Recombination studies on gamma-irradiated n-type silicon

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Abstract
Results of a detailed investigation of recombination in phosphorus‐doped Co60 γ‐irradiated n‐type silicon are reported. An analytical procedure is employed which allows, in principle, a complete and unambiguous determination of parameters associated with recombination centers. Properties of two recombination centers are determined. The level most important at low excess densities is determined to be 0.40 ±0.015 eV from the conduction band. cn varies as exp(0.06±0.015eV/kT), and cp varies as exp(0.03±0.015eV/kT). The capture‐probability ratio cp/cn varies from 8 ± 1 at 303°K to 9.5 ± 1 at 370°K. The level dominant at high excess densities is placed at 0.21 ± 0.03 eV below the conduction band with cn ∼exp(0.01±0.01eV/kT) and cp ∼exp(−0.05±0.03eV/kT). The corresponding capture probability ratio, cp/cn, varies from ∼5.6 at 303 °K to ∼8 at 370 °K. Based upon dependence on phosphorus concentration and annealing behavior, the deeper level appears to belong to the E center. There is some evidence that the other level is also associated with phosphorus‐containing defects.