1 research outputs found
Direct Measurement of the Tunable Electronic Structure of Bilayer MoS<sub>2</sub> by Interlayer Twist
Using
angle-resolved photoemission on micrometer-scale sample areas, we
directly measure the interlayer twist angle-dependent electronic band
structure of bilayer molybdenum-disulfide (MoS<sub>2</sub>). Our measurements,
performed on arbitrarily stacked bilayer MoS<sub>2</sub> flakes prepared
by chemical vapor deposition, provide direct evidence for a downshift
of the quasiparticle energy of the valence band at the Brillouin zone
center (Γ̅ point) with the interlayer twist angle, up
to a maximum of 120 meV at a twist angle of ∼40°. Our
direct measurements of the valence band structure enable the extraction
of the hole effective mass as a function of the interlayer twist angle.
While our results at Γ̅ agree with recently published
photoluminescence data, our measurements of the quasiparticle spectrum
over the full 2D Brillouin zone reveal a richer and more complicated
change in the electronic structure than previously theoretically predicted.
The electronic structure measurements reported here, including the
evolution of the effective mass with twist-angle, provide new insight
into the physics of twisted transition-metal dichalcogenide bilayers
and serve as a guide for the practical design of MoS<sub>2</sub> optoelectronic
and spin-/valley-tronic devices