title: Real-time observation of FIB-created dots and ripples on GaAs.
abstract: We report a phenomenological study of Ga dots and ripples created by a focused ion beam (FIB) on the GaAs(001) surface. Real-time observation of dot diffusion and ripple formation was made possible by recording FIB movies. In the case of FIB irradiation with a 40 nA current of Ga(+) ions accelerated under 40 kV with an incidence angle of θ = 30°, increasing ion dose gives rise to three different regimes. In Regime 1, dots with lateral sizes in the range 50-460 nm are formed. Dots diffuse under continuous sputtering. In Regime 2, dots self-assemble into Bradley and Harper (BH) type ripples with a pseudo-period of λ = 1150 ± 25 nm. In Regime 3, ripples are eroded and the surface topology evolves into microplanes. In the case of normal incidence, FIB sputtering leads only to the formation of dots, without surface rippling.
authors.affiliation: Laboratory for Integrated Micro Mechatronic Systems/Centre National de la Recherche Scientifique (UMI 2820), Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan. Center for International Research on Micro Mechatronics, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
authors.forename: F
authors.initials: F
authors.lastname: Rose
authors.forename: H
authors.initials: H
authors.lastname: Fujita
authors.forename: H
authors.initials: H
authors.lastname: Kawakatsu