Broadband optical properties of monolayer and bulk MoS2

Georgy A Ermolaev,Alexey Y Nikitin,Dmitry E Tatarkin,Aleksey V Arsenin,Andrey A Vyshnevyy,Sergey M Novikov,Yury V Stebunov,Denis G Baranov,Timur Shegai,Valentyn S Volkov,Dmitry I Yakubovsky

doi:10.1038/s41699-020-0155-x

Abstract

Layered semiconductors such as transition metal dichalcogenides (TMDs) offer endless possibilities for designing modern photonic and optoelectronic components. However, their optical engineering is still a challenging task owing to multiple obstacles, including the absence of a rapid, contactless, and the reliable method to obtain their dielectric function as well as to evaluate in situ the changes in optical constants and exciton binding energies. Here, we present an advanced approach based on ellipsometry measurements for retrieval of dielectric functions and the excitonic properties of both monolayer and bulk TMDs. Using this method, we conduct a detailed study of monolayer MoS2 and its bulk crystal in the broad spectral range (290–3300 nm). In the near- and mid-infrared ranges, both configurations appear to have no optical absorption and possess an extremely high dielectric permittivity making them favorable for lossless subwavelength photonics. In addition, the proposed approach opens a possibility to observe a previously unreported peak in the dielectric function of monolayer MoS2 induced by the use of perylene-3,4,9,10-tetracarboxylic acid tetrapotassium salt (PTAS) seeding promoters for MoS2 synthesis and thus enables its applications in chemical and biological sensing. Therefore, this technique as a whole offers a state-of-the-art metrological tool for next-generation TMD-based devices.

Highlights

Two-dimensional (2D) materials possess unique electrical and optical properties[1,2], which make them suitable for a variety of practical applications in photonics and optoelectronics[1]
We validated that synthesized MoS2 is atomically thin using atomic force microscopy (AFM) and resonant function, we can analyze the peaks presented in the optical constants because our approach relies on the physical origin of the transition metal dichalcogenides (TMDs) absorption, to be exact, on the material’s exciton resonances
We have presented a broadband (290–3300 nm) spectroscopic ellipsometry (SE) of monolayer MoS2 grown on SiO2 by atmospheric pressure chemical vapor deposition and bulk MoS2

Summary

Introduction

Two-dimensional (2D) materials possess unique electrical and optical properties[1,2], which make them suitable for a variety of practical applications in photonics and optoelectronics[1] In this regard, one of the most promising is a family of transition metal dichalcogenides (TMDs)[3]. One of the most promising is a family of transition metal dichalcogenides (TMDs)[3] These materials have already been successfully implemented in solar cells[4,5], ultrasensitive photodetectors[6,7], sensors[8,9], optical modulators[10,11], light emitters[12,13], and lasers[14,15], demonstrating even better performance than that of the devices based on graphene[16]. The accurate determination of the optical constants of these materials is nontrivial owing to their complicated excitonic structure

Methods

Results

Conclusion