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.

scholarly journals Microstructure Evolution in He-Implanted Si at 600 °C Followed by 1000 °C Annealing

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5107
Author(s):  
Zhen Yang ◽  
Zhiping Zou ◽  
Zeyang Zhang ◽  
Yubo Xing ◽  
Tao Wang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Single Crystal ◽  
Microstructure Evolution ◽  
Cavity Growth ◽  
Stacking Fault ◽  
Structural Defects ◽  
Dislocation Loops ◽  
Transmission Electron

Si single crystal was implanted with 230 keV He+ ions to a fluence of 5 × 1016/cm2 at 600 °C. The structural defects in Si implanted with He at 600 °C and then annealed at 1000 °C were investigated by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The microstructure of an as-implanted sample is provided for comparison. After annealing, rod-like defects were diminished, while tangled dislocations and large dislocation loops appeared. Dislocation lines trapped by cavities were directly observed. The cavities remained stable except for a transition of shape, from octahedron to tetrakaidecahedron. Stacking-fault tetrahedrons were found simultaneously. Cavity growth was independent of dislocations. The evolution of observed lattice defects is discussed.

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.

Structural Defects in Laser Annealed Arsenic Implanted Silicon

1990 ◽  
Vol 209 ◽  
Author(s):  
J. M. Tonnerre ◽  
M. Matsuura ◽  
G. S. Cargill III ◽  
L. W. Hobbs
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Defects ◽  
Dislocation Loops ◽  
Double Crystal ◽  
Rocking Curve ◽  
X Ray ◽  
Positive Strain ◽  
Transmission Electron ◽  
Heavily Doped

ABSTRACTLaser annealed arsenic implanted silicon specimens with doses ranging from 6×1015 to 7×1016 As/cm 2 have been investigated by transmission electron microscopy (TEM) and double crystal xray diffractometry (DCD). For the highest implant dose, laser powers ranging from 1.1 to 2.2 J/cm 2 have been used. Experimental observations show two new features for this kind of specimen. First, in some cases, TEM micrographs evidence small (˜50Å diameter) precipitate-like defects and/or dislocation loops confined within the heavily doped region. Second, in some cases, DCD shows a positive strain in addition to the negative strain attributed to 90% As in substitutional sites. X-ray rocking-curve simulations reveal that the negative strain drops to zero around 1000Å before the end of the As distribution. This might be related to the presence of Si interstitials in the deepest region of the As distribution.

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.

Dechannealing Study of Nanocrystalline Si:H Layers Produced by High Dose Hydrogen Irradiation of Silicon Crystals

1998 ◽  
Vol 536 ◽  
Author(s):  
V. P. Popov ◽  
A. K. Gutakovsky ◽  
I. V. Antonova ◽  
K. S. Zhuravlev ◽  
E. V. Spesivtsev ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Rutherford Backscattering Spectrometry ◽  
Nanocrystalline Structure ◽  
Structural Defects ◽  
High Dose ◽  
Silicon Crystals ◽  
Strong Energy ◽  
Transmission Electron ◽  
Hydrogen Implantation

AbstractA study of Si:H layers formed by high dose hydrogen implantation (up to 3x107cm-2) using pulsed beams with mean currents up 40 mA/cm2 was carried out in the present work. The Rutherford backscattering spectrometry (RBS), channeling of He ions, and transmission electron microscopy (TEM) were used to study the implanted silicon, and to identify the structural defects (a-Si islands and nanocrystallites). Implantation regimes used in this work lead to creation of the layers, which contain hydrogen concentrations higher than 15 at.% as well as the high defect concentrations. As a result, the nano- and microcavities that are created in the silicon fill with hydrogen. Annealing of this silicon removes the radiation defects and leads to a nanocrystalline structure of implanted layer. A strong energy dependence of dechanneling, connected with formation of quasi nanocrystallites, which have mutual small angle disorientation (<1.50), was found after moderate annealing in the range 200-500°C. The nanocrystalline regions are in the range of 2-4 nm were estimated on the basis of the suggested dechanneling model and transmission electron microscopy (TEM) measurements. Correlation between spectroscopic ellipsometry, visible photoluminescence, and sizes of nanocrystallites in hydrogenated nc-Si:H is observed.

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.

Citrate Stabilized Silver Nanoparticles

2011 ◽  
Vol 3 (3) ◽  
pp. 15-28 ◽  
Author(s):  
Nabraj Bhattarai ◽  
Subarna Khanal ◽  
Pushpa Raj Pudasaini ◽  
Shanna Pahl ◽  
Dulce Romero-Urbina
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silver Nanoparticles ◽  
Zeta Potential ◽  
Colloidal Solution ◽  
Measurement Techniques ◽  
Structural Defects ◽  
Potential Measurement ◽  
Transmission Electron

Citrate stabilized silver (Ag) colloidal solution were synthesized and characterized for crystallographic and surface properties by using transmission electron microscopy (TEM) and zeta potential measurement techniques. TEM investigation depicted the size of Ago ranges from 5 to 50 nm with smaller particles having single crystal structure while larger particles with structural defects (such as multiply twinned, high coalescence and Moire patterns). ?-potential measurement confirms the presence of Ag+ in nAg stock solution. The shift in ?-potential measurement by +25.1 mV in the filtered solution suggests the presence of Ag+ in Ago nanoparticles.

Formation of Excess Donors During High-Dose 74Ge+ Ion Implantation

1994 ◽  
Vol 354 ◽  
Author(s):  
Z. Xia ◽  
E. Ristolainen ◽  
R. Elliman ◽  
H. Ronkainen ◽  
S. Eränen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Defects ◽  
High Dose ◽  
Donor Concentration ◽  
Materials Analysis ◽  
Si Substrates ◽  
Transmission Electron ◽  
Activation Annealing ◽  
Secondary Ion

AbstractRecently observations that high-dose Ge implantations into Si substrates caused the n-type carrier concentration to increase were attributed to residual structural defects after activation annealing [7,12]. However, co-implantation of an n-type impurity is another possibility. The origin of this excess donor concentration has been studied in this work. The possibilities of residual defects versus implantation of impurities have been investigated using two different implanters and materials analysis. Comparison of data from different implanters showed that the concentration of excess donors was sensitive to the implanter configuration. Furthermore, transmission electron microscopy (TEM), Rutherford backscattering channeling (RBS-C), and spreading resistance profiling (SRP) data showed that the excess donor effect was related to impurities rather than residual defects. Secondary-ion mass spectroscopy (SIMS) and SRP measurements confirmed that impurities such as 75As ions were present after implants. This impurity easily explains the excess donor concentration when 75Ge implants are performed into silicon wafers doped with phosphorous.

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