Anisotropic weakly localized transport in nitrogen-doped ultrananocrystalline diamond films

TL;DR

This study reveals anisotropic weak localization effects in nitrogen-doped ultrananocrystalline diamond films, showing unique 3D transport behavior influenced by electron-electron interactions and low-dimensional structures at low temperatures.

Contribution

It demonstrates the dominant role of anisotropic weak localization in 3D UNCD films and characterizes their unusual temperature-dependent transport properties and electronic structure.

Findings

Weak localization effects dominate conductivity corrections.

Electronic dephasing time follows a weak temperature dependence.

Transport behavior suggests low-dimensional superlattice structures.

Abstract

We establish the dominant effect of anisotropic weak localization (WL) in three dimensions associated with a propagative Fermi surface, on the conductivity correction in heavily nitrogen doped ultrananocrystalline diamond (UNCD) films based on magneto-resistance studies at low temperatures. Also, low temperature electrical conductivity can show weakly localized transport in 3D combined with the effect of electron-electron interactions in these materials, which is remarkably different from the conductivity in 2DWL or strong localization regime. The corresponding dephasing time of electronic wavefunctions in these systems described as ~ T^-p with p < 1, follows a relatively weak temperature dependence compared to the generally expected nature for bulk dirty metals having $p \geq 1$. The temperature dependence of Hall (electron) mobility together with an enhanced electron density has been used to interpret the unusual magneto-transport features and show delocalized electronic transport in these n-type UNCD films, which can be described as low-dimensional superlattice structures.