Stacking effects on the electronic and optical properties of bilayer transition metal dichalcogenidesMoS2,MoSe2,WS2, and<

Spectroscopic Signatures of AA′ and AB Stacking of Chemical Vapor Deposited Bilayer MoS2

“…A noticeable blue shift of the I peak of AA 0 stacked bilayer by 0.056 ( 0.017 eV over that of the AB stacked bilayer was observed. This observation agrees with the density functional theory (DFT) calculation findings of He et al 9 in terms of the general trend but being different in value (0.06 eV from our PL study versus 0.14 eV from DFT calculations). Previous experimental results 19,21 did not address the difference between the I peak positions of AA 0 and AB stacked bilayer MoS 2 .…”

“…The difference between indirect gap energy in the two MoS 2 phases can also be understood from the perspective of electronic band splitting. DFT simulation results 9 show that AB stacked bilayer MoS 2 has an additional band splitting over that of the AA 0 stacked bilayer. Because of the lack of centro-symmetry in AB stacking, four bands are formed (instead of two in AA 0 stacking) along the MÀKÀΓ direction in the AB stacked bilayer Brillouin zone.…”

“…21 It is mainly defined by the orbital overlap of the inner sulfur atoms from the adjacent MoS 2 layers, 19 with a smaller interlayer distance leading to stronger electronic coupling. 19,21 Both DFT calculation 9,19 and experimental data 36 show that AB stacked bilayer MoS 2 has an interlayer distance smaller than that in the AA 0 stacked bilayer. These findings support our finding.…”

“…6À8 Compared to the more studied monolayer TMDs, bilayer structures offer an added layer degree of freedom. Interactions between MoS 2 layers as well as the specific stacking order can significantly modify their electrical, 9 optical, 3 and vibrational properties. 10 The specific spinÀorbit-based behavior depends sensitively on crystal symmetry, as elucidated by many theoretical studies.…”

Inversion Domain Boundary Induced Stacking and Bandstructure Diversity in Bilayer MoSe2

“…electronic bandgap, in black phosphorus 6,18,19 and PtX2 (X=S or Se) [20][21][22] . Interlayer stacking order was predicted another degree of freedom to modify electronic structures of layered materials and recently demonstrated in twisted homo- 18,[23][24][25] and vdW hetero-bilayers [26][27][28] . Twisted homo-bilayers aside, hetero-bilayers involve electronic states from both different layers with a collective feature from diverse and continuously varied Moiré stacking orders, as a result of non-negligible lattice mismatch.…”