Silicon-based plasmonic photodetector in the near-infrared region with a Schottky barrier properly controlled by nanoalloys

Plasmonic Schottky devices have attracted considerable attention for use in practical applications based on photoelectric conversion because they enable to harvest light below the bandgap of semiconductors. In particular, silicon (Si)-based plasmonic Schottky devices have great potential for useful photodetection in the near-infrared region. However, the internal quantum efficiency (IQE) values of previously reported devices have been low because the Schottky barrier is excessively high. Here, we are the first to develop AuAg nanoalloy–n-type Si plasmonic Schottky devices by cathodic arc plasma deposition. These plasmonic nanostructures can be fabricated in only ~1 min. The fabricated AuAg nanoparticles-film structure enables proper control of the Schottky barrier height and increases the area of the Schottky interface for electron transfer. As a result, the considerably enhanced IQE of our device at 1310 nm (1550 nm) is 4.6 (6.5) times higher than those in previous reports, and these responsivities are a record high.