Transport properties of n-type ultrananocrystalline diamond films

TL;DR

This study explores how nitrogen doping affects the electrical transport mechanisms in ultrananocrystalline diamond films across various temperatures, revealing a transition from hopping conduction to delocalized electron transport.

Contribution

It demonstrates the impact of nitrogen concentration on the transition from insulating to metallic behavior in ultrananocrystalline diamond films, providing insights into their transport mechanisms.

Findings

Low nitrogen concentration leads to variable range hopping conduction.

High nitrogen concentration results in delocalized electron states.

Critical carrier concentration triggers metal-insulator transition.

Abstract

We investigate transport properties of ultrananocrystalline diamond films for a broad range of temperatures. Addition of nitrogen during plasma-assisted growth increases the conductivity of ultrananocrystalline diamond films by several orders of magnitude. We show that films produced at low concentration of nitrogen in the plasma are very resistive and electron transport occurs via a variable range hopping mechanism while in films produced at high nitrogen concentration the electron states become delocalized and the transport properties of ultrananocrystalline diamond films can be described using the Boltzmann formalism. We discuss the critical concentration of carriers at which the metal to insulator transition in ultrananocrystalline diamond films occurs and compare our results with available experimental data.