Nanoscale metal–semiconductor–metal photodetectors with subpicosecond response time fabricated using electron beam lithography

Metal-semiconductor-metal photodetectors (MSM PDs) with finger spacing and width as small as 25 nm have been fabricated using high-resolution electron beam lithography. Measurements using an electro-optic sampling system show that the fastest detector has a full width at half-maximum response time of 0.87 ps and a 3 dB bandwidth of 510 GHz. Monte Carlo simulation of detector response time is studied and compared with experimental data. Finally, scaling rules for high-speed MSM PDs are proposed.