Ion Implant Activation and Redistribution in AlxGa1–xAs

1989 ◽  
Vol 157 ◽  
Author(s):  
S. J. Pearton ◽  
W. S. Hobson ◽  
A. E. Von Neida ◽  
N. M. Haegel ◽  
K. S. Jonesf ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Activation Energy ◽  
Transmission Electron Microscopy ◽  
Electrical Activity ◽  
Mole Fraction ◽  
Electrical Activation ◽  
Dislocation Loops ◽  
Rapid Annealing ◽  
Transmission Electron ◽  
Minimal Damage

ABSTRACTThe electrical activation characteristics of implanted Be, Mg, Si and S in AlxGa1–xAs (x = 0-1) were investigated as a function of ion dose for rapid annealing in the range 600-950°C. The apparent activation energy for electrical activity of these species increases with increasing AlAs mole fraction - for Be, the activation energy is 0.35eV for GaAs and 0.49eV for Al0.54Ga0.46 As. There is no evidence for pairing of Be and O in AlGaAs, in contrast to the situation for GaAs. Self-compensation is the predominant limiting mechanism for Si activation in AlGaAs as determined by the relative photoluminescence intensities of the SiGa-to-SiAs related transitions. No significant redistribution of implanted Si is observed for any AlAs mole fraction for rapid annealing (5 sec) up to 900°C, whereas S shows motion into the AlGaAs and no tendency to outdiffuse. By contrast, both Be and Mg display loss of the dopant to the surface, and little redistribution toward the bulk. Minimal damage is observed by transmission electron microscopy in as-implanted AlGaAs for Be or Si doses below the amorphization threshold. Upon annealing at the conditions for optimum activation, a high density of small dislocation loops is observed near the end of the ion range.

The Microstructure of Transiently Annealed Donor Implants in GaAs

1984 ◽  
Vol 35 ◽  
Author(s):  
M.A. Shahid ◽  
R. Bensalem ◽  
B.J. Sealy
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electrical Activity ◽  
Room Temperature ◽  
Dislocation Loops ◽  
Electrical Measurements ◽  
Ion Energy ◽  
Transmission Electron

ABSTRACTUndoped SI (100) GaAs has been implanted with selenium and tin ions at room temperature at an ion energy of 300 keV and using ion dose in the range 1 × 1014 to 1 × 1015 ions cm−2. Transient annealing at 1000°C and above has been studied using electrical measurements and transmission electron microscopy. The results show that tin implanted samples have comparatively higher values of electrical activity and mobility than those implanted with selenium ions. A difference in the microstructure of these two implants was observed. Selenium implanted samples show dislocation lines and loops possessing 1/2<110> Burgers vectors while tin implanted GaAs contains dislocation loops of 1/2<110> and 1/3<111> types and also dislocation lines having 1/2<110> Burgers vectors. Both types of defect in tin implanted samples are decorated with precipitates.

Structural Defects in Ion Implanted 4H-SiC Epilayers

2000 ◽  
Vol 640 ◽  
Author(s):  
P. O. Å. Persson ◽  
W. Skorupa ◽  
D. Panknin ◽  
A. Kuznetsov ◽  
A. Hallén ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Annealing Process ◽  
Ion Concentration ◽  
Electrical Activation ◽  
Structural Defects ◽  
Dislocation Loops ◽  
Transmission Electron ◽  
Residual Damage ◽  
Vacancy Concentrations

ABSTRACTTransmission electron microscopy (TEM) was used to investigate Al, Ar, C and Si ionimplanted 4H-SiC epilayers. After the implantation the samples were thermally annealed for 30 minutes at 1700°C. During the annealing process dislocation loops are formed and the generation of such dislocation loops upon annealing, is investigated with respect to dopant electrical activation, peak ion concentration and calculated interstitial/vacancy concentrations. It is concluded that the dislocation loops are generated as the result of a combination of residual damage and excess interstitials generated in a “plus one” (+1) process.

