Local electronic structure of threading screw dislocation in wurtzite GaN

The atomic and electronic structure of the full-core threading screw dislocation in wurzite GaN has been investigated using a self-consistent density-functional tight-binding calculation. It is shown that the atoms are severely strained in a hexagonal atomic core, and an extra charge transfer of 0.1...

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Bibliographic Details
Published in:Computational materials science 2006-09, Vol.37 (3), p.410-416
Main Authors: Belabbas, I., Belkhir, M.A., Lee, Y.H., Chen, J., Béré, A., Ruterana, P., Nouet, G.
Format: Article
Language:English
Subjects:
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Dislocation
Electron states
Electronic structure
Exact sciences and technology
GaN
Iii-v semiconductors
Impurity and defect levels
Physics
SCC-DFTB
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Summary:The atomic and electronic structure of the full-core threading screw dislocation in wurzite GaN has been investigated using a self-consistent density-functional tight-binding calculation. It is shown that the atoms are severely strained in a hexagonal atomic core, and an extra charge transfer of 0.12 e occurs at the core atoms from Ga to N, in addition to the typical charge transfer of 0.56 e for bulk GaN. Filled and unfilled gap states are found to be spread over the entire band gap. The p states of the core N-atom mostly contribute to the tail states of valence and conduction bands, whereas the deep levels are heavily localized at the Ga and N core atoms. The coexistence of acceptor and donor gap states in the vicinity of the screw dislocations could be an origin of the leakage currents observed in GaN-based devices.
ISSN:0927-0256
1879-0801
DOI:10.1016/j.commatsci.2005.11.002