Demonstration of distinct semiconducting transport characteristics of monolayer graphene functionalized via plasma activation of substrate surfaces

TL;DR

This study demonstrates that plasma activation of substrate surfaces induces semiconducting behavior in monolayer graphene, characterized by a transport gap, high on/off ratio, and defect-related transport mechanisms, opening new avenues for graphene-based electronics.

Contribution

The paper introduces a novel substrate surface-activation method that functionalizes graphene to exhibit semiconducting properties, unlike pristine graphene.

Findings

Graphene on activated substrates shows a transport gap and nonlinear transfer characteristics.

A high on/off ratio of 600 at cryogenic temperatures is achieved.

Weak localization and hopping transport indicate defect-induced carrier localization.

Abstract

We report semiconducting behavior of monolayer graphene enabled through plasma activation of substrate surfaces. The graphene devices are fabricated by mechanical exfoliation onto pre-processed SiO2/Si substrates. Contrary to pristine graphene, these graphene samples exhibit a transport gap as well as nonlinear transfer characteristics, a large on/off ratio of 600 at cryogenic temperatures, and an insulating-like temperature dependence. Raman spectroscopic characterization shows evidence of sp3 hybridization of C atoms in the samples of graphene on activated SiO2/Si substrates. We analyze the hopping transport at low temperatures, and weak localization observed from magnetotransport measurements, suggesting a correlation between carrier localization and the sp3-type defects in the functionalized graphene. The present study demonstrates the functionalization of graphene using a novel substrate surface-activation method for future graphene-based applications.