Low afterpulsing and narrow timing response InGaAs/InP Single-Photon Avalanche Diode

We designed, fabricated and tested a new planar InGaAs/InP Single-Photon Avalanche Diode (SPAD). By optimizing design and fabrication processes, we obtained low afterpulsing and very good timing jitter, with very fast tail. The detector has a separate absorption, charge and multiplication structure, with double p-type Zn diffusion into n-type InP for defining the p-n high-field avalanching junction. The SPAD can be operated at temperatures achievable with thermoelectric coolers mounted in compact packages (like TO-8). When operated in gated mode with 5 V excess bias, the 25 μm active area diameter InGaAs/InP SPAD reaches good performance at 225 K: i) photon detection efficiency of 40% at 1 μm and 25% at 1.55 μm; ii) dark count rate below 100 kcps (counts per second); iii) low afterpulsing allowing to set a hold-off time as short as 1 μs, corresponding to 1 Mcps; iv) timing jitter less than 90 ps (full width at half maximum) and time constant of decaying tail of just 30 ps. Overall this new planar InGaAs/InP SPAD can be exploited in many near-infrared (up to 1.7 μm) applications where low light, wide dynamic range waveforms have to be acquired, e.g. in Time-Correlated Single-Photon Counting (TCSPC) measurements or Time-of-Flight LIDAR applications for eye-safe 3D ranging