The geometrical phase analysis was an efficient method to measure strain from high-resolution transmission electron microscopy images. Here it was shown that it could also be applied efficiently to high-resolution scanning transmission electron microscopic images, which had several advantages. Patterns in high-resolution scanning transmission electron microscopy did not change with thickness and chemical composition, thicker samples could be analysed and strain and composition could be simultaneously determined. In many situations, the distortions due to the scanning of the beam could be corrected. The strain fields around different threading dislocations in an AlInN layer were determined from plan view samples prepared by focussed ion beam. Experimental strain maps were compared to analytical calculations that take into account the strain field of dislocations and of the In segregation. Mixed type dislocations were always terminated by an inverse hexagonal pyramidal pit, at the sample surface. The edges of the inverse pyramid were indium-rich. The dislocation core was not situated at the centre of the inverse pyramid, which was indium-rich, but slightly shifted.

Measuring Strain on HR-STEM Images: Application to Threading Dislocations in Al0.8In0.2N. J.L.Rouvière, A.Mouti, P.Stadelmann: Journal of Physics: Conference Series, 2011, 326[1], 012022