32 GHz metal-semiconductor-metal photodetectors on crystalline silicon

Interdigitated metal-semiconductor-metal (MSM) photodetectors with 1.2 μm finger spacing and 0.8 μm finger width were fabricated on crystalline Si substrate. The devices are transit time limited, exhibiting a measured full width at half maximum response time of 14 ps and a 3-dB bandwidth of 32 GHz. Monte Carlo simulations of Si MSM photodetector response time and bandwidth agree with experiments and predict that if the finger spacing of the Si MSM photodetectors is reduced to 25 nm, the response time can decrease to ∼1 ps and the bandwidth can increase to 440 GHz.