We report on a waveguide-coupled (WG) vertical Germanium on Silicon (Ge-on-Si) Separate Absorption Charge Multiplication (SACM) Avalanche Photodiode (APD) achieving 3dB-bandwidths of 50 GHz and 30 GHz at an O-band responsivity of 3 A/W and 6 A/W respectively, combined with dark current levels below 50 nA. The experimental measurements are supported by a modeling approach showing how to optimize the SACM-APD charge layer to target high-speed performance.
