Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 2: Transport: Nanoelectronics I - Quantum Dots and Wires, Point Contacts 1
TT 2.2: Vortrag
Montag, 23. März 2009, 10:30–10:45, HSZ 301
Scanning probe measurements and electromigration of metallic nanostructures under ultra-high vacuum conditions — •Dominik Stöffler1, Shawn Fostner2, Hilbert v. Löhneysen1,3, Peter Grütter2, and Regina Hoffmann1 — 1Physikalisches Institut and DFG Center for Functional Nanostructures (CFN), Universität Karlsruhe, D-76128 Karlsruhe, Germany — 2Physics Department, McGill university, H3A-2T8 Montreal, Canada — 3Forschungszentrum Karlsruhe, Institut für Festkörperphysik, D-76021 Karlsruhe, Germany
Quantum effects play an important role in metal contacts of nanometer size. We use e-beam litho-graphy as well as shadow evaporation through a stencil mask to fabricate nanobridges made of gold and platinum. The bridges are subject to feedback-controlled electromigration in ultra-high vacuum (UHV). While investigating the e-beam fabricated platinum structures with the scanning tunneling microscope (STM) in UHV we discovered dense topographically higher features in regions of anteceding STM scans, suggesting deposition of additional material, possibly carbon, of up to 10 nm thickness. We imaged these regions with STM as well as with scanning electron microscopy (SEM). To avoid such a deposition on the metallic bridges we used atomic force microscopy to investigate the electromigration in UHV. The gold wires show no fundamental difference to electromigration under ambient conditions. Platinum wires need a higher voltage to start the electromigraton process compared to gold wires. We have obtained images with 3 nm resolution and have observed conductance plateaus related to the atomic structure of the resulting gold nanocontacts.