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Viswanathan, C. R.

Publications and source records attributed to Viswanathan, C. R..

3 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Trapping effects in irradiated and avalanche-injected MOS capacitors

The trapping parameters for holes, and for electrons in the presence of trapped holes, have been measured from a set of wafers with different oxide thickness processed under controlled conditions. The trap cross-sections and densities indicate at least three trap species, including an interfacial species, a dominant bulk species which is determined to tail off from the silicon interface, and a third, lower density bulk species that is distributed throughout the oxide.

Bakowski, M.↗
NASA NTRS1976

Model for thickness dependence of radiation charging in MOS structures

The model considers charge buildup in MOS structures due to hole trapping in the oxide and the creation of sheet charge at the silicon interface. The contribution of hole trapping causes the flatband voltage to increase with thickness in a manner in which square and cube dependences are limiting cases. Experimental measurements on samples covering a 200 - 1000 A range of oxide thickness are consistent with the model, using independently obtained values of hole-trapping parameters. An important finding of our experimental results is that a negative interface charge contribution due to surface states created during irradiation compensates most of the positive charge in the oxide at flatband. The tendency of the surface states to 'track' the positive charge buildup in the oxide, for all thicknesses, applies both in creation during irradiation and in annihilation during annealing. An explanation is proposed based on the common defect origin of hole traps and potential surface states.

Viswanathan, C. R.↗