title: Ga crystallization dynamics during annealing of self-assisted GaAs nanowires.
abstract: In As atmosphere, we analyzed the crystallization dynamics during post-growth annealing of Ga droplets residing at the top of self-assisted GaAs nanowires grown by molecular beam epitaxy. The final crystallization steps, fundamental to determining the top facet nanowire morphology, proceeded via a balance of Ga crystallization via vapor-liquid-solid and layer-by-layer growth around the droplet, promoted by Ga diffusion out of the droplet perimeter, As desorption, and diffusion dynamics. By controlling As flux and substrate temperature the transformation of Ga droplets into nanowire segments with a top surface flat and parallel to the substrate was achieved, thus opening the possibility to realize atomically sharp vertical heterostructures in III-As self-assisted nanowires through group III exchange.
authors.affiliation: LNESS and Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Milano, Italy.
authors.forename: David
authors.initials: D
authors.lastname: Scarpellini
authors.forename: Alexey
authors.initials: A
authors.lastname: Fedorov
authors.forename: Claudio
authors.initials: C
authors.lastname: Somaschini
authors.forename: Cesare
authors.initials: C
authors.lastname: Frigeri
authors.forename: Monica
authors.initials: M
authors.lastname: Bollani
authors.forename: Sergio
authors.initials: S
authors.lastname: Bietti
authors.forename: Richard
authors.initials: R
authors.lastname: Nöetzel
authors.forename: Stefano
authors.initials: S
authors.lastname: Sanguinetti