Jong Yun Choi1,2,Hyun Je Cho1,2,Suk-Ho Lee1,2,Geonho Mun1,2,Heon-Su Ahn1,2,Hwang-Jung Chang1,2,Hyunjin Jung2,3,Moon-Ho Jo1,2
Center for Van der Waals Quantum Solids, IBS (Institute of Basic Science)1,Pohang University of Science and Technology2,Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS)3
Jong Yun Choi1,2,Hyun Je Cho1,2,Suk-Ho Lee1,2,Geonho Mun1,2,Heon-Su Ahn1,2,Hwang-Jung Chang1,2,Hyunjin Jung2,3,Moon-Ho Jo1,2
Center for Van der Waals Quantum Solids, IBS (Institute of Basic Science)1,Pohang University of Science and Technology2,Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS)3
We report atomically coherent layer-by-layer epitaxial growth of MoS<sub>2</sub>/WS<sub>2</sub> van der Waals (vdW) heterostructure with metal-organic chemical vapor deposition (MOCVD) which enables vertical stacking of atomically thin semiconductors without interlayer atomic mixing. Engineering the miscut angle of c-plane sapphire substrate, we first achieved the epitaxial growth of single crystalline WS<sub>2</sub> monolayer (ML) template as base layer. Single crystalline texture was confirmed by microscopies and transmission electron microscope (TEM) studies. Moreover, low energy electron diffraction (LEED) measurements at several different points perfectly exhibited 3-fold symmetry without any angle deviation. We also demonstrated coherent ML-by-ML epitaxial growth of MoS<sub>2</sub> on top of single crystalline WS<sub>2</sub> film. VdW epitaxy is kinetically controlled in the near-equilibrium limit, resulting in the tunable two-dimensional (2D) vdW electronic systems. Coherent monolayer stacking was verified by transmission electron microscope studies and optical characterization. Our AA’(2H) and AB(3R) stacked MoS<sub>2</sub>/WS<sub>2</sub> heterostructures showed strong interlayer coupling. Furthermore, electronic and optoelectronic properties of coherent vdW heterostructures were obtained. Our work suggests synthetic material platform of various 2D coherent heterostructures for future application in electronic and photonic nano devices.<br/><br/><b>References</b><br/><i>1. Jin, G., Lee, CS., Okello, O.F.N. et al. Heteroepitaxial van der Waals semiconductor superlattices. Nat. Nanotechnol. <b>16</b>, 1092–1098 (2021).<br/>2. Li, T., Guo, W., Ma, L. et al. Epitaxial growth of wafer-scale molybdenum disulfide semiconductor single crystals on sapphire. Nat. Nanotechnol. <b>16</b>, 1201–1207 (2021).<br/>3. Kim, Y., Cruz, S., Lee, K. et al. Remote epitaxy through graphene enables two-dimensional material-based layer transfer. Nature <b>544</b>, 340–343 (2017).</i>