devices in nano-ARPES

We investigate the effects of electrostatic doping on a 2D topological semimetal, monolayer WTe₂, employing nanometer-resolution angle-resolved photoemission spectroscopy (nano-ARPES). The exfoliated WTe₂ monolayer flake rests on an hBN flake and is capped by a monolayer of hBN to prevent oxidation and allow cleaning. During the photoemission measurements a gate voltage can be applied between a thin graphite electrode beneath the hBN and a graphene contact that overlaps the WTe₂ on top. The gate is observed to shift the Fermi energy by more than 100 meV, from valence to conduction band of monolayer WTe₂. The temperature and doping dependence of the spectrum yield insights into the nature of the bulk conductivity.