By placing a thin Si layer (less than $100\mathrm{nm}$) on top of a dielectric layer over bulk Si, the optical field at a graphene/silicon Schottky junction can be enhanced by a factor of 8.4 at the wavelength of $700\mathrm{nm}$. The large field enhancement originates from the subnanometer thickness of graphene. The open-cavity structure can be tuned to enhance absorption in the near-infrared region which increases the photocurrent. Model calculations show that although the presence of a thin Si layer reduces the overall photocurrent output, the amount of silicon required to generate a given photocurrent is significantly lower than in conventional silicon solar cells. First experimental devices using graphene on silicon-on-insulator substrates have shown promising initial results.

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• Electrical conductivity
• Graphene
• Interfaces
• Two-dimensional electron system
• Electromagnetic wave theory
• Transfer matrix method