A Fast and Sensitive Schottky Photodiode With Surface Plasmon Enhanced Photocurrent and Extremely Low Dark Current for High-Frequency Applications in Near-Infrared

Abstract

High-speed, high-photoresponse, low-dark current photodetectors with monolithic integration compatibility on a single silicon chip have a vital role in fast optical communication. Schottky barrier junctions provide ultrahigh frequency bandwidth, which makes them suitable for a high-speed data rate optical transition system. In this article, we proposed the novel design of a fast silicon Schottky photodiode (SPD) with reduced dark current and enhanced photocurrent to produce an acceptable photo-to-dark current ratio. A differential Schottky diode is used in series with the designed SPD to reduce the final dark current delivered to the next signal conditioner electronics. A periodic plasmonic array is applied on the metallic Schottky contact layer to localize the illuminated light in the depletion region of Schottky contact and increase light absorption, which results in enhanced photocurrent. The simulation of the device shows a photo-to-dark current ratio of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${2.7} \times {10}^{{4}}$ </tex-math></inline-formula> at room temperature and 1-V biasing voltage, which is much greater than the reported data. Moreover, the design results in a complementary metal–oxide–semiconductor (CMOS)-compatible photodiode (PD) with 28-time reduced dark current and 3.3-time photocurrent enhancement with an ultrafast impulse response of 3 ps and a response time of about 18 ps that are attractive for ultra-fast data communication applications in 850-nm region.