Noise Characterization of a Waveguide-Coupled MSM Photodetector Exceeding Unity Quantum Efficiency

In the field of silicon photonics, it has only recently become possible to build complex systems. As system power constraints and complexity increase, design margins will decrease - making understanding device noise performance and device-specific noise origins increasingly necessary. We demonstrate a waveguide-coupled germanium metal-semiconductor-metal photodetector exhibiting photoconductive gain with a responsivity of 1.76 A/W at 5 V bias and 10.6±0.96 fF capacitance. Our measurements indicate that a significant portion of the dark current is not associated with the generation of shot noise. The noise elbow at 5 V bias is measured to be approximately 150 MHz and the high-frequency detector noise reaches the Johnson noise floor.