Conductivity crossover in nano-crystalline diamond films: Realization of a disordered superlattice-like structure

TL;DR

This study investigates how nitrogen doping influences electrical conduction in nano-crystalline diamond films, revealing a transition from localized hopping to metallic conduction and potential for high-speed device applications.

Contribution

It introduces a disordered quasi-superlattice model to explain conduction mechanisms in nitrogen-doped diamond films, demonstrating controllable disorder and a conductivity crossover.

Findings

Transition from localized to metallic conduction with increased nitrogen

Observation of a crossover from hopping to weak localization

Potential for high-speed diamond-based electronic devices

Abstract

We present the electrical transport characteristics of a batch of nano-crystalline diamond films of varying nitrogen concentrations and explain the conduction mechanism by the disordered quasi-superlattice model applied to semiconductor heterostructures. Synthesized by the hot filament chemical vapour deposition technique, the degree of structural disorder in the films, confirmed from Raman spectroscopy, is found to be controllable, resulting in the transition of conduction mechanism from localized and activated to the metallic conduction regime. Hence through high field magneto-resistance measurements at low temperatures we firmly establish a conductivity crossover from hopping to 3D weak localization. The long electronic dephasing time and its weak temperature dependence suggest the possibility for diamond-based high-speed device applications.