Abstract
We report on the effects of surface passivation with a polymethylmethacrylate (PMMA) layer and annealing of a graphene sheet on the electrical characteristics of Au/graphene/n-Si Schottky junction diodes. For this study, single-layer graphene sheets were grown by chemical vapor deposition. The Schottky diodes were fabricated by transferring the graphene sheets directly onto n-type Si substrates. The electrical properties, including the Schottky barrier heights and ideality factors of the Au/Gr/n-Si Schottky diodes, were evaluated using current-voltage and capacitance voltage measurements. With both annealing of the graphene layer at 400 degrees C and surface passivation of the PMMA layer, we found that the graphene/n-Si Schottky diodes showed significantly reduced electrical degradation by preventing H2O and/or O-2 molecules from forming at the interface between the Gr layer and the n-Si substrate.