Electron injection into p‐type silicon at 76°K has been observed to reduce the lifetime degradation rate due to 60Co gamma irradiation at 76°K. By comparing isochronal annealing data between 76° and 300°K with similar data obtained by Watkins in EPR studies, the lifetime degradation at 76°K is seen to be due primarily to recombination through vacancies. Since the activation energy of motion of silicon vacancies is known to depend strongly on charge state, the injection‐stimulated reduction in degradation rate at 76°K has been related to vacancy reordering which occurs when the injected electron density is sufficiently large to modify the vacancy charge state from neutral (mobile above 160°K) to negative (mobile above 60°K). Quantitative estimates of the vacancy‐reordering rate in the presence of excess electrons show this model to be consistent with the observed phenomena.

Topics
Electron density, Leptons, Chemical elements, Activation energies
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If the vacancy behaved as a normal recombination center, such as Au in silicon, the ratio σn/σp should be approximately 10−2→10−1 at 76 °K [
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H. J.
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6.
Similar Co60 irradiations of n‐type silicon yield a damage rate at 76 °K not greatly different than for p type (in the absence of injected minority carriers). Injection during irradiation in n type does not appreciably alter its damage rate at 76 °K; however, it does greatly reduce the fraction of damage which recovers between 76 ° and 300 °K from that seen in the noninjection case.
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© 1965 The American Institute of Physics.
1965
The American Institute of Physics
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