First principles study of electronic properties of gallium nitride nanowires grown along different crystal directions

The electronic properties of hydrogen-saturated GaN nanowires with different orientations and sizes are investigated using first principles calculations, and three types of nanowires oriented along the 0 0 1], 1 1 0] and 1 ?1 0] crystal directions are considered. The electronic properties of nanowires in all three directions are extremely similar. All the hydrogen-saturated GaN nanowires show semiconducting behavior with a direct band gap larger than that of bulk wurtzite GaN. Quantum confinement leads to a decrease in the band gap of the nanowires with increasing nanowire size. The 0 0 1]-oriented nanowires with hexagonal cross sections are energetically more favorable than the 1 0 0]- and 1 ?1 0]-oriented nanowires with triangular cross sections.