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Radiation-induced charge transport and charge buildup in SiO/sub 2/ films at low temperatures

Conference · · IEEE Trans. Nucl. Sci.; (United States)
OSTI ID:7307264

Studies of the temporal, temperature, and electric-field dependences of radiation-induced charge transport have been performed for radiation-hardened SiO/sub 2/ films. At room temperature for high applied fields, nearly all electrons and holes generated in the oxide by a pulse of ionizing radiation (5-keV electrons) drift to the interfaces, whereas at low temperatures only electrons contribute to observed transport for relatively low fields. Below approximately 130/sup 0/K at high fields, field-induced emission of trapped holes occurs, giving rise to collection within seconds of a significant fraction of the total number of holes generated. The present hole transport data are accounted for quite well in terms of a multiple-trapping model with a spread in trap levels ranging from approximately 0.3 to approximately 0.5 eV from the valence band. Comparison with the stochastic hopping transort model is made and that model is found to be less satisfactory in explaining these data. Charge buildup was examined in a Co/sup 60/ environment and it is demonstrated that oxides exhibiting radiation tolerance at room temperature display severe radiation-induced changes at 77/sup 0/K. It is also demonstrated that low-temperature charge buildup problems can be alleviated either by employing an ion-implanted oxide or by applying a relatively high field to the oxide during irradiation.

Research Organization:
Northrop Research and Technology Center, Hawthorne, CA
OSTI ID:
7307264
Journal Information:
IEEE Trans. Nucl. Sci.; (United States), Journal Name: IEEE Trans. Nucl. Sci.; (United States) Vol. NS-23:6; ISSN IETNA
Country of Publication:
United States
Language:
English