Nano-indentations were made on the (001) surfaces of single crystals at room temperature, and were observed using transmission electron microscopy. The permanent deformation which was produced by a Berkovitch indentor, at maximum loads ranging from 600 to 1700μN, was analyzed. The plastic zone size was measured as a function of the maximum load, in order to determine the yield strength at room temperature. The fine structure of the dislocations which were generated was analyzed, and was compared with previously reported structures for high indentation loads. Long perfect dislocation lines were observed to extend in both <110> directions. A characteristic bowing at the end of the lines was observed; changing screw dislocations to 60º-type. Their Burgers vectors were parallel to the (001) sample surface and were directed along the extension direction. The results were in good agreement with observations which had been made using higher indentation loads. A few stacking faults were observed where perfect b = (a/2)[¯110] dislocations were extended. They represented the first steps towards micro-twin formation.

Transmission Electron Microscopy Observations of Low-Load Indents in GaAs E.Le Bourhis, G.Patriarche: Philosophical Magazine Letters, 1999, 79[10], 805-12