Behavior of Metastable Te Donor Concentrations in Q-Switched Ruby Laser Annealed GaAs

1980 ◽  
Vol 1 ◽  
Author(s):  
P. Pianetta ◽  
J. Amano ◽  
G. Woolhouse ◽  
C. A. Stolte
Keyword(s):  
Electron Microscopy ◽  
Activation Energy ◽  
Transmission Electron Microscopy ◽  
Ruby Laser ◽  
Structural Changes ◽  
The Other ◽  
Dislocation Loops ◽  
Transmission Electron ◽  
Half Angle ◽  
Laser Anneal

ABSTRACTThe thermal behavior of Te implanted, laser annealed GaAs was investigated by helium backscattering spectroscopy and transmission electron microscopy in order to correlate structural changes with the two stage reduction in the carrier concentration due to post laser anneal heating above 200°C. The activation energy for stage one which occurs in the range 200–400°C was determined to be approximately 1.3 eV. Post laser anneal heating at 450°C caused no observable structural changes. On the other hand, 850°C post laser anneal heating induced the formation of precipitates and dislocation loops as well as narrowing the channeling half-angle of Te by about 11%.

Annealing Of Radiation Damage in Tungsten

1970 ◽  
Vol 28 ◽  
pp. 412-413
Author(s):  
Robert C. Rau ◽  
John Moteff
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Radiation Damage ◽  
Thermal Annealing ◽  
Neutron Fluence ◽  
Dislocation Loops ◽  
Defect Clusters ◽  
Polycrystalline Tungsten ◽  
Transmission Electron ◽  
Radiation Induced

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.

Black-white contrast of dislocation loops

1978 ◽  
Vol 36 (1) ◽  
pp. 328-329
Author(s):  
J. J. Hren ◽  
W. D. Cooper ◽  
L. J. Sykes
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Loops ◽  
Major Premise ◽  
Burgers Vector ◽  
Transmission Electron ◽  
Primary Means ◽  
Contrast Analysis ◽  
Dot Product ◽  
Imaging Conditions

Small dislocation loops observed by transmission electron microscopy exhibit a characteristic black-white strain contrast when observed under dynamical imaging conditions. In many cases, the topography and orientation of the image may be used to determine the nature of the loop crystallography. Two distinct but somewhat overlapping procedures have been developed for the contrast analysis and identification of small dislocation loops. One group of investigators has emphasized the use of the topography of the image as the principle tool for analysis. The major premise of this method is that the characteristic details of the image topography are dependent only on the magnitude of the dot product between the loop Burgers vector and the diffracting vector. This technique is commonly referred to as the (g•b) analysis. A second group of investigators has emphasized the use of the orientation of the direction of black-white contrast as the primary means of analysis.

scholarly journals Direct Characterization of the Relation between the Mechanical Response and Microstructure Evolution in Aluminum by Transmission Electron Microscopy In Situ Straining

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1431
Author(s):  
Seiichiro Ii ◽  
Takero Enami ◽  
Takahito Ohmura ◽  
Sadahiro Tsurekawa
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Beam ◽  
Elastic Behavior ◽  
Annealed Specimen ◽  
Displacement Curve ◽  
Dislocation Loops ◽  
Transmission Electron ◽  
Stress Drops

Transmission electron microscopy in situ straining experiments of Al single crystals with different initial lattice defect densities have been performed. The as-focused ion beam (FIB)-processed pillar sample contained a high density of prismatic dislocation loops with the <111> Burgers vector, while the post-annealed specimen had an almost defect-free microstructure. In both specimens, plastic deformation occurred with repetitive stress drops (∆σ). The stress drops were accompanied by certain dislocation motions, suggesting the dislocation avalanche phenomenon. ∆σ for the as-FIB Al pillar sample was smaller than that for the post-annealed Al sample. This can be considered to be because of the interaction of gliding dislocations with immobile prismatic dislocation loops introduced by the FIB. The reloading process after stress reduction was dominated by elastic behavior because the slope of the load–displacement curve for reloading was close to the Young’s modulus of Al. Microplasticity was observed during the load-recovery process, suggesting that microyielding and a dislocation avalanche repeatedly occurred, leading to intermittent plasticity as an elementary step of macroplastic deformation.

