Differential receivers with highly -uniform MSM Germanium photodetectors capped by SiGe layer

Waveguide integrated MSM (metal-semiconductor-metal) Germanium (Ge) photodetectors (PDs) with a SiGe capping layer were exploited for silicon photonics integration. Under optimized epitaxial growth conditions, the capping layer passivated the Ge surface, resulting in sufficiently low dark current of the PDs. In addition, the PDs exhibited a narrower distribution of the dark current than PDs with a Si capping layer, probably due to the lower surface leakage current. Low-noise differential receivers with uniform MSM Ge PDs exhibiting 10 Gbps data transmission were realized.