Copper-doped germanium detectors

Background limited operation of copper-doped germanium detectors has been obtained for a background as low as 10
^-11
watts (5 × 10
³
photons/second) in the 8-12 µ region. The temperature dependence of the observed responsivity for detectors, each containing the same copper concentration but having different donor concentration does not agree with any of the usual theories involving the free hole velocity, mobility, or capture cross section.