Near-Infrared Si Based Photodetector Using Au/Si Nano-Antenna Structures

Abstract

We developed a near-infrared photodetector using nano-pillars formed on an n-typed Si wafer. Au nano-pillars performed as optical antennas, which absorb the infrared light effectively. Each nano-pillar had several hundreds nm of diameter, 1.0-µm-height, and was arrayed with 2-µm-pitch over 100 µm ×100 µm area, fabricated using a MEMS 8-inch line. The absorbed photo energy was transduced to photocurrent by a Schottky barrier formed at the interface between the Au/Cr and n-typed Si. The photocurrent sensitivity (responsivity) of the nano-pillar photodetector exhibited around 10-times increase in average, and 23-times in the maximum, compared with a control Schottky typed photodetector with a flat Au surface. The detectable wavelength limit was extended to 1.8 µm. Because this method was clarified to be compatible with a standard Si fabrication process, it will serve as a fundamental way to construct a photodetector for multi-wavelength photodetection.