Low Dark Count Rate and Low Timing Jitter InGaAs/InP Single-Photon Avalanche Diode

We describe the design and characterization of a new InGaAs/InP Single-Photon Avalanche Diode (SPAD) for single-photon detection at 1.55 µm with high detection efficiency, low noise and low timing jitter. The design and fabrication have been optimized to reduce the defects (responsible for dark counts and afterpulsing). Zinc diffusion is a key step and we optimized the profile, pattern and reactor parameters to achieve uniform sensitivity in the active area, low noise and low timing jitter. The active area diameter of the device here described is 25 µm and no floating guard rings are present. It is operated in gated mode, with passive quenching, for the characterization. The dark count rate is in the order of few kilo-counts per second at 225 K and 5 V of excess bias. The photon timing resolution, measured as the full-width at half maximum of the response to a 20 ps pulsed laser, is about 90 ps, with a clean exponential tail whose time constant is about 60 ps. The photon detection efficiency is about 30% at 1550 nm. These specifications make our InGaAs/InP SPAD a good candidate for advanced time-correlated single-photon counting applications at wavelengths up to 1700 nm