Figure 1: Scheme and energy band diagram of the graphene/TiO2 Schottky nanodiode.
From: Hot carrier multiplication on graphene/TiO2 Schottky nanodiodes

(a) Scheme and (b) cross–sectional view (photograph) of the graphene/TiO2 Schottky nanodiode. Energy band diagrams for hot CM by (c) impact ionization and (d) inverse Auger process from photon absorption on the graphene/TiO2 Schottky nanodiode. Here, the filled (empty) dots indicate electrons (holes).