Micro-reflectance and transmittance spectroscopy: a versatile and powerful tool to characterize 2D materials

TL;DR

This paper presents a versatile optical microscope setup for differential reflectance and transmittance spectroscopy of 2D materials, enabling detailed characterization of their optical properties and layer number with high spatial resolution.

Contribution

It provides a detailed description of an experimental setup for optical spectroscopy of 2D materials, filling a gap in the literature.

Findings

Effective determination of layer number in 2D materials

Characterization of excitonic resonances in transition metal dichalcogenides

High spatial resolution (~1 micron) in optical measurements

Abstract

Optical spectroscopy techniques such as differential reflectance and transmittance have proven to be very powerful techniques to study 2D materials. However, a thorough description of the experimental setups needed to carry out these measurements is lacking in the literature. We describe a versatile optical microscope setup to carry out differential reflectance and transmittance spectroscopy in 2D materials with a lateral resolution of ~1 micron in the visible and near-infrared part of the spectrum. We demonstrate the potential of the presented setup to determine the number of layers of 2D materials and to characterize their fundamental optical properties such as excitonic resonances. We illustrate its performance by studying mechanically exfoliated and chemical vapor-deposited transition metal dichalcogenide samples.