Dislocation structure in AlN films induced by in situ transmission electron microscope nanoindentation

To elucidate dislocation generation and propagation processes in AlN films containing a high density of grown-in threading dislocations (TDs), in situ nanoindentation (NI) was performed in a transmission electron microscope at room temperature. Dislocations with the Burgers vector b=1/3<12̄10> were introduced not only on the primary slip plane, i.e., the (0001) basal planes, but also on the { 101̄1} and { 101̄2} pyramidal planes. The results are explained by considering the distribution of the resolved shear stress. It was found that the dislocations induced by NI interact with grown-in TDs: (1) for the NI-induced dislocations on pyramidal planes, edge grown-in TDs induce cross slip to basal planes, and (2) for the NI-induced dislocations on basal planes, screw grown-in TDs prevent their propagation, while edge grown-in TDs do not.