Spatially resolved optical absorption spectroscopy of single- and few-layer MoS2 by hyperspectral imaging

TL;DR

This study develops a hyperspectral imaging technique to spatially resolve the optical absorption properties of single- and few-layer MoS2, revealing insights into its bandgap characteristics with diffraction-limited resolution.

Contribution

The paper introduces a novel hyperspectral imaging method for analyzing the optical absorption of 2D materials at high spatial resolution, applicable to indirect and non-semiconducting systems.

Findings

Hyperspectral imaging effectively probes optical properties of MoS2.

The technique distinguishes between direct and indirect bandgap behaviors.

It enables spatial mapping of optical variations in 2D materials.

Abstract

The possibility of spatially resolving the optical properties of atomically thin materials is especially appealing as they can be modulated at the micro- and nanoscale by reducing their thickness, changing the doping level or applying a mechanical deformation. Therefore, optical spectroscopy techniques with high spatial resolution are necessary to get a deeper insight into the properties of two-dimensional materials. Here we study the optical absorption of single- and few-layer molybdenum disulfide (MoS2) in the spectral range from 1.24 eV to 3.22 eV (385 nm to 1000 nm) by developing a hyperspectral imaging technique that allows one to probe the optical properties with diffraction limited spatial resolution. We find hyperspectral imaging very suited to study indirect bandgap semiconductors, unlike photoluminescence that only provides high luminescence yield for direct gap semiconductors. Moreover, this work opens the door to study the spatial variation of the optical properties of other two-dimensional systems, including non-semiconducting materials where scanning photoluminescence cannot be employed.