Room temperature quantum key distribution characteristics of low-noise InGaAs/InP single-photon avalanche diode

InGaAs/InP single-photon avalanche diode (SPAD) with small active diameter and backside microlens was fabricated and its dark count and after-pulse noises were characterized. In addition, by optimizing multiplication layer and reducing the active diameter, high photon detection efficiency (PDE) was achieved as well as suppressed dark count probability (DCP) and after-pulse probability (APP) near room temperature. The gated Geiger-mode characteristics of SPAD were investigated with the gate amplitude of 6.6 V and repetition frequency of 10 MHz. Superior single-photon detection characteristics as PDE of 20.9%, DCP of 1.02 × 10 –5 and APP of 0.8% were observed at the operation temperature of + 20 °C. It is a promising result that allows compact and low-cost detector module for quantum key distribution system with simple cooling apparatus.