Electronic properties of rhombohedrally stacked bilayer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi mathvariant="normal">W</mml:mi><mml:msub><mml:mi>Se</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> obtained by chemical vapor deposition
Aymen Mahmoudi, Meryem Bouaziz, Anis Chiout, Gaia Di Berardino, Nathan Ullberg, Geoffroy Kremer, Pavel Dudin, J. Ávila, Mathieu G. Silly, Vincent Derycke, Davide Romanin, Marco Pala, Iann C. Gerber, Julien Chaste, Fabrice Oehler, Abdelkarim Ouerghi
Abstract
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., ${0}^{\ensuremath{\circ}}$ 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 $\mathrm{W}{\mathrm{Se}}_{2}$ homobilayers obtained in stable $3R$ configuration by chemical vapor synthesis. We investigate the electronic and structural properties of these $3R\phantom{\rule{4pt}{0ex}}\mathrm{W}{\mathrm{Se}}_{2}$ bilayers with $3R$ stacking using micro-Raman spectroscopy, angle-resolved photoemission nanospectroscopy measurements, and density functional theory calculations. Our results demonstrate that $\mathrm{W}{\mathrm{Se}}_{2}$ bilayers with $3R$ crystal phase (AB stacking) show a significant valence-band splitting at the $K$ point estimated at $550\ifmmode\pm\else\textpm\fi{}20$ meV. We derived experimentally effective hole masses of $0.48{m}_{e}$ and $0.73{m}_{e}$ 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.