Encapsulation narrows excitonic homogeneous linewidth of exfoliated MoSe2 monolayer

W Martin Eric,Hui Deng,Jason Horng,Michael-Henr Wentzel,G Ruth Hanna,Eunice Paik,T Cundiff Steven,G Cerullo,J Ogilvie,R Li,F Kärtner,M Khalil

doi:10.1051/epjconf/201920506021

Abstract

We use collinear multidimensional coherent spectroscopy to measure van der Waals structures with a nearly diffraction-limited spot size. Encapsulation by boron nitride narrows the homogeneous and inhomogeneous linewidths of excitonic resonances in MoSe2.

Highlights

transition metal dichalcogenides (TMDCs) are known to have widely varying excitonic linewidths that depend on the local environment, excitation source, and sample history
Many of these inconsistencies have been remedied by encapsulation of the monolayer in hexagonal boron nitride, which both controls the dielectric environment and protects the TMDC
We report some negative attributes of the non-encapsulated samples that the protective hexagonal boron nitride (hBN) encapsulation prevents: we measure lasting broadening of the homogenenous linewidth of nonencapsulated samples by relatively weak

Summary

Introduction

TMDCs are known to have widely varying excitonic linewidths that depend on the local environment, excitation source, and sample history (i.e. temperature cycles and exposure to laser radiation). Encapsulation has led to photoluminescence linewidths that approach previous homogeneous linewidth measurements of nonencapsulated samples [2]. We use multidimensional coherent spectroscopy (MDCS) to compare the neutral exciton lineshapes of fully hBN-encapsulated molybdenum diselenide (MoSe2) monolayer samples and non-encapsulated samples.

Results

Conclusion