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Impact of Rotational Twin Boundaries and Lattice Mismatch on III–V Nanowire Growth

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journal contribution
posted on 07.09.2017, 00:00 by Matthias Steidl, Christian Koppka, Lars Winterfeld, Katharina Peh, Beatriz Galiana, Oliver Supplie, Peter Kleinschmidt, Erich Runge, Thomas Hannappel
Pseudomorphic planar III–V transition layers greatly facilitate the epitaxial integration of vapor–liquid–solid grown III–V nanowires (NW) on Si(111) substrates. Heteroepitaxial (111) layer growth, however, is commonly accompanied by the formation of rotational twins. We find that rotational twin boundaries (RTBs), which intersect the surface of GaP/Si(111) heterosubstrates, generally cause horizontal NW growth and may even suppress NW growth entirely. Away from RTBs, the NW growth direction switches from horizontal to vertical in the case of homoepitaxial GaP NWs, whereas heteroepitaxial GaAs NWs continue growing horizontally. To understand this rich phenomenology, we develop a model based on classical nucleation theory. Independent of the occurrence of RTBs and specific transition layers, our model can generally explain the prevalent observation of horizontal III–V NW growth in lattice mismatched systems and the high crystal quality of horizontal nanowires.