On the origin of the electric carrier concentration in graphite

TL;DR

This study shows that the electrical carrier concentration in graphite is primarily influenced by defects and impurities rather than being an intrinsic property, with defect-induced increases in carrier density reducing resistivity.

Contribution

It provides experimental evidence linking defect concentration to carrier density in graphite, clarifying the origin of its electrical properties.

Findings

Resistivity decreases with defect introduction at low fluences.

Carrier density in graphite is significantly affected by defects and impurities.

Resistivity change aligns with theoretical estimates of defect-induced carriers.

Abstract

We investigate the dependence of the electrical resistivity of $\sim 60 $nm thick single crystalline graphite samples on the defect concentration produced by proton irradiation at very low fluences. We show that the resistivity decreases few percent at room temperature after inducing defects at concentrations as low as $\sim 0.1 $ppm due to the increase in the carrier density, in agreement with theoretical estimates. The overall results indicate that the carrier densities measured in graphite are not intrinsic but related to defects and impurities.