Enhancement of graphene visibility on transparent substrates by refractive index optimization

TL;DR

This paper introduces a refractive index optimization method in optical reflection microscopy that significantly enhances the visibility of graphene flakes on transparent substrates by using an immersion liquid with a matching refractive index.

Contribution

It presents a novel approach employing refractive index matching with immersion liquids to improve graphene imaging contrast in optical reflection microscopy.

Findings

Contrast of graphene flakes increased by a factor of 4

Enhanced resolution and contrast in graphene imaging

Method applicable to various transparent substrates

Abstract

Optical reflection microscopy is one of the main imaging tools to visualize graphene microstructures. Here is reported a novel method that employs refractive index optimization in an optical reflection microscope, which greatly improves the visibility of graphene flakes. To this end, an immersion liquid with a refractive index that is close to that of the glass support is used in-between the microscope lens and the support improving the contrast and resolution of the sample image. Results show that the contrast of single and few layer graphene crystals and structures can be enhanced by a factor of 4 compared to values commonly achieved with transparent substrates using optical reflection microscopy lacking refractive index optimization.