Guard-ring free InGaAs/InP single photon avalanche diodes for C-band quantum communication

We present a guard-ring free InGaAs/InP single photon avalanche diode with 20 μm diameter for the optical C-band. At 225 K, 25.6 μs dead time and 17% detection efficiency, the dark count rate is 3 kcps with 0.5% afterpulsing probability. This corresponds to a quantum bit error rate of about 1.2% for 625 MHz timebin-phase BB84 QKD over 125 km.