Al0.8Ga0.2As Avalanche Photodiodes for Single-Photon Detection

We report Al
_0.8
Ga
_0.2
As recessed-window single-photon avalanche photodiodes with high internal single-photon detection efficiency and low dark count probability. External quantum efficiency was increased by a factor of 2 at λ = 405 nm. Annealing in arsine with hydrogen carrier gas reduced the dark count probability by a factor of 100, to ~10
^-6
/gate with a ~5 ns gate, at room temperature. The activation energies of primary carrier traps, which give rise to afterpulsing, are extracted in a temperature range from 150 to 200 K.