| Summary: | Thermal annealing in the range of 100–700 °C is applied to reduce the graphene oxide (GO) film into reduced-GO (rGO). Raman spectrum analysis and film conductivity analysis via Hall measurement confirms the advancement of reduction degree at higher annealing temperature (AT). The film conductivity is 19.7 S cm−1 after annealing at 700 °C. Hall measurement also reveals the sudden appearance of electron conduction around 300 °C. The type of attached oxygen functional groups determines the type of majority carrier in the film and modulate the work function of conductive crystalline sp2 carbon. Then, the effect of AT to the current-voltage characteristics of n-type silicon/GO junction are discussed. The fabricated junction is analyzed based on Schottky junction operation using Rhoderick and Cheung methods. The higher reduction degree leads to lower series resistance. Schottky barrier height is found to increase to 0.92 eV for AT around 300 °C, before it decreases at higher AT. Correlation between the barrier height and the hole concentration from Hall measurement can be noticed. Schottky junction with AT of 400 °C gives the highest rectification ratio of 149, owing to moderate value of series resistance as well as high barrier height.
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