Fig. 1: Photogenerated charge carrier transport in 2D heterostructures with vertical and lateral transport channels.
a Schematic diagram illustrating the diffusion process of photogenerated charge carriers in both vertical and lateral channel devices, with incident light directed from above onto the overlapped heterojunction region. The red and blue spheres represent holes and electrons, respectively. b Steady-state photogenerated charge carrier distribution as a function of distance from the p-n junction when excess electrons and holes are exclusively generated at the p-n junction region. Ld represents the diffusion length of the charge carriers. n0 refers to the photogenerated carrier concentration at the p-n junction region. c, d Schematic energy band diagram showing the electron-hole pair generation, separation, diffusion, and recombination processes in both vertical (c) and lateral channel devices (d). The red and blue dashed arrows indicate the transport directions of photogenerated holes and electrons, respectively. The blue and orange shaded areas correspond to the depletion and neutral regions, respectively.
