Enhanced Dissolution Of Extrinsic Dislocation Loops In Silicon Annealed In NH3

1996 ◽  
Vol 442 ◽  
Author(s):  
S. B. Herner ◽  
V. Krishnamoorthy ◽  
K. S. Jones ◽  
T. K. Mogi ◽  
H.-J. Gossmann
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Marked Decrease ◽  
Dislocation Loops ◽  
Enhanced Dissolution ◽  
Transmission Electron ◽  
Extrinsic Dislocation ◽  
Good Agreement

AbstractThe behavior of extrinsic dislocation loops in silicon was investigated by transmission electron microscopy. Loops were formed by an amorphizing implant and recrystallization anneal of Si wafers. Wafers were further annealed in either Ar or NH3. Wafers annealed in NH3 formed a thin (∼4 nm) SiNx film. The loops in samples in Ar showed a constant net number of interstitials bound by the loops, while those in samples annealed in NH3 showed a marked decrease. The results are explained by a supersaturation of vacancies recombining with the interstitials in loops. By integrating the measured difference between interstitials bound by the loops in samples annealed in Ar vs. NH3 over the distance from the surface to the loop layer, an estimate for the relative vacancy supersaturation is extracted. Comparison with estimates of vacancy supersaturations with nitridation from the change in Sb diffusivity show good agreement between the two methods.

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.

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.

The Effect of Cryorolling on the Microstructure of Al-Cu-Mg Alloy

2016 ◽  
Vol 877 ◽  
pp. 188-193 ◽  
Author(s):  
Li Wei Quan ◽  
Wen Ning Mu ◽  
Lei Kang ◽  
Xiao Ma ◽  
Peng Han ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Yield Strength ◽  
Optical Microscopy ◽  
Room Temperature ◽  
Solution Treatment ◽  
Mg Alloy ◽  
Dislocation Loops ◽  
Transmission Electron

A precipitation hardenable Al-Cu-Mg alloy was cryorolled with liquid nitrogen followed solution treatment and then aged at 170 ̊C for different time. The microstructure was characterized by optical microscopy (OM) and transmission electron microscopy (TEM). Hardness and tensile strength were also tested. The dislocation loops in the cryorolled alloy are more than the room temperature rolled alloy. Meanwhile the hardness, yield strength and tensile strength are larger than the room temperature rolled alloy.

Stability of Heavily Doped Si Formed by As+ Implantation and Rapid Thermal Annealing

1985 ◽  
Vol 52 ◽  
Author(s):  
Muhammad Z. Numan ◽  
Z. H. Lu ◽  
W. K. Chu ◽  
D. Fathy ◽  
J. J. Wortman
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Thermal Annealing ◽  
Dislocation Loops ◽  
Sheet Resistivity ◽  
Furnace Annealing ◽  
Transmission Electron ◽  
Heavily Doped ◽  
Sheet Resistance Measurement ◽  
Short Time

ABSTRACTDeactivation of ion implanted and rapid thermal annealed (RTA) metastable arsenic in silicon during subsequent furnace annealing has been studied by sheet resistance measurement, Rutherford backs cat t ering/ channeling (RBS), and transmission electron microscopy (TEM). Following RTA, thermal annealing induces deactivation of the dopant which increases the sheet resistivity monotonically with temperature for a very short time, Dislocation loops are formed near the peak of As concentration at post-anneal temperatures of 750°C or higher, where deactivation rate is fast. At lower temperatures deactivation is accompanied by displacement of As atoms, possibly forming clusters.

scholarly journals Effect of He-appm/DPA ratio on the damage microstructure of tungsten

MRS Advances ◽  
2016 ◽  
Vol 1 (42) ◽  
pp. 2893-2899 ◽  
Author(s):  
R.W. Harrison ◽  
H. Amari ◽  
G. Greaves ◽  
J.A. Hinks ◽  
S.E. Donnelly
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
Dislocation Loops ◽  
Vacancy Clusters ◽  
Transmission Electron ◽  
Damage Structure ◽  
Ordered Array ◽  
20 Nm

AbstractIn-situ ion irradiation and transmission electron microscopy has been used to examine the effects of the He appm to DPA ratio, temperature and dose on the damage structure of tungsten (W). Irradiations were performed with 15 or 60 keV He+ ions, achieving He-appm/displacements per atom (DPA) ratios of ∼40,000 and ∼2000, respectively, at temperatures between 500 and 1000°C to a dose of ∼3 DPA. A high number of small dislocation loops with sizes around 5–20 nm and a He bubble lattice were observed for both He-appm/DPA ratios at 500°C with a bubble size ∼1.5 nm. Using the g.b=0 criterion the loops were characterised as b = ±1/2<111> type. At 750°C bubbles do not form an ordered array and are larger in size compared to the irradiations at 500°C, with a diameter of ∼3 nm. Fewer dislocation loops were observed at this temperature and were also characterised to be b = ±1/2<111> type. At 1000°C, no dislocation loops were observed and bubbles grew as a function of fluence attributed to vacancy mobility being higher and vacancy clusters becoming mobile.

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