Wavelength-selective silicon near infrared photodetector using surface plasmon resonance enhancement

We proposed a wavelength-selective silicon near infrared (NIR) photodetector using the internal photoemission effect enhanced by surface plasmon resonance (SPR). The photodetector employed an Au grating to couple the transverse magnetic (TM) NIR light to surface plasmon to improve the quantum efficiency. The grating coupling also enabled the photodetector to perform wavelength-selective detection. The obtained short circuit current curve indicated that the TM light is coupled to surface plasmon with a resolution of 19nm in the wavelength selectivity. If the wavelength of the incident light is the same, the quantum efficiency (incident photons to current conversion efficiency) of a photodetector is directly proportional to the responsivity. Therefore, to confirm the enhancement of the quantum efficiency by SPR, we measured the responsivity of the proposed photodetector and compared the quantum efficiency of the photodetector with that of a Schottky photodetector (a flat Au film on n type silicon). The responsivity of the proposed photodetector in 1500nm is 0.036mA/W in room temperature. The quantum efficiency was enhanced on the order of 10⁴ times in 1500nm.