Electronic properties of rhombohedrally stacked bilayer WSe2 obtained by chemical vapor deposition

Twisted layers of atomically thin two-dimensional materials support a broad range of quantum materials with engineered optical and transport properties. Transition metal dichalcogenides (TMDs) in the rhombohedral (3R, i.e., 0 & DEG; twist) crystal phase have been the focus of significant research interest in optical applications due to their particular broken inversion symmetry. Here, we report experimental and theoretical study of WSe2 homobilayers obtained in stable 3R configuration by chemical vapor synthesis. We investigate the electronic and structural properties of these 3R WSe2 bilayers with 3R stacking using micro-Raman spectroscopy, angleresolved photoemission nanospectroscopy measurements, and density functional theory calculations. Our results demonstrate that WSe2 bilayers with 3R crystal phase (AB stacking) show a significant valence-band splitting at the K point estimated at 550 & PLUSMN; 20 meV. We derived experimentally effective hole masses of 0.48me and 0.73me at the K point for upper and lower bands, respectively. Our work opens up perspectives for the development of optoelectronic and spintronic devices based on 3R TMD homobilayers.