Effect of Injection Level on Carrier Lifetime in Neutron-Irradiated Germanium

The dependence of minority carrier lifetime on injection level was analyzed to yield recombination center parameters for neutron-irradiated germanium. The results are an improvement over data obtained by other methods because they eliminate a possible dependence of capture probability on temperature, and are more sensitive to energy level position. Six n-type specimens doped with arsenic and antimony in the resistivity range from one to twenty ohm-cm were studied. The results reveal a recombination center level of Er - Ev = 0. 34 ± 0.01 eV for antimony-doped germanium and Er - Ev = 0.335 ± 0.01 eV for arsenic-doped germanium. The dependence of lifetime on injection level for high excitation demonstrated the appropriateness of the model which includes the effect of a level of Ec - Er ~ 0.2 eV.