First-principles study of narrow single-walled GaN nanotubes

Abstract

Structural and electronic properties of narrow single-walled GaN nanotubes with diameter from 0.30 to 0.55 nm are investigated using the density functional method with generalized-gradient approximation. The calculations of total energies predict that the most likely GaN nanotubes in our calculation are ( 2 , 2 ) , ( 3 , 2 ) and ( 3 , 3 ) nanotubes. From a detailed analysis we find that these narrow single-walled GaN nanotubes are all semiconductors, of which the armchair and chiral tubes are indirect-band-gap semiconductors whereas the zigzag ones have a direct gap except for ( 4 , 0 ) tube. The indirect band gap of ( 4 , 0 ) tube can stem from band sequence change induced by curvature effect. Our results show that the π– π hybridization effect and the formation of benign buckling separations play a key role in the band sequence changes of ( 4 , 0 ) tube.