Atomistic modeling and HRTEM analysis of misfit dislocations in InN/GaN heterostructures

The enhanced structural mismatch of InN and GaN binary alloys leads in almost spontaneous formation of misfit dislocations (MDs) at the corresponding interfaces, thereby accommodating plastic relaxation. The open issue of the MD array in-plane configuration is addressed through a combination of high resolution transmission electron microscopy (HRTEM) observations with energetic mapping and HRTEM image simulation of InN/GaN interfaces extracted by atomistic modeling. Energetic mapping on the interfacial area of InN/GaN supercells relaxed by the Tersoff interatomic potential, designates that the MD arrays adopt image line directions and their Burgers vectors are image. HRTEM image simulations further reveal that the local arrangement of Moiré fringes observed in these interfaces depends strongly on the thickness of the TEM foil, thus resolving contradictory experimental reports. Geometric Phase Analysis on the simulated images justifies the results obtained by energetic mapping.