Ge-on-Si SPAD Sensors

Gerald Buller leading Single-Photon Group in Heriot Watt University, UK, presents Ge-on-Si SPAD devices which are supposed to solve the low IR detection efficiency problems of the regular Si-based SPADs:

Recently, the group has published a Nature paper "High performance planar germanium-on-silicon single-photon avalanche diode detectors" by Peter Vines, Kateryna Kuzmenko, Jarosław Kirdoda, Derek C. S. Dumas, Muhammad M. Mirza, Ross W. Millar, Douglas J. Paul, and Gerald S. Buller:

"In the short-wave infrared, semiconductor-based single-photon detectors typically exhibit relatively poor performance compared with all-silicon devices operating at shorter wavelengths. Here we show a new generation of planar germanium-on-silicon (Ge-on-Si) single-photon avalanche diode (SPAD) detectors for short-wave infrared operation. This planar geometry has enabled a significant step-change in performance, demonstrating single-photon detection efficiency of 38% at 125 K at a wavelength of 1310 nm, and a fifty-fold improvement in noise equivalent power compared with optimised mesa geometry SPADs. In comparison with InGaAs/InP devices, Ge-on-Si SPADs exhibit considerably reduced afterpulsing effects. These results, utilising the inexpensive Ge-on-Si platform, provide a route towards large arrays of efficient, high data rate Ge-on-Si SPADs for use in eye-safe automotive LIDAR and future quantum technology applications."