Effect of oxygen plasma etching on graphene studied with Raman spectroscopy and electronic transport

TL;DR

This study investigates how oxygen plasma etching affects graphene's structure and electronic properties using Raman spectroscopy and transport measurements, revealing disorder, doping, and defect-related phenomena.

Contribution

It provides detailed analysis of plasma-induced disorder and doping effects in graphene, with insights into defect evolution and electronic behavior.

Findings

I(D)/I(G) ratio initially increases then decreases with etching pulses

High etching levels nearly suppress the 2D peak while maintaining the D peak

Electronic measurements show hole doping and altered transport properties

Abstract

We report a study of graphene and graphene field effect devices after exposure to a series of short pulses of oxygen plasma. We present data from Raman spectroscopy, back-gated field-effect and magneto-transport measurements. The intensity ratio between Raman "D" and "G" peaks, I(D)/I(G) (commonly used to characterize disorder in graphene) is observed to increase approximately linearly with the number (N(e)) of plasma etching pulses initially, but then decreases at higher Ne. We also discuss implications of our data for extracting graphene crystalline domain sizes from I(D)/I(G). At the highest Ne measured, the "2D" peak is found to be nearly suppressed while the "D" peak is still prominent. Electronic transport measurements in plasma-etched graphene show an up-shifting of the Dirac point, indicating hole doping. We also characterize mobility, quantum Hall states, weak localization and various scattering lengths in a moderately etched sample. Our findings are valuable for understanding the effects of plasma etching on graphene and the physics of disordered graphene through artificially generated defects.