High performance silicon waveguide germanium photodetector

High-performance Ge-on-SOI p?i?n waveguide photodetectors with different sizes were fabricated. The performances, in terms of dark-current, photo current responsivity and 3-dB bandwidth, were well studied. A responsivity of 0.842?A/W at 1550?nm and dark current of 70?nA was measured from this detector at -1?V. The detector with a size of 4??m?10??m demonstrated an optical band width of 19?GHz at -5?V for 1550?nm. Both the experimental results and the finite-difference time domain simulation show that, when the device size is above a certain threshold, the absorption is not sensitively dependent on such designing parameters as the width and length of the photodetector.