Optimal design of photodetector with multi-slit grating

We propose an optimal structure for an Au/Si Schottky-type photodetector with a multi-slit grating that excites surface plasmon polaritons (SPPs). The intensity of the SPPs excited by the grating is simulated using the finite-difference time-domain method. The calculation results show that the optimum Au film thickness and slit pitch were determined by the resonance effects of SPPs inside the slit and the in-phase interference of the SPPs generated by each slit, respectively. Using these results, we fabricate and evaluate an optimal photodetector with the grating. We also confirm the operation of metal-oxide-semiconductor field-effect transistors by the SPP-enhanced photocurrent.