
Author(s):  
Jing-Hong Li ◽  
Kevin S. Jones
Keyword(s):  
Dislocation Loop ◽  
Ex Situ ◽  
Dissolution Process ◽  
Dislocation Loops ◽  
Loop Formation ◽  
Thin Sample ◽  
Extended Defect ◽  
Defect Evolution ◽  
Annealing Study

ABSTRACTThe annealing kinetics of implant damage in Si+ implanted Si has been investigated using in-situ and ex-situ annealing of transmission electron microscopy (TEM) samples prepared prior to annealing. The defect evolution at 800°C was studied for a Si wafer implanted with Si+ at 100keV to a dose of 2×1014 cm-2. This implant was above the sub-threshold loop formation threshold allowing one to study simultaneously the {311} defect dissolution and dislocation loop nucleation and growth. In order to study the effect on the defect evolution of using a thin sample for an in-situ annealing experiment, a pair of samples, one thick and one thinned into a TEM sample, were annealed in a furnace simultaneously. It was found that the presence of a second surface 2000Å below the implant damage did not affect the extended defect evolution. For the in-situ annealing study it was found that the {311} dissolution process and sub-threshold dislocation loop formation process was not affected by the TEM electron beam at 160kV as long as an 800°C furnace pre-anneal was done prior to in-situ annealing. The dissolution rate of the {311} defects was used to confirm the TEM holder furnace temperature. The results of both the in-situ the {311} defects is released during the 311 dissolution process and 30% comes to reside in dislocation loops. Thus, the loops appear to contain a significant fraction of the total interstitial concentration introduced by the implant.

scholarly journals Terahertz Emission of Gallium Arsenide on Textured p-type Silicon (100) Substrates Grown via Molecular Beam Epitaxy

2018 ◽  
Vol 1 (1) ◽  
pp. 7
Author(s):  
Karl Cedric P. Gonzales ◽  
Karim M. Omambac ◽  
Elizabeth Ann P. Prieto ◽  
Jessica Pauline C. Afalla ◽  
Maria Herminia M. Balgos ◽  
...  
Keyword(s):  
Gallium Arsenide ◽  
Molecular Beam Epitaxy ◽  
Potassium Hydroxide ◽  
Molecular Beam ◽  
Surface Texturing ◽  
Volume Ratio ◽  
Type Silicon ◽  
Order Of Magnitude ◽  
Wet Chemical ◽  
P Type

This study presents the terahertz (THz) emission of molecular beam epitaxy (MBE)-grown Gallium Arsenide (GaAs) on surface textured p-type Silicon (p- Si) (100) substrates. Surface texturing was achieved by anisotropic wet chemical etching using 5% wt Potassium Hydroxide (KOH): Isopropyl alcohol (IPA) (50:1) solution for 15, 30, 45, and 60 minutes. Reflectivity measurements for the textured p-Si(100) substrates indicated that the overall texturing increases with longer etching times. Raman spectroscopy of the post-growth samples confirmed GaAs growth. The THz emission intensities were the same order of magnitude. The GaAs grown on p-Si(100) textured for 60 minutes exhibited the most intense THz emission attributed to the increased absorption from a larger surface-to-volume ratio due to surface texturing. All GaAs on textured p-Si(100) samples had frequency bandwidth of ~2.5 THz.

Modeling Threading Dislocation Loop Nucleation and Evolution in MeV Boron Implanted Silicon

2001 ◽  
Vol 669 ◽  
Author(s):  
Ibrahim Avci ◽  
Mark E. Law ◽  
Craig Jasper ◽  
Hernan A. Rueda ◽  
Rainer Thoma
Keyword(s):  
Normal Distribution ◽  
Point Defect ◽  
Dislocation Loop ◽  
Threading Dislocation ◽  
Dislocation Loops ◽  
Statistical Nature ◽  
Statistical Point ◽  
Simulation Results ◽  
Log Normal ◽  
Log Normal Distribution

ABSTRACTA single statistical point defect based model for the nucleation and evolution of dislocation loops during annealing in Si is developed. The model assumes that the radius and the density of dislocation loops follow a log normal distribution. The loop nucleation part of the model also assumes that all the loops come from {311} unfaulting. The model is verified with the experimental results obtained by studying the formation of dislocation loops and threading dislocation loops as a function of implant condition in boron implanted silicon by varying the dose from 1×1013 to 5×1014 cm−2 at an energy of 1.5 MeV. Due to the statistical nature of the model, the threading dislocation loop density is easily obtained from simulation results. The dramatic change in the threading dislocation loop density withthe increasing implant dose is also predicted by the simulations.

Microstrucutural Characterization of RPV Steels Irradiated to High Fluences

2009 ◽  
Author(s):  
Minoru Tomimatsu ◽  
Hiroyuki Sakamoto ◽  
Kenji Dohi ◽  
Toshiyuki Watanabe ◽  
Hiroshi Matsuzawa
Keyword(s):  
Dislocation Loop ◽  
Structural Integrity ◽  
Neutron Radiation ◽  
Dislocation Loops ◽  
Loop Formation ◽  
Term Operation ◽  
Integrity Assessment ◽  
High Fluences ◽  
Water Reactors ◽  
Property Changes

Neutron radiation embrittlement of reactor pressure vessel (RPV) steels is one of critical issues for the structural integrity assessment of the RPVs. Especially, the embrittlement at high fluences is of great interest for the long term operation of light water reactors because information on the mechanical property changes as well as embrittlement mechanisms is limited at high fluences. In this study, microstructural analyses were conducted on the RPV steels irradiated to high fluences in order to confirm the applicability of the trend curve at high fluence region. Steels investigated are five base metals and a weld metal with their copper content ranging from 0.02 to 0.25 wt. %. These steels were irradiated in the material test reactors to fluence up to 1.3 × 1020 n/cm2, E > 1MeV, at temperature of about 290 °C. After irradiation, transmission electron microscope (TEM) observations were performed to characterize the nano-meter scale microstructural changes due to irradiation. Formation of dislocation loops was observed. Number density and diameter of dislocation loop was investigated. Effects of chemical composition of steel and fluence on dislocation loop formation are discussed.

