micro-ARPES imaging of the conduction band and moiré replicas in 2D semiconductors

We present measurements of the conduction band in WS₂-on-WSe₂ moiré heterobilayers using submicron angle-resolved photoemission spectroscopy The heterobilayers are partially capped by graphene and are electrostatically doped in situ. We find that, at all twist angles, the conduction band edge is the WS₂ K-point valley while the Q-point valley is at slightly higher energy. The measured band gap is 1.58 ± 0.03 eV and in one device we observe the conduction band curvature with an effective mass of 0.15m_e. We also observe replicas of the WS₂ conduction band displaced by reciprocal lattice vectors of the moiré superlattice, whose three-fold intensity pattern can be explained by interference between multiple moiré potential-induced scattering pathways.