Metal–semiconductor–metal ultraviolet photodiodes based on reduced graphene oxide/GaN Schottky contacts

We report on the characteristics of reduced graphene oxide (rGO)/GaN Schottky diodes in which the reduction process is performed at various temperatures. The Schottky barrier height of the rGO/GaN Schottky diode peaks at 1.07 eV with the reduction temperature of 650 °C, caused by changes in the O-containing functional groups and surface Fermi-level pinning during thermal reduction. The interdigitated rGO/GaN metal–semiconductor–metal photodiode using GO reduced at 650 °C exhibits a responsivity of 0.128 A/W under 365-nm illumination, with a sharp cutoff near the GaN energy bandgap.