An investigation was made of gallium and nitrogen vacancies in gallium nitride (GaN) bulk and nanowires using self-interaction corrected pseudopotentials (SIC). The band structures were examined in order to compare and contrast differences between the SIC results and standard density functional theory (DFT) results using a generalized gradient approximation (GGA) functional. For pure nanowires, similar trends in the band-gap behaviour were observed, with the gap decreasing for increasing nanowire diameters (with larger band-gaps using SIC pseudopotentials). For gallium vacancies in bulk GaN and GaN nanowires, SIC results were similar to DFT-GGA results, but with larger band-gaps. Nitrogen vacancies in bulk GaN show similar defect-induced states near the conduction band, whilst a lower lying defect state was observed below the valence band for the DFT-GGA calculations and above the valence band for the SIC results. For nitrogen vacancies in GaN nanowires, similar defect states were observed near to the conduction band. However, while the SIC calculations also revealed defect state(s) above the valence band, it was not possible to locate this state for the DFT-GGA calculations (perhaps because it was hybridized with edge states and buried below the valence band).

Vacancies in GaN Bulk and Nanowires: Effect of Self-Interaction Corrections. D.J.Carter, M.Fuchs, C.Stampfl: Journal of Physics - Condensed Matter, 2012, 24[25], 255801