A Substrate Isolated CMOS SPAD Enabling Wide Spectral Response and Low Electrical Crosstalk

In this work we present a substrate isolated single photon avalanche diode designed and fabricated in 180 nm CMOS technology. Substrate isolation is ensured by design to enable lower electrical crosstalk and to ease circuit integration. The presented device achieves wide spectral sensitivity enabling greater than 40% photon detection probability from 440 to 620 nm wavelength at 10 V excess bias. For a 12 μm active diameter, the dark count rate of the device is 17 Hz and 1.45 kHz at 2 and 10 V excess bias, respectively, while the after pulsing probability is less than 0.3% with 300 ns dead time at 10 V excess bias, and timing jitter was 70 ps (full width at half maximum) when using 405 nm wavelength laser.