title: Formation mechanisms of GaN nanowires grown by selective area growth homoepitaxy.
abstract: This work provides experimental evidence and theoretical explanations regarding the formation mechanisms of GaN nanowires grown by selective area growth on GaN-on-sapphire templates. The first growth stage, driven by selective area growth kinetics, consists of initial nucleation (along the nanohole inner periphery), coalescence onset and full coalescence, producing a single nanocrystal within each nanohole. In the second growth stage, driven by free-surface-energy minimization, the formed nanocrystal undergoes morphological evolution, exhibiting initial cylindrical-like shape, intermediate dodecagonal shape and a final, thermodynamically stable hexagonal shape. From this point on, the nanowire vertical growth proceeds while keeping the stable hexagonal form.
authors.affiliation: ISOM - ETSIT, Universidad Politécnica de Madrid Avda. Complutense s/n, 28040 Madrid, Spain.
authors.forename: Žarko
authors.initials: Ž
authors.lastname: Gačević
authors.forename: Daniel
authors.initials: D
authors.lastname: Gómez Sánchez
authors.forename: Enrique
authors.initials: E
authors.lastname: Calleja
keywords: GaN nanowires; formation mechanism; molecular beam epitaxy; morphological evolution; selective area growth