Low-noise InGaAs/InP SPAD with photon detection efficiency exceeding 50% at 1550 nm

We designed a high-performance InGaAs/InP single-photon avalanche diode (SPAD) optimized for fiber-based quantum optics applications. Photon detection efficiency (PDE) was enhanced thanks to a thicker InGaAs absorption layer, while dark count rate (DCR) was kept under control through careful adjustment of the double zinc diffusion and the addition of a contacted guard ring structure. Our SPAD exhibits a PDE of 56% at 1310 nm and 51% at 1550 nm, with a DCR of 20 kcps, and a timing jitter of ∼70 ps (FWHM) at 225 K. At lower excess bias (VEX), a PDE of 40% at 1310 nm and 37% at 1550 nm is achieved with a dark count rate of just 3 kcps and a timing jitter of ~ 100 ps (FWHM). When wirebonded to a custom integrated circuit, the afterpulsing probability is ~ 8%, with a gating frequency of 1 MHz and a hold-off time of 1 μs (max count rate is 1 Mcps) at 225 K and VEX = 5 V and dropped below 3% at 10 μs hold-off.