title: Crystallographic Mapping of Guided Nanowires by Second Harmonic Generation Polarimetry.
abstract: The growth of horizontal nanowires (NWs) guided by epitaxial and graphoepitaxial relations with the substrate is becoming increasingly attractive owing to the possibility of controlling their position, direction, and crystallographic orientation. In guided NWs, as opposed to the extensively characterized vertically grown NWs, there is an increasing need for understanding the relation between structure and properties, specifically the role of the epitaxial relation with the substrate. Furthermore, the uniformity of crystallographic orientation along guided NWs and over the substrate has yet to be checked. Here we perform highly sensitive second harmonic generation (SHG) polarimetry of polar and nonpolar guided ZnO NWs grown on R-plane and M-plane sapphire. We optically map large areas on the substrate in a nondestructive way and find that the crystallographic orientations of the guided NWs are highly selective and specific for each growth direction with respect to the substrate lattice. In addition, we perform SHG polarimetry along individual NWs and find that the crystallographic orientation is preserved along the NW in both polar and nonpolar NWs. While polar NWs show highly uniform SHG along their axis, nonpolar NWs show a significant change in the local nonlinear susceptibility along a few micrometers, reflected in a reduction of 40% in the ratio of the SHG along different crystal axes. We suggest that these differences may be related to strain accumulation along the nonpolar wires. We find SHG polarimetry to be a powerful tool to study both selectivity and uniformity of crystallographic orientations of guided NWs with different epitaxial relations.
authors.affiliation: Departments of Physics of Complex Systems and ‡Materials and Interfaces and §Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Lior
authors.identifier: 0000-0002-7165-8913
authors.initials: L
authors.lastname: Neeman
authors.affiliation: Departments of Physics of Complex Systems and ‡Materials and Interfaces and §Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Regev
authors.initials: R
authors.lastname: Ben-Zvi
authors.affiliation: Departments of Physics of Complex Systems and ‡Materials and Interfaces and §Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Katya
authors.initials: K
authors.lastname: Rechav
authors.affiliation: Departments of Physics of Complex Systems and ‡Materials and Interfaces and §Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Ronit
authors.initials: R
authors.lastname: Popovitz-Biro
authors.affiliation: Departments of Physics of Complex Systems and ‡Materials and Interfaces and §Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Dan
authors.initials: D
authors.lastname: Oron
authors.affiliation: Departments of Physics of Complex Systems and ‡Materials and Interfaces and §Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Ernesto
authors.identifier: 0000-0002-9919-0734
authors.initials: E
authors.lastname: Joselevich
keywords: Guided nanowires; polarimetry; second harmonic generation; strain; zinc oxide