Zero-Bias Noise as a Measure of Free-Carrier Energy Relaxation in Photoconductors

We have illuminated a liquid-helium cooled, Hg-doped, Ge photoconductor with 10.6-\ensuremath{\mu}m radiation at power levels varying by a factor of 2000. The noise temperature was constant at 35\ifmmode^\circ\else\textdegree\fi{}K over this range, in spite of a resistance inversely proportional to power. This temperature has been used to infer a value of 0.135 for the ratio of free-carrier energy-loss time to recombination time.