title: Self-regulated radius of spontaneously formed GaN nanowires in molecular beam epitaxy.
abstract: We investigate the axial and radial growth of GaN nanowires upon a variation of the Ga flux during molecular beam epitaxial growth. An increase in the Ga flux promotes radial growth without affecting the axial growth rate. In contrast, a decrease in the Ga flux reduces the axial growth rate without any change in the radius. These results are explained by a kinetic growth model that accounts for both the diffusion of Ga adatoms along the side facets toward the nanowire tip and the finite amount of active N available for the growth. The model explains the formation of a new equilibrium nanowire radius after increasing the Ga flux and provides an explanation for two well-known but so far not understood experimental facts: the necessity of effectively N-rich conditions for the spontaneous growth of GaN nanowires and the increase in nanowire radius with increasing III/V flux ratio.
authors.affiliation: Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany.
authors.forename: Sergio
authors.initials: S
authors.lastname: Fernández-Garrido
authors.forename: Vladimir M
authors.initials: VM
authors.lastname: Kaganer
authors.forename: Karl K
authors.initials: KK
authors.lastname: Sabelfeld
authors.forename: Tobias
authors.initials: T
authors.lastname: Gotschke
authors.forename: Javier
authors.initials: J
authors.lastname: Grandal
authors.forename: Enrique
authors.initials: E
authors.lastname: Calleja
authors.forename: Lutz
authors.initials: L
authors.lastname: Geelhaar
authors.forename: Oliver
authors.initials: O
authors.lastname: Brandt