English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Micro-Raman spectroscopy has become an important tool in probingthermophysical behavior in emerging functional materials such astwo-dimensional (2D) layered structures. Localized heating by the focused Ramanexcitation laser beam is expected to produce both stress and nonequilibriumtemperature distributions in the material. Here we investigate the effects ofhot optical phonons in the Raman spectra of molybdenum disulphide (MoS2) anddistinguish them from those caused by thermally-induced compressive stress,which causes a Raman frequency blue shift in the focused Raman laser spot. Withthe stress effect accounted for in micro-Raman measurements, the degree ofnonequilibrium between the hot optical phonons and the acoustic phonon bath isfound to be much smaller than those observed in prior micro-Raman measurementsof suspended graphene. The observation agrees with a first-principles basedtheoretical prediction of overpopulated zone-center optical phonons compared toother optical phonons in the Brillouin zone and acoustic phonons. The findingsprovide detailed insight into the energy relaxation processes in this emerging2D transition metal dichalcogenide (TMD) electronic and optoelectronic materialand clarify an important question in micro-Raman measurements of thermaltransport in this and other 2D materials.

Effects of hot phonons and thermal stress in micro-Raman spectra of molybdenum disulphide