Silicon Photo-Diode Using Surface-Plasmon Resonance

Abstract

The concept of nano-photodiode, employing surface-plasmon antenna to create sub-wavelength size nearfield, is described in relation to silicon photonics. Response time of the prototype silicon nano-photodiode was much shorter (-20 ps) than that of conventional silicon photodiodes (>1 ns). There are two reasons for the high-speed response: short distance between electrodes (-100 nm) and small electrode area (< 1 μm2). The former is realized by lapping near-field region over depletion region (Schottky barrier) in silicon thereby eliminating time-consuming carrier diffusion process. The latter results in small electrode capacitance and thus reducing response time of the photodiode circuit. This nano-photodiode technology can be applied to other semiconductor materials such as germanium and ternary compound semiconductors.