Phonons in WSe2/MoSe2 van der Waals Heterobilayers

• Published in: physica status solidi (b) Vol. 259; no. 1
• Main Authors: Mahrouche, Fayssal, Rezouali, Karim, Mahtout, Sofiane, Zaabar, Foudil, Molina-Sánchez, Alejandro
• Format: Journal Article
• Language: English
• Published: 01.01.2022
• Subjects: 2D materials; density functional perturbation theory; DFT; first-principles calculations; interlayer phonons; transition metal dichalcogenides; van der Waals heterostructures
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.202100321

The first‐principles calculations of the structural and vibrational properties of the synthesized 2D van der Waals (vdW) heterobilayers (HBLs) formed by single‐layer dichalcogenides MoSe2 and WSe2 are reported. When combining these systems in periodic 2D heterostructures, the intrinsic phonon characteristics of the free‐standing constituents are to a large extent preserved but, furthermore, exhibit shear and breathing phonon modes that are not present in the individual building blocks. These unusual modes, which are extremely sensitive to weak vdW forces, could be a useful tool for the characterization of the optical properties of vdW heterostructures. In addition to these features, the departure of flexural modes of the HBL from the ones of its monolayer parents is also found. Structural and vibrational properties of van der Waals heterobilayers (HBLs) WSe2/MoSe2 are studied using density‐functional theory. The first‐principles results reveal the existence of interlayer rigid‐layer shear and breathing phonon modes in the HBLs. These special low‐frequency optical modes exist only in bilayers and are paramount to understanding the different scattering mechanisms in layered 2D materials.