Structural and optical properties of as-synthesized, Ga 2O 3-coated, and Al 2O 3-coated GaN nanowires

Abstract

Structural and optical properties of as-synthesized, Ga 2O 3-coated, and Al 2O 3-coated GaN nanowires are examined in this paper. GaN nanowires were synthesized by thermal evaporation of ball-milled GaN powders in an NH 3 atmosphere. The thermal annealing of the as-synthesized GaN nanowires in an argon atmosphere allows their surfaces to be oxidized, leading to the formation of 2 nm-thick Ga 2O 3 layers. For the oxidized GaN nanowires, the distances between the neighboring lattice planes are shortened, and an excitonic emission band is remarkably enhanced in intensity, compared with the as-synthesized GaN nanowires. In addition, the as-synthesized GaN nanowires were coated cylindrically with Al 2O 3 by atomic layer deposition technique. Our study suggests that the Al 2O 3-coating passivates some of surface states in the GaN nanowires.