Observation Of Dislocation Motion Research Articles

Column-by-column observation of dislocation motion in CdTe: Dynamic scanning transmission electron microscopy

The dynamics of partial dislocations in CdTe have been observed at the atomic scale using aberration-corrected scanning transmission electron microscopy (STEM), allowing the mobility of different dislocations to be directly compared: Cd-core Shockley partial dislocations are more mobile than Te-core partials, and dislocation cores with unpaired columns have higher mobility than those without unpaired columns. The dynamic imaging also provides insight into the process by which the dislocations glide. Dislocations with dangling bonds on unpaired columns are found to be more mobile because the dangling bonds mediate the bond exchanges required for the dislocations to move. Furthermore, a screw dislocation has been resolved to dissociate into a Shockley partial-dislocation pair along two different directions, revealing a way for the screw dislocation to glide in the material. The results show that dynamic STEM imaging has the potential to uncover the details of dislocation motion not easily accessible by other means.

In situ transmission electron microscopy observation of dislocation motion in 9Cr steel at elevated temperatures: influence of shear stress on dislocation behavior.

To elucidate high-temperature plastic deformation (creep) mechanism in materials, it is essential to observe dislocation motion under tensile loading. There are many reports on in situ transmission electron microscopy (TEM) observations in the literature; however, the relationship between the dislocation motion and shear stress in 9Cr steel is still not clear. In this study, in order to evaluate this relationship quantitatively, in situ TEM observations were carried out in conjunction with finite element method (FEM) analysis. A tensile test sample was strained at an elevated temperature (903 K) inside a transmission electron microscope, and the stress distribution in the strained sample was analyzed by FEM. The dislocation behavior was clearly found to depend on the shear stress. At a shear stress of 66 MPa, both the dislocation velocity and mobile dislocation density were low. However, a high shear stress level of 95 MPa caused a noticeable increase in the dislocation velocity and mobile dislocation density. Furthermore, in this article, we discuss the dependence of the dislocation behavior on stress. The results presented here also indicate that the relationship between the microstructure and the strength of materials can be revealed by the methods used in this work.

Observation of Dislocation Motion in Si1-xGex Thin Film on Si Substrate by Laser Scattering Method

In this study, we observed a misfit (MS) dislocation in a SiGe film on a Si substrate (SiGe/Si) by laser scattering, which is a nondestructive method; furthermore, using this technique, we determined the velocity of a threading (TH) dislocation in a 56-nm-thick Si0.76Ge0.24 film over a wide temperature range. It was found that the TH dislocation velocity is described by an Arrhenius plot with an activation energy of 1.9 eV. The TH dislocation velocity at 375 °C is observed on the extrapolation of the Arrhenius plots obtained in the high-temperature region; this indicates that the TH dislocation motion in a Si0.76Ge0.24 film is thermally activated at this low temperature. It was also clarified that this technique is effective for regions with a high density of MS dislocations.

In-situ observation of dislocation motion in icosahedral Al–Pd–Mn quasicrystals

Dislocation motion in icosahedral Al–Pd–Mn quasicrystals has been observed in situ in a transmission electron microscope between 700 and 750°C. Contrast analyses show that it takes place by pure climb in twofold, threefold and fivefold planes. Moving dislocations exhibit polygonal shapes with edges parallel to twofold directions, in agreement with a difficult jog-pair nucleation. Dislocation multiplication, annihilation and local pinning are described and discussed, as well as the role of the phason faults trailed in the wake of dislocations, at the lowest investigated temperatures.

827 薄膜の真性応力に起因するシリコン基板中の転位の動力学的解析

In semiconductor devices, it is known that electrical failures are caused by the dislocation. But observation of dislocation motion in the micro-scale devices is very difficult. Therefore, it is useful for searching the source of dislocation if we can simulate the dislocation movement. In this paper, we have developed dislocation simulator and apply to the stress field caused by the intrinsic stress of the silicon-nitride thin film. We can reproduce the dependence of the dislocation generation on the temperature qualitatively.

In Situ Observations of Dislocation Motion in Polycrystalline Silicon during Straining Experiment in a High-Voltage Electron Microscope

In Situ Observations of Dislocation Motion in Polycrystalline Silicon during Straining Experiment in a High-Voltage Electron Microscope

Transients occurring during stress dip experiments on creep of an Al-0.3wt.%Li alloy at 473 K

Both unloading and reloading experiments were performed on an Al-0.3wt.%Li alloy crept at 473 K. Large anelastic instantaneous strains occur on both unloading and reloading. The reloading strains depend on the time of unloading and the stress reduction and support the internal stress model of creep. The results are discussed in terms of observations of dislocation motion in pure aluminium and aluminium alloys.

Observation of dislocation motion in CdS by transmission electron microscopy

Observation of dislocation motion in CdS by transmission electron microscopy

Direct observation of dislocation motion in ZnO

Direct observation of dislocation motion in ZnO

Observations of Dislocation Motion by Etch Hillocks in White Tin Single Crystals

Pyramidal etch hillocks are produced on the {001} surfaces of 99.999% pure white tin single crystals at the sites of both fresh and aged dislocations with the highly selective etchant. Hillocks grow with a constant rate during the etching period. The growth rate of the edge length of a hillock is about 2.1×10-2 µ/sec. When the crystals are strained in the etchant, etch traces of hillocks are produced just along the loci of the moving dislocations. In this case, various modes of dislocation motion can be discriminated in moving direction, velocity and its variation from the appearances of traces.