Extended Data Fig. 1: Device images.
a,b, Optical micrographs for device 1 (a) and 2 (b). The top gate (red dashed line), bottom gate (red line), W-layer (green line), Mo-layer (blue line) and the exciton contact hBN layers (yellow lines) are outlined. The red- and pink-shaded areas denote the device channel and exciton contact regions, respectively. The contact electrodes to the Mo- and W-layers are numbered in orange and blue, respectively. c, Schematic cross section of the devices showing the doping profile. Region I, II and III are the channel, the exciton contact and the metal-semiconductor contacts, in increasing order of doping concentration and darkness of the color (orange for electron doping, blue for hole doping). TG, BG, Pt and Bi denote top gate, bottom gate, platinum electrode and bismuth electrode, respectively.
