RADIATION DAMAGE STUDIES OF SILICON PHOTODETECTORS AND MAGNETIC DEVICES.
Final rept. 15 Oct 66-14 Oct 67,
MITHRAS CAMBRIDGE MASS
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The effects of a steady state radiation environment of high energy electrons on a magnetic bolometer device, on silicon photodetectors, and on silicon, were studied. A practical form of a magnetic bolometer which employs a metamagnetic material was developed and reduced to practice. Irradiation by 1 Mev electrons had the major effect of broadening the temperature region over which the Mitherm operates. The value of detectivity measured suggested that with proper sample selection and sample engineering, detectivity values approaching the theoretical limit could be obtained. Radiation effects on an intrinsic silicon photoconductor device were carried out as a function of noise, responsivity, detectivity, DC resistance, and time constant. While the responsivity, noise, and DC resistance increased upon exposure to 1 Mev electrons, the time constant decreased and the detectivity remained nearly constant. This evidence suggests that the total number of free carriers decreased upon irradiation which is consistent with the results of other workers. The problems associated with the observation of paramagnetic centers in silicon brought about by 1 Mev electron irradiation were evaluated. As a result of preliminary experiments and consultation with other workers, a balanced bolometer ESR spectrometer operating at liquid hydrogen or liquid neon temperatures is needed. A Dewar was designed and built for the purpose of maintaining the sample at a constant temperature during the irradiation outside the ESR cavity and after moving the sample into the cavity for subsequent study. Author
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