Transport in chemically doped graphene in the presence of adsorbed molecules

TL;DR

This study investigates how adsorbed molecules affect charge transport in chemically doped graphene, revealing increased mobility and electron-hole asymmetry, with results aligning well with experimental data.

Contribution

It demonstrates that adsorbed molecules can enhance graphene mobility by neutralizing charged impurities, a novel insight for sensor applications.

Findings

Adsorbed molecules increase graphene mobility.

Field-effect measurements show electron-hole asymmetry.

Calculated magnetoresistance matches experimental data.

Abstract

Motivated by a recent experiment reporting on the possible application of graphene as sensors, we calculate transport properties of 2D graphene monolayers in the presence of adsorbed molecules. We find that the adsorbed molecules, acting as compensators that partially neutralize the random charged impurity centers in the substrate, enhance the graphene mobility without much change in the carrier density. We predict that subsequent field-effect measurements should preserve this higher mobility for both electrons and holes, but with a voltage induced electron-hole asymmetry that depends on whether the adsorbed molecule was an electron or hole donor in the compensation process. We also calculate the low density magnetoresistance and find good quantitative agreement with experimental results.