15:45 〜 16:00
[23p-B203-9] Energetics and electronic properties of bilayer Janus WSSe
キーワード：Janus WSSe
Transition metal dichalcogenides (TMDC) have ability to form Janus structures in terms of chalcogen species, because they have atomic layered structures where the transition metal layer is sandwiched by two chalcogen layers. A dipole moment normal to the layer causes unique phenomena, such as Rashba spin splitting, piezoelectric polarization, and second-harmonic generation. Therefore, Janus TMDCs have been attracting much attention in the fields of pure and applied physics. As is the case of the conventional TMDCs, the Janus TMDCs can also form mutilayered structures, where the mutual orientation of dipole in each layer plays crucial role in determining their geometric and electronic structures. Although the electronic structures of monolayer and multilayer Janus TMDC have been reported, little is known for their fundamental properties with respect to their stacking arrangements. Therefore, in this work, we investigated the energetics and electronic properties of bilayer Janus WSSe in terms of their interlayer atomic arrangements, using the density functional theory combined with the effective screening medium method.
Our calculations showed that the interlayer spacing and binding energy of bilayer Janus WSSe depend on the stacking configurations and interlayer atomic arrangement. Bilayer Janus WSSe with AB stacking arrangement are more stable than those with twist stacking arrangement. The Se-Se interface is energetically favorable, while the S-S interface is the least stable for both AB and twisted stacking configurations. Electronic structures of bilayer Janus WSSe are also sensitive to the stacking configuration and interlayer atomic arrangement. These bilayer Janus WSSe are semiconductors with an indirect band gap. Interestingly, the bilayer WSSe with Se-S interfaces possesses type II band edge alignment where the valence band edge and the conduction band edges are located in upper and lower layers, respectively.
Our calculations showed that the interlayer spacing and binding energy of bilayer Janus WSSe depend on the stacking configurations and interlayer atomic arrangement. Bilayer Janus WSSe with AB stacking arrangement are more stable than those with twist stacking arrangement. The Se-Se interface is energetically favorable, while the S-S interface is the least stable for both AB and twisted stacking configurations. Electronic structures of bilayer Janus WSSe are also sensitive to the stacking configuration and interlayer atomic arrangement. These bilayer Janus WSSe are semiconductors with an indirect band gap. Interestingly, the bilayer WSSe with Se-S interfaces possesses type II band edge alignment where the valence band edge and the conduction band edges are located in upper and lower layers, respectively.