SKM 2021 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 1: Thin Film Properties

DS 1.2: Vortrag

Montag, 27. September 2021, 10:15–10:30, H3

Stacking fault fold and step junctions as nucleation sites of threading dislocations in III-nitride films — •Georgios Dimitrakopulos¹, Isaak Vasileiadis¹, Joanna Moneta², Polyxeni Chatzopoulou¹, Philomela Komninou¹, and Julita Smalc-Koziorowska² — ¹Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece — ²Institute of High Pressure Physics, Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland

III-nitride semiconductor heterostructures have been employed with great success in optoelectronic and electronic devices despite the high densities of threading dislocations (TDs) that they contain. In order to unlock the full potential of these materials, it is imperative to diminish the TD nucleation sites. We present a mechanism of TD nucleation taking place at folds and steps of basal stacking faults (BSFs), particularly intrinsic I1 BSFs, that are frequent in (0001) epilayers due to their low self-energy. In-depth analysis by transmission electron microscopy (TEM) revealed that TD introduction is geometrically necessary at nodes of Shockley-like partial dislocations (PDs) at such BSFs. These PDs have the same Burgers vectors as normal Shockley PDs but exist only at junctions of the two variants of the BSF stacking sequence. In I1 BSF overlaps, the introduction of Frank-Shockley PDs is avoided, thus eliminating the elastic strain along the growth direction. Overlapped BSFs were observed to form hexagonal closed domains in which the coexistence of PD segments makes TD nucleation energetically favorable.