On the interpretation of dislocation-loop growth during in-situ high-voltage Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 532-533
Author(s):  
E. Holzäpfel ◽  
F. Phillipp ◽  
M. Wilkens
Keyword(s):  
Point Defect ◽  
Rate Equations ◽  
Rate Theory ◽  
Dislocation Loops ◽  
High Voltage Electron Microscopy ◽  
Vacancy Migration ◽  
Voltage Electron ◽  
Reaction Rate Theory ◽  
Defect Reactions

During in-situ radiation damage experiments aiming on the investigation of vacancy-migration properties interstitial-type dislocation loops are used as probes monitoring the development of the point defect concentrations. The temperature dependence of the loop-growth rate v is analyzed in terms of reaction-rate theory yielding information on the vacancy migration enthalpy. The relation between v and the point-defect production rate P provides a critical test of such a treatment since it is sensitive to the defect reactions which are dominant. If mutual recombination of vacancies and interstitials is the dominant reaction, vαP0.5 holds. If, however, annihilation of the defects at unsaturable sinks determines the concentrations, a linear relationship vαP is expected.Detailed studies in pure bcc-metals yielded vαPx with 0.7≾×≾1.0 showing that besides recombination of vacancies and interstitials annihilation at sinks plays an important role in the concentration development which has properly to be incorporated into the rate equations.

TEM investigation of defect reduction and etch pit formation in GaN

2003 ◽  
Vol 798 ◽  
Author(s):  
Angelika Vennemann ◽  
Jens Dennemarck ◽  
Roland Kröger ◽  
Tim Böttcher ◽  
Detlef Hommel ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Dislocation Density ◽  
Line Tension ◽  
Threading Dislocations ◽  
Dislocation Loops ◽  
Etch Pits ◽  
Defect Reduction ◽  
Transmission Electron ◽  
Order Of Magnitude ◽  
Edge Dislocations

ABSTRACTGaN samples of this study were chemically wet etched to gain easier access to the dislocation sturcture. The scanning electron microscopy and transmission electron microscopy investigations revealed four different types of etch pits. After brief etching, several dislocations with screw component showed large etch pits, which may be correlated with the core of the screw dislocation. By means of SiNx micromasking the dislocation density could be reduced by more than one order of magnitude. The reduction of threading dislocations in the SiNx region in GaN grown on 〈0001〉 sapphire is due to bending of the threading dislocations into the {0001} plane, such that they form dislocation loops if they meet dislocations with opposite Burgers vectors. Accordingly, the achievable reduction of the dislocation density is limited by the probability that these dislocations interact. Edge dislocations bend more easily on account of their low line tension. This results in a preferential bending and reduction of dislocations with edge character.

scholarly journals MINIMAL VARIATION OF DEFECT STRUCTURE DUE TO THE ORDER OF ROOM TEMPERATURE HYDROGEN ISOTOPE IMPLANTATION AND SELF-ION IRRADIATION IN NICKEL

MRS Advances ◽  
2016 ◽  
Vol 1 (42) ◽  
pp. 2887-2892
Author(s):  
Brittany Muntifering ◽  
Jianmin Qu ◽  
Khalid Hattar
Keyword(s):  
Dislocation Loop ◽  
Hydrogen Isotope ◽  
Room Temperature ◽  
Ion Irradiation ◽  
In Situ Tem ◽  
Loop Formation ◽  
Radiation Induced ◽  
Formation And Evolution ◽  
And Performance ◽  
Induced Defects

ABSTRACTThe formation and stability of radiation-induced defects in structural materials in reactor environments significantly effects their integrity and performance. Hydrogen, which may be present in significant quantities in future reactors, may play an important role in defect evolution. To characterize the effect of hydrogen on cascade damage evolution, in-situ TEM self-ion irradiation and deuterium implantation was performed, both sequentially and concurrently, on nickel. This paper presents preliminary results characterizing dislocation loop formation and evolution during room temperature deuterium implantation and self-ion irradiation and the consequence of the sequence of irradiation. Hydrogen isotope implantation at room temperature appears to have little or no effect on the final dislocation loop structures that result from self-ion irradiation, regardless of the sequence of irradiation. Tilting experiments emphasize the importance of precise two-beam conditions for characterizing defect size and structure.

Non-equilibrium point defect model for time-dependent passivation of metal surfaces

2001 ◽  
Vol 46 (22) ◽  
pp. 3387-3396 ◽  
Author(s):  
Balaji Krishnamurthy ◽  
Ralph E. White ◽  
Harry J. Ploehn
Keyword(s):  
Equilibrium Point ◽  
Point Defect ◽  
Metal Surfaces ◽  
Time Dependent ◽  
Defect Model ◽  
Point Defect Model ◽  
Non Equilibrium
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