Noise and responsivity of commercial p+n Ge avalanche photodiodes

Commercial p+n Ge APD samples from two manufacturers are shown to have comparable noise and responsivity, characterised by a quantum efficiency at 1.3 ¿m wavelength of 0.7¿0.75, and a bulk leakage current density at 20 C of 2¿3×10¿4 A cm¿2 before avalanche multiplication. Surface uniformity of avalanche gain is much better than on earlier n+p devices of the same diameter (100 ¿m).