Probing the Spin-Polarized Electronic Band Structure in Monolayer Transition Metal Dichalcogenides by Optical Spectroscopy

Abstract

We study the electronic band structure in the K/K' valleys of the Brillouin zone of monolayer WSe 2 and MoSe 2 by optical reflection and photoluminescence spectroscopy on dual-gated field-effect devices. Our experiment reveals the distinct spin polarization in the conduction bands of these compounds by a systematic study of the doping dependence of the A and B excitonic resonances. Electrons in the highest-energy valence band and the lowest-energy conduction band have antiparallel spins in monolayer WSe 2 , and parallel spins in monolayer MoSe 2 . The spin splitting is determined to be hundreds of meV for the valence bands and tens of meV for the conduction bands, which are in good agreement with first principles calculations. These values also suggest that both n-and ptype WSe 2 and MoSe 2 can be relevant for spin-and valley-based applications.

Excitonic effects in the optical properties of 2D materials:an equation of motion approach

“…This result makes sense, but when we increase the temperature we never obtain values as small as those reported in the experiments for MoS 2 . It is now known [55] that excitonic spectrum of TDMC's samples in SiO 2 are strongly influence by the disorder of the substrate. In this reference it is shown that encapsulated samples in h-BN have much narrower excitonic peaks.…”

Excitonic Linewidth Approaching the Homogeneous Limit in MoS2 -Based van der Waals Heterostructures

“…Here, charge tunable samples [66] or experiments in transverse magnetic fields [67,68] are expected to give a better indication on the dark-bright order in future experiments on these narrow linewidth samples. The temperature dependence of the PL peak position follows a standard hyperbolic cotangent relation [69]:…”

Photoluminescence Study of B‐Trions in MoS2 Monolayers with High Density of Defects

“…Theoretical calculations show that the same double peak structure is expected also for the B band. [28][29][30] Experimentally the B À trion has been recently observed by reflectance contrast measurements in WSe 2 and MoSe 2 , [31] but attempts to detect the existence of B À (or B þ ) trion by PL have not been successful.…”