Fig. 1
From: Ultrasensitive all-2D MoS2 phototransistors enabled by an out-of-plane MoS2 PN homojunction
MoS2-based phototransistors with an out-of-plane PN homojunction. a Optical microscopy image of the few layer MoS2-based device with Ti/Au as source and drain electrodes, the scale bar is 20 µm. b Atomic force microscopy image of the device depicting a thickness of 7.2 nm. The scale bar is 10 µm. c Schematic diagram of the device after surface doping under light illumination consisting of P-MoS2 on top surface and N-MoS2 underneath. The photo-excited holes remain trapped in P-MoS2 while the electrons transport and recirculate in N-MoS2 channel. d Transfer characteristics of the pure N-MoS2 detector and surface doped device with an out-of-plane PN junction, showing the V T shift towards positive-gate voltage
