Structural and electronic properties of a-edge dislocations along < 1-100 > in GaN

S Giaremis and P Komninou and I Belabbas and J Chen and J Kioseoglou, JOURNAL OF APPLIED PHYSICS, 123, 244301 (2018).

DOI: 10.1063/1.5034198

Computational analysis via molecular dynamics and density functional theory simulations elucidated the structural and electronic properties of a-type basal edge dislocations lying in the < 1-100 > direction in wurtzite GaN. As a particular and predominant type of misfit dislocations, experimentally identified in coherently grown semipolar heterostructures, understanding of their properties at the atomistic level is crucial for exploring the growth conditions of the material and improving its performance in its various applications. A total of six core configurations are revealed for the first time and investigated systematically. The energetic hierarchy of these core configurations and their electronic structures are determined. The two shuffle core configurations 3-1 and 4-2 are found to be energetically favorable with respect to the glide 2-2 core in both polarities. It is demonstrated that all the core configurations of the a-type basal dislocations introduce multiple gap states which leads to a narrowing of the bandgap in comparison to that of the pristine material, with the N-polar configurations having a more pronounced and detrimental impact. The presence of Ga-related dangling bonds in the vicinity of the core is widely observed, leading to a shift of the Fermi level to the related s orbitals. Published by AIP Publishing.

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