Near-Infrared p-i-n Ge-on-Si Photodiodes for Silicon Integrated Receivers

We investigate and characterize p-i-n near-infrared photodiodes fabricated in Ge-on-Si by reduced-pressure chemical vapor deposition, a technology compatible with silicon processing. The detectors exhibit remarkably low dark current densities of 1 mA/cm
²
at unity reverse bias and high responsivities of 200 mA/W at 1.55 mum. We evaluated their small-signal resistance, capacitance, and bandwidth as well as eye-diagrams at 2.5 and 10 Gbit/s .