•Daniel Secker, Ralph Krupke und Heiko B. Weber
Forschungszentrum Karlsruhe, Institut für Nanotechnologie, Postfach 3640, D-76021 Karlsruhe

A combination of dielectrophoresis and shadow evaporation has been used to encapsulate the ends of single-walled carbon nanotubes (SWNT) by metallic leads. For the shadow evaporation of the metallic leads a mask of Si₃N₄ was prepared by standard e-beam lithography on a PMMA/Si₃N₄/SiO₂/Si substrate using successive etch steps with SF₆ and HF [1]. After the first shadow evaporation, SWNTs were selectively deposited from a DMF suspension between the contacts using alternating electric fields [2]. A second shadow evaporation step fully encapsulates the ends of the SWNTs by the metallic leads. This protocol avoids any exposure of the SWNTs with organic substances in contrast to marker-assisted e-beam lithography. This technique has been developed to study the influence of the contacts and the chemical environments on the electric transport.