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Dependence of interface-state buildup on hole generation and transport in irradiated MOS capacitors

Conference · · IEEE Trans. Nucl. Sci.; (United States)
OSTI ID:7307245

In a prior publication, Winokur and Sokoloski reported that the nature and magnitude of the buildup of interface states in MOS capacitors under positive bias was the same for both penetrating Co/sup 60/ ..gamma.. and nonpenetrating 10.2 eV uv radiation. They suggested that the buildup of interface states in MOS capacitors subjected to highly ionizing radiation was not due to the direct interaction of radiation at the interface or to a structural modification of the SiO/sup 2/ layer, but resulted from the production of electron-hole pairs in the insulator and the subsequent transport of holes to the interface. In the work reported on in this paper, the uv-Co/sup 60/ study was repeated (adding negative bias) on another set of thermally grown oxides and the interface-state density was monitored as a function of time from 40 ms to 400 s following a 4-..mu..s electron pulse using a fast C-V technique. From the results of the latter experiment, it is reported that in addition to hole transport to the interface, some slow (relative to the hole transport time) interaction of the holes in the interface region appears to be responsible for the buildup of interface states. In addition, in both the uv-Co/sup 60/ study and the interface-state density with time study, the effects of lateral inhomogeneities were separated from interface states by measuring the frequency dependence of the C-V traces and by measuring the Gray-Brown shift between room temperature and liquid nitrogen temperature. It is shown that all three irradiations, uv, Co/sup 60/, and e-beam, produce interface states. (WHK)

Research Organization:
Harry Diamond Labs., Adelphi, MD
OSTI ID:
7307245
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