Structure and electrical properties of [0001] GaN nanowires

We perform density functional theory within the generalized gradient approximation to investigate infinitely wurtzite bare GaN nanowires in the [0001] direction. We report atomic and electronic structure of GaN nanowires with diameters of 10 and 16 Å. We find that relaxations on the facets are very similar to the ones in nonpolar (10-10) surfaces and play an important role in stabilizing the wires, and the average Ga-N bond length of the GaN nanowires decreases compared with bulk GaN. Both wires are found to be semiconducting and have a direct gap, with band gaps slightly smaller than that in bulk GaN. The shape of the band edge remains unaltered as the size of the nanowire increases. It is also found, for Ga and N atoms at the edge of the nanowires, the Ga 3p predominantly contribute to the edge states near the conduction band minimum, while the N 2p contribute mainly to the edge states near the valence band maximum. The present calculated results are helpful to gain a systematic understanding of structure, electrical properties of wurtzite GaN nanowires.

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