Determination of Carrier Type Doped from Metal Contacts to Graphene by Channel-Length-Dependent Shift of Charge Neutrality Points

TL;DR

This paper presents a method to identify whether electrons or holes are transferred from metal contacts to graphene by analyzing how the charge neutrality point shifts with channel length, revealing doping characteristics.

Contribution

It introduces a channel-length-dependent shift technique to determine carrier type doping from metal contacts to graphene, linking shifts to metal work function modifications.

Findings

Dirac point shifts with channel length indicate carrier type.

Shorter channels cause more negative or positive Dirac point shifts.

Metal work functions influence doping behavior in graphene.

Abstract

A method for determining the type of charge carrier, electron or hole, which is transferred from metal contacts to graphene, is described. The Dirac point is found to shift toward more negative (positive) gate voltages for electron (hole) doping by shortening of the interelectrode spacing. The shift of the Dirac point is accompanied by an enhancement of the electron-hole conductivity asymmetry. Experimentally determined carrier types may be explained in terms of the metal work functions modified by interactions with graphene.