Synthesis and electronic structure of atomically thin 2H-MoTe2

An in-depth understanding of the electronic structure of 2H-MoTe2 at the atomic layer limit is a crucial step towards its exploitation in nanoscale devices. Here, we show that millimeter-sized monolayer (ML) MoTe2 samples, as well as smaller sized bilayer (BL) samples, can be obtained using the mechanical exfoliation technique. The electronic structure of these materials is investigated by angle-resolved photoemission spectroscopy (ARPES) for the first time and by density functional theory (DFT) calculations. The comparison between experiments and theory allows us to describe ML MoTe2 as a semiconductor with a direct gap at the K point. This scenario is reinforced by the experimental observation of the conduction band minimum at K in Rb-doped ML MoTe2, resulting in a gap of at least 0.924 eV. In the BL MoTe2 system, the maxima of the bands at Γ and K show very similar energies, thus leaving the door open to a direct gap scenario, in analogy to WSe2. The monotonic increase in the separation between spin-split bands at K while moving from ML to BL and bulk-like MoTe2 is attributed to interlayer coupling. Our findings can be considered as a reference to understand quantum anomalous and fractional quantum anomalous Hall effects recently discovered in ML and BL MoTe2 based moiré heterostructures.