Strong dependence of photocurrent on illumination-light colors for ZnO/graphene Schottky diode

The ZnO/graphene Schottky diode reveals a strong dependence of its photocurrent on the color of the illuminating lights (i.e., a dependence of photocurrent on the photon energy). As the photon energy increases, the magnitude of photocurrent is exponentially increased. Particularly, in comparison with the red-light illumination, the device clearly exhibits approximately 100-times-increased photocurrent when illuminating the ultra-violet light. We attribute this feature to the increase in photo-excited carriers at the depletion region in ZnO. The results suggest that the ZnO/graphene Schottky diode holds promise for the application in high-performance color-selectable photodetectors.