S/N Improvement of Au/Si Nano-Antenna Photodetector Using Small Device Area and Converging Lens

This paper reports on Signal Noise ratio (S/N) improvement of an Au/Si nano-antenna photodetector by converging light onto a small device area. The infrared light energy was efficiently absorbed by Au nano-antenna, and was transduced to photocurrent by the Schottky barrier formed on Cr/n-Si interface. When the device area was reduced to 1/25, the amount of dark current noise decreased by about 95%. By converging the incident laser diameter to 1/10 of the initial spot size, S/N improved about 5 times at 1500 nm. Because this method is S/N improvement by a small device area and converging light, it will serve as a fundamental way to efficient infrared measurement with a Schottky photodetector.