title: Droplet-Confined Alternate Pulsed Epitaxy of GaAs Nanowires on Si Substrates down to CMOS-Compatible Temperatures.
abstract: We introduce droplet-confined alternate pulsed epitaxy for the self-catalyzed growth of GaAs nanowires on Si(111) substrates in the temperature range from 550 °C down to 450 °C. This unconventional growth mode is a modification of the migration-enhanced epitaxy, where alternating pulses of Ga and As4 are employed instead of a continuous supply. The enhancement of the diffusion length of Ga adatoms on the {11̅0} nanowire sidewalls allows for their targeted delivery to the Ga droplets at the top of the nanowires and, thus, for a highly directional growth along the nanowire axis even at temperatures as low as 450 °C. We demonstrate that the axial growth can be simply and abruptly interrupted at any time without the formation of any defects, whereas the growth rate can be controlled with high accuracy down to the monolayer scale, being limited only by the stochastic nature of nucleation. Taking advantage of these unique possibilities, we were able to probe and describe quantitatively the population dynamics of As inside the Ga droplets in specially designed experiments. After all, our growth method combines all necessary elements for precise growth control, in-depth investigation of the growth mechanisms and compatibility with fully processed Si-CMOS substrates.
authors.affiliation: Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf , DE 01328 Dresden, Germany.|cfaed, Technische Universität Dresden , DE 01062 Dresden, Germany.
authors.forename: Leila
authors.initials: L
authors.lastname: Balaghi
authors.affiliation: Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf , DE 01328 Dresden, Germany.|cfaed, Technische Universität Dresden , DE 01062 Dresden, Germany.
authors.forename: Tina
authors.initials: T
authors.lastname: Tauchnitz
authors.affiliation: Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf , DE 01328 Dresden, Germany.
authors.forename: René
authors.initials: R
authors.lastname: Hübner
authors.affiliation: Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf , DE 01328 Dresden, Germany.
authors.forename: Lothar
authors.initials: L
authors.lastname: Bischoff
authors.affiliation: Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf , DE 01328 Dresden, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Schneider
authors.affiliation: Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf , DE 01328 Dresden, Germany.|cfaed, Technische Universität Dresden , DE 01062 Dresden, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Helm
authors.affiliation: Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf , DE 01328 Dresden, Germany.
authors.forename: Emmanouil
authors.initials: E
authors.lastname: Dimakis
keywords: GaAs; Si substrate; nanowire; pulsed epitaxy; self-catalyzed