Multi-angle comparisons of uniformly Au-doped and undoped MoTe₂ FETs. (a) Optical image of the two MoTe₂ FETs. (b) Drain voltage dependent transfer characteristic curves. (c) Raman curves of uniformly doped and undoped MoTe₂. (d) Surface potential image of MoTe₂ on Au and SiO₂ substrates. (e) Potential line profile across the edge of the Au corresponding to the white line in (d). The inset is the optical microscope image of MoTe₂ layer stack on the Au film and the insulating silicon substrate. (f) Band alignment of MoTe₂/MoS₂ heterojunction with the undoped MoTe₂ (left) and the doped MoTe₂ (right). (g) Rectification curves of doped and undoped MoS₂/MoTe₂ pn junction. (h) Band diagrams of the uniformly doped (blue) and undoped (grey) MoS₂ along the channel length.