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Compressive strain formation in surface‐damaged crystals
Author(s) -
Ferrari Claudio,
Beretta Sara,
Rotunno Enzo,
Korytár Dusan,
Zaprazny Zdenko
Publication year - 2020
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576720003702
Subject(s) - materials science , dislocation , crystal (programming language) , wafer , strain (injury) , transmission electron microscopy , burgers vector , surface (topology) , crystallography , composite material , geometry , chemistry , nanotechnology , medicine , mathematics , computer science , programming language
The mechanism of formation of residual strain in crystals with a damaged surface has been studied by transmission electron microscopy in GaAs wafers ground with sandpaper. The samples showed a dislocation network located near the sample surface penetrating to a depth of a few micrometres, comparable to the size of abrasive particles used for the treatment, and no other types of defects were observed. A simple model for the formation of a compressive strain induced by the dislocation network in the damaged layer is proposed, in satisfactory agreement with the measured strain. The strain is generated by the formation of dislocation half‐loops at the crystal surface, having the same component of the Burgers vectors parallel to the surface of the crystal. This is equivalent to the insertion of extra half‐planes from the crystal surface to the depth of the damaged zone. This model can be generalized for other crystal structures. An approximate calculation of the strain generated from the observed dislocation distribution in the sample agrees with the proposed model and permits the conclusion that this mechanism is in general sufficient to explain the observed compressive strain, without the need to consider other types of defects.