scholarly journals Relative Stability of Silicon Self-Interstitial Defects

2000 ◽  
Vol 610 ◽  
Author(s):  
G. Subramanian ◽  
K.S. Jones ◽  
M.E. Law ◽  
M.J. Caturla ◽  
S. Theiss ◽  
...  
Keyword(s):  
Relative Stability ◽  
Defect Size ◽  
Dislocation Loops ◽  
Transmission Electron ◽  
Perfect Dislocation ◽  
Recent Transmission ◽  
Interstitial Defects ◽  
Annealing Study ◽  
Formation Energies ◽  
Weber Potential

Abstract{311) defects and dislocation loops are formed after ion-implantation and annealing of a silicon wafer. Recent Transmission Electron Microscopy studies by Li and Jones have shown that sub-threshold dislocation loops nucleate from {311} defects. In our study, the conjugate gradient method with the Stillinger Weber potential is used to relax different configurations such as {311} defects with a maximum of five chains and perfect dislocation loops. From the formation energies thus obtained we find that there is an optimal width for each length of the {311} defects. Moreover the relative stability of {311}s and loops is studied as a function of defect size. We observe that at very small sizes the perfect loops are more stable than the {311}s. This may provide an explanation for the experimental observation by Robertson et al that, in an annealing study of end of range damage of amorphized samples, 45% of the loops had nucleated in the first 10 minutes of anneal. Out of these 25% of the loops could not have nucleated by unfaulting of {311}s. We propose that homogeneous nucleation, as against unfaulting of the {311}s, could be the source of these sub-microscopic loops.

The Influence of the Initial Supersaturation of Si Interstitial Atoms on the Relative Thermal Stability of Dislocation Loops in Silicon

2000 ◽  
Vol 610 ◽  
Author(s):  
F. Cristiano ◽  
B. Colombeau ◽  
B. de Mauduit ◽  
F. Giles ◽  
M. Omri ◽  
...  
Keyword(s):  
Relative Stability ◽  
Thermal Evolution ◽  
Dislocation Loops ◽  
Transmission Electron Microscopy Analysis ◽  
Transmission Electron ◽  
Interstitial Atoms ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Implantation Process ◽  
Formation Energies

AbstractIn this work, we have studied the relative stability of perfect (PDLs) and faulted (FDLs) dislocation loops formed during annealing of preamorphised silicon. In particular, we have investigated the effect of the initial supersaturation of Si interstitial atoms (Si(int)s) created by the implantation process on their thermal evolution. Transmission Electron Microscopy analysis shows that in samples with a low Si interstitial supersaturation, FDLs are the dominant defects while PDLs appear as the most stable defects in highly supersaturated samples. We have calculated the formation energies of both types of dislocation loops and found that, for defects of the same size, FDLs are more energetically stable than PDLs, if their diameter is smaller than 80 nm and viceversa. The application of these calculations to the samples studied in this work indicates that a direct correspondence exists between the formation energy of the two defect families and the number of atoms bound to them. Moreover, we have shown that the relative stability of FDLs and PDLs depends on the initial supersaturation of Si(int)s created during the implantation process.

Formation energies and relative stability of perfect and faulted dislocation loops in silicon

2000 ◽  
Vol 87 (12) ◽  
pp. 8420-8428 ◽  
Author(s):  
F. Cristiano ◽  
J. Grisolia ◽  
B. Colombeau ◽  
M. Omri ◽  
B. de Mauduit ◽  
...  
Keyword(s):  
Relative Stability ◽  
Dislocation Loops ◽  
Formation Energies

Process of the One-Dimensional Motion of Small Interstitial-Type Dislocation Loops in Iron

2006 ◽  
Vol 512 ◽  
pp. 103-106 ◽  
Author(s):  
K. Arakawa ◽  
Hirotaro Mori
Keyword(s):  
Habit Plane ◽  
Dislocation Loops ◽  
Long Distance ◽  
One Dimensional ◽  
Large Loop ◽  
Transmission Electron ◽  
Perfect Dislocation ◽  
Motion Process ◽  
Type Dislocation ◽  
The One

Extensive simulations based on classical molecular dynamics have shown that small interstitial-type perfect dislocation loops in various metals and alloys have the structure of bundles of crowdions and a loop can easily makes the one-dimensional glide motion due to almost independent motion of crowdions in the loop. However, the experimental knowledge on the motion of loops is not enough. The present study dynamically examined the motion process of loops in pure iron under 1000 keV electron irradiation and thermal annealing by using transmission electron microscopy under which loops could move. Two types of loops were formed by irradiation. Loops of one type possessed the Burgers vector of 1/2<111> and the habit plane of {011}, and loops of the other type were <001> {001}. Loops of the former type made back-andforth glide motion and expansion towards the direction along their Burgers vectors when they were smaller than about a few-ten nanometers in diameter. This strongly suggests that these small 1/2<111> loops have the structure of the bundle of crowdions. Loops of the latter type only rarely moved less frequently when they were smaller than about the same size. When loops of two types grew larger than about 50 nm, the characteristics of the motion of loops changed drastically. Dislocation segments of each large loop made long-distance glide independently of their opposite segments, and the habit plane deviated from the original ones. This kind of motion means that selfinterstitial atoms at the central region of such large loops are no longer the crowdions.

