Simple approach for high-contrast optical imaging and characterization of graphene-based sheets

TL;DR

This paper introduces a straightforward optical technique to identify and measure the optical properties of graphene-based materials using substrate contrast, enabling effective characterization of nanometer-thick sheets.

Contribution

It presents a simple, substrate-based optical method for high-contrast imaging and characterization of graphene and related materials, improving measurement accuracy.

Findings

Effective contrast achieved with optimized dielectric layer

Refractive index and absorption coefficients determined for various graphene materials

Method enables rapid, non-destructive characterization

Abstract

A simple optical method is presented for identifying and measuring the effective optical properties of nanometer-thick, graphene-based materials, based on the use of substrates consisting of a thin dielectric layer on silicon. High contrast between the graphene-based materials and the substrate is obtained by choosing appropriate optical properties and thickness of the dielectric layer. The effective refractive index and optical absorption coefficient of graphene oxide, thermally reduced graphene oxide, and graphene are obtained by comparing the predicted and measured contrasts.