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A. Lugstein, A. M. Andrews, M. Steinmair, Y.J. Hyun, E. Bertagnolli, M. Weil, P. Pongratz, M. Schramböck, T. Roch, G. Strasser:
"Growth of branched single-crystalline GaAs whiskers on Si nanowire trunks";
Nanotechnology, 18 (2007), 355306-1 - 355306-5.

In this paper we present the hetero-epitaxial growth of single-crystalline GaAs whiskers on Si(111)-nanowire trunks forming hierarchical star-like structures with a six-fold symmetry. These hierarchical nanostructures have been successfully formed utilizing both vapor-liquid-solid (VLS) growth by low-pressure chemical vapor deposition (LPCVD) and molecular-beam epitaxy (MBE) techniques. High-resolution transmission electron microscopy (HRTEM) studies revealed the [111] growth direction of the core Si nanowires (Si-NWs) with six {112} facet planes. The sequentially grown branches are single-crystalline hexagonal GaAs nanowhiskers which grow preferably in the [0001] direction and are perpendicular to the {112} facets of the Si-NW backbone. Photoluminescence (PL) measurements confirm the good crystalline quality of the GaAs nanowhiskers and a blueshift of about 30 meV compared to bulk zinc blende-type GaAs. The ability to prepare rotationally branched NW structures should open new opportunities for both fundamental research and applications including monolithic three-dimensional nanoelectronics and nanophotonics.

http://dx.doi.org/10.1088/0957-4484/18/35/355306

http://www.iop.org/EJ/abstract/0957-4484/18/35/355306