Design of resonant cavity structure for efficient high-temperature operation of single-photon avalanche photodiodes

A novel design of a single-photon avalanche photodiode (SPAD) is proposed based on resonant cavity (RC) structure, and its performance is studied. In the proposed structure, InAlAs/InGaAs distributed Bragg reflectors (DBRs) are employed as top and bottom mirrors and the quantum efficiency (QE) of the absorption region is calculated considering the effect of the RC. Results show that using 12 periods of DBRs as a bottom reflector without incorporation of a top mirror can enhance the QE to about 90% at room temperature. For this RC-enhanced SPAD, a single-photon quantum efficiency (SPQE) is obtained of about 0.35 at T=300 K. For temperatures lower than T=260 K, SPQE is about 1. Results show that although the RC doesn't affect the dark current, for a given SPQE the dark count rate is lower for the RC-SPAD.