Electronic Structure of Twisted Bilayers of Graphene/MoS₂ and MoS₂/MoS₂

Abstract

Vertically stacked two dimensional multilayer structures have become a promising prototype for functionalized nano devices due to their wide range of tunable properties. In this paper we performed first-principles calculations to study the electronic structure of non-twisted and twisted bilayers of hybrid graphene/MoS 2 (Gr/MoS 2 ) and MoS 2 /MoS 2 . Both twisted bilayers of Gr/MoS 2 and MoS 2 /MoS 2 show significant differences in band structures from the non-twisted ones with the appearance of the crossover between direct and indirect band gap and gap variation. More interestingly, the band structures of twisted Gr/MoS 2 with different rotation angles are very different from each other while those of MoS 2 /MoS 2 are very similar. The variation of band structure with rotation angle in Gr/MoS 2 is, indeed, originated from the misorientation-induced lattice strain and the sensitive band-strain dependence of MoS 2 .

Bandgap inhomogeneity of MoS2 monolayer on epitaxial graphene bilayer in van der Waals p-n junction

“…5, the position of the maximum of the valence band of MoS 2 can be tuned effectively by uniform tensile biaxial strain variation. Similar theoretical observations [46] were also reported about tuning the properties of MoS 2 , subjected to various levels of misorientation-induced lattice strain, through varying the angle between graphene and MoS 2 . This suggests that tuning the interlayer orientation could induce a strain change in MoS 2 which may cause variations of MoS 2 bandstructure [32,47].…”

Tuning the electronic structure of monolayer graphene/MoS2van der Waals heterostructures via interlayer twist

“…3a-3d, the measured graphene-derived bands agree well with the NNTB bands of intrinsic graphene. Note that for all measured twist angles, there is no indication of band hybridization for Gr in the range of binding energies measured in this study, which is in good agreement with theoretical predictions [22]. In the corresponding momentum distribution curve (MDC) plot and second derivative plot, we can confirm the absence of hybridization (Supplementary Figure S7).…”

“…Quantitatively, the charge transfer amount in Ref. [22] is ~10 -4 electron per carbon (e/C). The position of the Fermi level of Gr can be estimated using | | [36], where is the Fermi velocity, and is the carrier concentration in Gr.…”

Moiré-related in-gap states in a twisted MoS2/graphite heterojunction

“…This is not as expected according to first-principles calculations, which predict that the band structure varies with the rotational angle of the twisted bilayer. 29,30 We suggest that typical STM set-point parameters as used by Huang et al, such as a current feedback set-point on the order of tens of pico-Amperes and a bias setpoint far into the conduction band, chosen to reduce the influence of the tip's electric field, 23, 31 may actually render the measurement insufficiently sensitive to potential moiré related interfacial phenomena. For a further discussion of the effects of different tip-sample distance, we present a series of tunneling spectra by using different set-points in the Supplementary Information.…”

“…(5,4) in the hexagonal basis sets of the MoS 2 and graphite lattices. 29,32 Note that the actual supercell period is not necessarily equal to the apparent moiré pattern's period. Generally, adjacent apparent moiré peaks are seen to have a small difference upon close inspection, and a larger periodicity is necessary for finding another point of exactly commensurate stacking.…”