AVS 52nd International Symposium
    Nanometer-Scale Science and Technology Monday Sessions
       Session NS2-MoM

Paper NS2-MoM11
In Situ Resistance Measurement of Epitaxial Silicide Nanowires

Monday, October 31, 2005, 11:40 am, Room 210

Session: Nanowires
Presenter: P.A. Bennett, Arizona State University
Authors: H. Okino, University of Tokyo, Japan
R. Hobara, University of Tokyo, Japan
Y. Hosomura, University of Tokyo, Japan
I. Matsuda, University of Tokyo, Japan
S. Hasegawa, University of Tokyo, Japan
P.A. Bennett, Arizona State University
Correspondent: Click to Email
We present in situ resistance measurements for CoSi2 nanowires (NWs) on Si(110), using a custom-built multi-tip UHV-STM. We have shown elsewhere that self-assembled epitaxial silicide NWs can be formed with a variety of transition metals (Co, Ni, Fe, Ti, Pd, Dy) on Si(100), Si(111) or Si(110) surfaces, in various combinations (Phys. Rev. Lett v93, 2004, p256102). In most cases, these form via a new "endotaxial" growth mechanism, in which the silicide grows into the substrate along inclined Si{111} planes, breaking the symmetry of the surface and leading to the long, thin island shape. These NWs are metallic, single-crystal structures with potential applications as interconnects, nano-electrodes or as functional elements for nano-electronic devices. Four independent STM tips can be positioned to contact a single NW. Each tip is pushed ~ 10nm beyond the point of tunneling to make good electrical contact with the NW. Four-point measurements on a single NW yield typical values of 600 @ohm@ and 60 @ohm@ for the NW and contact resistance, respectively, for a NW with dimensions 60 nm wide, 40 nm high and 2 microns long. Similar values are obtained from a 2-point configuration by measuring the resistance vs. tip separation. The corresponding resistivity is @rho@ = 20-30 µ@ohm@cm, which is similar to that for high-quality epitaxial films of CoSi2 at 300K. This indicates that defect- and/or surface-scattering is small for these structures. We also find that the NWs are isolated from the substrate by a Schottky barrier with zero-bias resistance of ~ 10@super 7@ @ohm@. The good isolation results from a surface depletion layer near the NWs.