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Title: Scratching damage on silicon crystal slices
Author: El Deghaidy, Fathy Hassan Ali
ISNI:       0000 0001 3442 6497
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 1977
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Experiments were carried out of scratching silicon slices with near (111) orientation, in and directions, by using two types of diamond indenters, at room temperature. Scratches have been investigated by optical and scanning electron microscopy, and X-ray topography. It is found that the appearance of the scratch and the wide residual strain field detected by diffraction contrast are both anisotropic with respect to direction, but in opposite senses; maximum chipping and wear is associated with minimum width of strain field for scratches in or near [112], [211] and [121] and vice versa for [112], [211] and [121]. It is concluded from a study of the topographic contrast in different reflections that the long-range field of residual elastic strain is in plane strain compression, and is associated with a system of cracks observed by optical microscopy. Scratches annealed in the range of temperatures (800°C- 1200°C) were examined by X-ray topography. It is found that no dislocation movement is detected in intrinsic silicon slices. Dislocation loops generated from scratches on the surface of slices doped with antimony and phosphorus. The greatest extent of glide occurs from the wide strain field of [112] scratches and the least from the narrow strain field of [112] scratches. Complete loops, and half loops of 60° dislocations have Burgers vectors lying in the plane of the slice in directions were studied. Slip lines have been observed along traces of (111) planes. A new technique has been developed to determine the misorientation angle from the (111) surface. A theoretical model of stress relaxation round a scratch is discussed. The results indicate that the activation energy for dislocation movement is ~ 0. 92 ev in the case of the [112] scratches, and ~ 1. 28 ev for [110] scratches. These figures agree roughly with the activation energies deduced from experiments in uniaxial tension on crystals orientated for single and double slip respectively. Growth features of metallic impurity were examined by (SEM) and (EPMA). Residual saw damage and contrast centres were observed by X-ray topography.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available