Structural Investigation of Photoluminescent Porous Si by Transmission Electron Microscopy

1992 ◽  
Vol 281 ◽  
Author(s):  
S. Shih ◽  
K. H. Jung ◽  
D. L. Kwong
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sample Preparation ◽  
Structural Investigation ◽  
Amorphous Material ◽  
Porous Si ◽  
Plan View ◽  
Mesh Structure ◽  
Transmission Electron ◽  
Minimal Damage

ABSTRACTWe have developed a new, minimal damage approach for examination of luminescent porous Si layers (PSLs) by transmission electron microscopy (TEM). In this approach, chemically etched PSLs are fabricated after conventional plan-view TEM sample preparation. A diffraction pattern consisting of a diffuse center spot, characteristic of amorphous material, is primarily observed. However, crystalline, microcrystalline, and amorphous regions could all be observed in selected areas. A crystalline mesh structure could be observed in some of the thin areas near the pinhole. The microcrystallite sizes were 15–150 Å and decreased in size when located further from the pinhole.

Conversion of platelets into dislocation loops and voidite formation in type IaB diamonds

1995 ◽  
Vol 449 (1936) ◽  
pp. 295-313 ◽  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Local Mode ◽  
Diamond Structure ◽  
Dislocation Loops ◽  
X Ray ◽  
Regular Type ◽  
Transmission Electron ◽  
Stable Conditions ◽  
The One

Type la natural diamonds have been heated in the temperature range of 2400-2700°C under stabilizing pressures. The specimens studied are mainly regular type IaB diamonds. Transmission electron microscopy studies of treated speci­mens show that platelets are converted to interstitial ½ a 0 <011> dislocation loops; voidites are also formed. When all the platelets have been converted, the ex­perimental features associated with them also disappear, i. e. the X-ray extra reflections (spikes), the B' local-mode absorption and the lattice absorption in the one-phonon region termed the D spectrum. It is discovered that when diamonds are heated under graphite-stable rather than diamond-stable conditions, the rate of conversion is considerably enhanced; for instance, at 2650°C there is an increase in the rate of about three orders of magnitude. This enhancement is considered to be due to the instability of the diamond structure itself and a reason for this enhancement is suggested.

CoSi2 Precipitate Coarsening During Formation of Buried Epitaxial Cosi2 Layers By Ion Beam Synthesis

1990 ◽  
Vol 201 ◽  
Author(s):  
R. Jebasinski ◽  
S. Mantl ◽  
K. Radermacher ◽  
P. Fichtner ◽  
W. Jăger ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Activation Energy ◽  
Transmission Electron Microscopy ◽  
Cross Section ◽  
Microstructural Evolution ◽  
Annealing Temperature ◽  
Ion Beam ◽  
Precipitate Coarsening ◽  
Annealing Temperatures ◽  
Transmission Electron

AbstractThe coarsening of CoSi2 precipitates and the microstructural evolution of (111) Si implanted with 200 keV Co+ ions at 350°C and fluences of 1×1016cm−2 and 6×1016cm−2 were investigated as a function of depth, annealing temperature and annealing time using Rutherford Backscattering Spectroscopy (RBS) and Transmission Electron Microscopy (TEM). After annealing cross-section TEM micrographs show a layered array of platelet-shaped precipitates with preferred facets on {111} planes. The fraction of Co-atoms, that were redistributed during the different annealing temperatures and times, has been used to determine an activation energy for the precipitate coarsening. By applying the Meechan-Brinkman and the change-of-slope methods, we obtained activation energies in the range of 3.2 – 3.6 eV.

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