Plastic deformation modes of gallium arsenide in nanoindentationand nanoscratching

The mechanical deformation by nanoindentation and scratching of gallium arsenide has been investigated using cross-sectional transmission electron microscopy. Twinning was found to be the main deformation process occurring during indentation while only slip bands and perfect dislocations are observed during scratching. This behavior is explained, in the authors' experiments, with the strain rate in scratching being hundred times greater than in indentation. Hence, the low indentation velocity allows twins to be nucleated and propagated from surface inhomogeneities, whereas in scratching, the deformation occurs first in front of the indenter and the scratching speed allows only perfect α dislocation to propagate.