Point defect generation during the oxidation of silicon

1978 ◽  
Vol 36 (1) ◽  
pp. 320-321
Author(s):  
J.A. Lambert ◽  
P.S. Dobson
Keyword(s):  
Thin Foil ◽  
Geometrical Factor ◽  
Dislocation Loops ◽  
Self Diffusion ◽  
Self Energy ◽  
Thin Foils ◽  
Perfect Dislocation ◽  
Interstitial Defects ◽  
Boron Ions ◽  
Image Position

The interstitial defects created during ion-implantation in silicon condense out during annealing to form extrinsically faulted Frank loops and perfect dislocation loops. The annealing behaviour of these defects has been investigated by annealing electron microscope thin foils. It was found that the loops shrink and eventually disappear after annealing in the temperature range 900-1020° C in vacuum. Figure 1a shows faulted and perfect loops after implanting with 10 15 boron ions cm-2 at 40kV and bulk annealing for 50 minutes in nitrogen at 950° C. The thin foil was then annealed for 30 minutes at 1000° C in vacuum and figure 1b shows that the loops have shrunk during this treatment.The loop shrinkage is caused by the diffusion of interstitial point defects from the loop to the surface and the driving force for this process is provided by the self energy of the loops. The rate of shrinkage is given bywhere A is a geometrical factor, Ds is the coefficient of self diffusion and ΔF is the change in the free energy of the loop per emitted interstitial.

Alpha-recoil damage in titanite (CaTiSiO5): Direct observation and annealing study using high resolution transmission electron microscopy

1991 ◽  
Vol 6 (3) ◽  
pp. 560-564 ◽  
Author(s):  
Gregory R. Lumpkin ◽  
Ray K. Eby ◽  
Rodney C. Ewing
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Intermediate Phase ◽  
Recovery Process ◽  
Outer Zone ◽  
Alpha Decay ◽  
Transmission Electron ◽  
Interstitial Defects ◽  
Annealing Study ◽  
Track Diameter

“Tracks” of alpha-recoil nuclei have been observed directly in titanite (CaTiSiO5). Recoil tracks in titanite are 4 to 6 nm in diameter and consist of a central aperiodic zone surrounded by a narrow (0–2 nm) outer zone that is essentially crystalline, but which exhibits modulated image contrast due to interstitial defects. Previous work has suggested that titanite is 2 to 3 times more sensitive to alpha-decay damage than other ceramic phases (e.g., zircon, ZrSiO4). We find, however, that track diameters in titanite are essentially the same as reported for other phases, including zircon (ZrSiO4), pyrochlore (NaCaTa2O6F), and zirconolite (CaZrTi2O7). An annealing study of titanite (300 to 700 °C, N2) shows a two-stage recovery process. Track diameter decreases at 400 °C. An intermediate phase develops at 500 °C, and nearly all tracks are epitaxially recrystallized. At 700 °C, all tracks and the intermediate phase are gone.

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.

Defects in ion implanted silicon

1978 ◽  
Vol 36 (1) ◽  
pp. 386-387
Author(s):  
J.A. Lambert ◽  
P.S. Dobson
Keyword(s):  
Defect Structure ◽  
Dislocation Loops ◽  
Frank Loop ◽  
Burgers Vector ◽  
Temperature Range ◽  
Perfect Dislocation ◽  
Contrast Analysis ◽  
Image Position ◽  
Ion Implanted

The defect structure of ion-implanted silicon, which has been annealed in the temperature range 800°C-1100°C, consists of extrinsic Frank faulted loops and perfect dislocation loops, together with‘rod like’ defects elongated along <110> directions. Various structures have been suggested for the elongated defects and it was argued that an extrinsically faulted Frank loop could undergo partial shear to yield an intrinsically faulted defect having a Burgers vector of 1/6 <411>.This defect has been observed in boron implanted silicon (1015 B+ cm-2 40KeV) and a detailed contrast analysis has confirmed the proposed structure.

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.

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