Tuneable anisotropic transport in nitrogen-doped nanocrystalline diamond films: Evidence of a graphite-diamond hybrid superlattice

Nano-Scale Transport Physics Laboratory, School of Physics, University of the Witwatersrand Private Bag 3, WITS 2050, Johannesburg, South Africa

^(a) Somnath.Bhattacharyya@wits.ac.za

Received: 1 August 2012
Accepted: 26 November 2012

Abstract

We show strong evidence of superlattice-like carbon layered structures in heavily nitrogen-doped ultrananocrystalline diamond (UNCD) films through the experimental demonstration of temperature-dependent anisotropic diffusive transport. The superlattice periodicity, in the range of several nanometers, is derived from the analysis of both magneto-resistance and the temperature-dependent conductivity based on the generalized diffusive Fermi surface model. The effect of quasi–two-dimensionality on the magneto-transport of these films yields a weak temperature dependence of the electron dephasing length. These results explain a reasonably strong coupling between the conducting carbon layers separated by the insulating nanodiamond grains producing the anisotropic transport in UNCD films controlled by the level of nitrogen incorporation.