We present a resonant-cavity-enhanced Single Photon Avalanche Diode (SPAD) fabricated on a reflecting siliconon-insulator (SOI) substrate. The substrate incorporates a two period distributed Bragg reflector fabricated using a commercially available double-SOI process. The resonant-cavity-enhanced (RCE) SPAD detectors have peak photon detection efficiencies ranging from 41% at 780nm to 32% at 850nm and time resolution of 35ps full-width at half maximum. Typical dark count rates of 500, 5000 and 100000 c/s were ...