Recombination Cross Section for Holes at a Singly Ionized Copper Impurity in Germanium

The recombination cross section has been measured for several copper-doped-germanium samples from the decay of the photoexcited-carrier population. Measured carrier lifetimes were sufficiently long to ensure that the photoexcited carriers were in thermal equilibrium with the lattice. The magnitude and temperature dependence of the cross section indicate that recombination occurs via acoustic-phonon emission for excited-state capture, and optical-phonon emission for capture directly into the ground state. Cross sections reported in this work are an order of magnitude larger than those measured from generation-recombination noise.