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Title: Abrasion damage on near (111) silicon slices
Author: Shahid, Mohammed Afzal
ISNI:       0000 0001 3396 0268
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 1977
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The process of abrasion and indentation and associated residual surface damage have been studied on near (111) silicon as a function of load and direction of abrasion. It has been shown that at very low loads on the Vickers diamond microhardness indenter, the damage is produced in a thin surface layer by the nucleation of dislocations only. Heavier indenter loads initiate cracks which ultimately lead to the process of chipping. The occurrence of chipping has been found to be dependent on the scratching direction, with a strong sense effect in - directions. A [112] scratch has been found to be heavily chipped while the corresponding [112]- scratch is bounded by chevron cracks only. Scanning electron microscopy has shown the clayey nature of material in the central parts of sharply cut regions round the chip cavities that have irregularly curved surface traces. X-ray topography has been used to analyse the nature of the large residual stress round the scratches. The sense effect in - scratches shows wider topographic contrast round a [112]- scratch than the heavily chipped [112]- scratch. No sense effect has been found in - scratches. Long range dislocation glide takes place when the substrates with the surface damage are annealed in the temperature range used for the device processing. The sense effect between the - scratches is found to persist even after heat-treatment. The [112]- scratches emit dislocation half loops gliding on (111) while - scratches emit dislocation loop segments intersecting the free surface and gliding on inclined slip planes. X-ray topography and transmission electron microscopy have been used. to characterise these dislocations. A simple dislocation model has been proposed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available