High bandwidth, high responsivity waveguide-coupled germanium p-i-n photodiode

A novel waveguide-coupled germanium p-i-n photodiode is demonstrated which combines high responsivity with very high. 3 dB bandwidth at a medium dark current. Bandwidth values are 40 GHz at zero bias and more than 70 GHz at -1 V. Responsivity at 1.55 mu m wavelength ranges from 0.84 A/W at zero bias to 1 A/W at -1 V. Room temperature dark current density at -1 V is about 1 A/cm(2). The high responsivity mainly results from the use of a new, low-loss contact scheme, which moreover also reduces the negative effect of photo carrier diffusion on bandwidth. (C) 2015 Optical Society of America