High-speed high-efficiency resonant cavity enhanced photodiodes

In this paper, we review our research efforts on RCE high-speed high-efficiency p-i-n and Schottky photodiodes. Using a microwave compatible planar fabrication process, we have designed and fabricated GaAs based RCE photodiodes. For RCE Schottky photodiodes, we have achieved a peak quantum efficiency of 50% along with a 3-dB bandwidth of 100 GHz. The tunability of the detectors via a recess etch is also demonstrated. For p-i-n type photodiodes, we have fabricated and tested widely tunable devices with near 100% quantum efficiencies, along with a 3-dB bandwidth of 50 GHz. Both of these results correspond to the fastest RCE photodetectors published in scientific literature

Fabrication of High-Speed Resonant Cavity Enhanced Schottky Photodiodes

Abstract — We report the fabrication and testing of a GaAsbased high-speed resonant cavity enhanced (RCE) Schottky photodiode. The top-illuminated RCE detector is constructed by integrating a Schottky contact, a thin absorption region (InHXHVGaHXWPAs) and a distributed AlAs–GaAs Bragg mirror. The Schottky contact metal serves as a high-reflectivity top mirror in the RCE detector structure. The devices were fabricated by using a microwave-compatible fabrication process. The resulting spectral photo response had a resonance around 895 nm, in good agreement with our simulations. The full-widthat-half-maximum (FWHM) was 15 nm, and the enhancement factor was in excess of 6. The photodiode had an experimental setup limited temporal response of 18 ps FWHM, corresponding to a 3-dB bandwidth of 20 GHz. Index Terms—High-speed circuits/devices, photodetectors, photodiodes, resonant caity enhancement, Schottky diodes