Interlayer Phonon Modes of MoSe₂ and WSe₂ Observed by THz Emission Spectroscopy

Abstract

Terahertz (THz) time domain emission spectroscopy was performed on bulk single crystal MoSe 2 and WSe 2 . Results show THz emission signals which comprise of a single cycle transient current-driven signal and damped oscillatory signals arising from coherent phonon modes. The damped oscillations have frequencies below 1 THz and are attributed to interlayer shear and breathing modes.