Metal-insulator transition in Pt-C nanowires grown by focused-ion-beam- induced deposition

Fernandez-Pacheco, A. , De Teresa, J.M., Cordoba, R. and Ibarra, M.R. (2009) Metal-insulator transition in Pt-C nanowires grown by focused-ion-beam- induced deposition. Physical Review B, 79, 174204. (doi: 10.1103/PhysRevB.79.174204)

Abstract

We present a study of the transport properties of Pt-C nanowires created by focused-ion-beam (FIB)-induced deposition. By means of the measurement of the resistance while the deposit is being performed, we observe a progressive decrease in the nanowire resistivity with thickness, changing from 108 μΩ cm for thickness ∼20 nm to a lowest saturated value of 700 μΩ cm for thickness > 150 nm. Spectroscopy analysis indicates that this dependence on thickness is caused by a gradient in the metal-carbon ratio as the deposit is grown. We have fabricated nanowires in different ranges of resistivity and studied their conduction mechanism as a function of temperature. A metal-insulator transition as a function of the nanowire thickness is observed. The results will be discussed in terms of the Mott-Anderson theory for noncrystalline materials. An exponential decrease in the conductance with the electric field is found for the most resistive samples, a phenomenon understood by the theory of hopping in lightly doped semiconductors under strong electric fields. This work explains the important discrepancies found in the literature for Pt-C nanostructures grown by FIB and opens the possibility to tune the transport properties of this material by an appropriate selection of the growth parameters.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Fernandez-Pacheco, Dr Amalio
• Authors: Fernandez-Pacheco, A., De Teresa, J.M., Cordoba, R., and Ibarra, M.R.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Physical Review B
• Publisher: American Physical Society
• ISSN: 2469-9950