High-detection efficiency and picosecond timing compact detector modules with red-enhanced SPADs

In the last years many progresses have been made in the field of silicon Single Photon Avalanche Diodes (SPAD) thanks to the improvements both in device design and in fabrication technology. Particularly, the Dipartimento di Elettronica e Informazione of Politecnico di Milano and the CNR-IMM of Bologna have been in the forefront of this research activity by designing and fabricating a new device structure enabling the fabrication of SPADs with red enhanced photon detection efficiency. In this paper we present a compact photon counting and timing module that fills the gap between the high temporal resolution and the high detection efficiency systems. The module exploits Red-Enhanced SPAD technology to attain a Photon Detection Efficiency (PDE) as high as 37 % at 800 nm (peak of 58 % at 600 nm) while maintaining a temporal resolution of about 100 ps FWHM, even with light diffused across the whole active area. A thermo-electric cooling system guarantees a noise as low as few counts per second for a 50 mu m diameter SPAD while a low threshold avalanche pick-up circuit assures a limited shift in the temporal response.