Dark current noise characteristics and their temperature dependence in germanium avalanche photodiodes

Dark current noise causes degradation in the signal-to-noise ratio (SNR) in optical receiver performance. The shot noise power induced by multiplied dark current was measured for germanium avalanche photodiodes (Ge-APD's). The noise power has a different excess noise factor F
d
from that for photocurrent multiplication noise; F
d
was
M_{p}^{1.0}
for a p+-n type Ge-APD and
M_{p}^{0.9}
for an n+-p type APD where M
p
is the photocurrent multiplication factor. The dark current noise has a strong frequency dependence at frequencies lower than 300 MHz. The temperature dependence of the noise was also measured.