Fig. 5
Interpretation of band alignments and luminescence features. a Typical band diagram for a 3D Schottky contact between a metal and an n-type semiconductor. The double-headed arrows illustrate the alignments of work function W, Schottky barrier height ϕB and electron affinity χ. b, c 2D Schottky alignment diagrams for b a SLG/WS2 contact and c a BLG/WS2 contact in UHV. The trend of the band alignments has been derived from the EDCs in Fig. 4. d Sketch of optically induced trion (electron–electron–hole (eeh) type) and exciton processes in SL WS2 under a different bias Δϕ caused by the varying Schottky barrier heights. Full (hollow) spheres correspond to electrons (holes), the red arrow corresponds to an optical pulse and the blue arrow signifies an electron–hole pair excitation
