Book Description
Abstract: In this work we have designed and fabricated resonant cavity enhanced (RCE) germanium-on-silicon (Ge-on-Si) photodetectors, operating around the 1550 nm wavelength for applications in long-haul communications. Without sacrificing bandwidth, the spectral response of the Ge photodetector is enhanced by fabricating the Ge detector within a Fabry-Perot cavity, where the Ge active region is grown atop one or two-period silicon-on-insulator (SOI) substrates designed for maximum reflectivity (>80%) in the 1300 nm-1600 nm wavelength range. The responsivity of these Ge/SOI RCE photodetectors around 1550 nm is further enhanced by the increased absorption coefficient due to the tensile strain-induced bandgap narrowing effect within the Ge film. Detector bandwidths approaching 13 GHz and quantum efficiencies of nearly 60% have been measured around 1550 nm, which demonstrates the compatibility of these Ge/SOI photodetectors with 10 Gb/s data communication systems. In addition, the measured full-width at half-maximum (FWHM) of the spectral resonant peak is approximately 50 nm, encompassing the entire C-band wavelength range (1528 nm-1565 nm) used in long-haul optical communications, making these high-speed Ge detectors ideal for integration with WDM-based telecommunication systems. To the author's knowledge, these detectors are the fastest, most efficient Ge photodetectors fabricated directly on Si and optimized for 1550 nm operation.
