45-GHz bandwidth-efficiency resonant-cavity-enhanced ITO-Schottky photodiodes

Abstract—High-speed Schottky photodiodes suffer from low efficiency mainly due to the thin absorption layers and the semitransparent Schottky-contact metals. We have designed, fabricated and characterized high-speed and high-efficiency AlGaAs–GaAs-based Schottky photodiodes using transparent indium–tin–oxide Schottky contact material and resonant cavity enhanced detector structure. The measured devices displayed res-onance peaks around 820 nm with 75 % maximum peak efficiency and an experimental setup limited temporal response of 11 ps pulsewidth. The resulting 45-GHz bandwidth-efficiency product obtained from these devices corresponds to the best performance reported to date for vertically illuminated Schottky photodiodes. Index Terms—Bandwidth-efficiency, high-speed, in-dium–tin–oxide, photodides, photodetectors, resonant-cavit