Ionization radiation induced degradation of MOSFET channel frequency response

A model is presented for the frequency response degradation of metal-oxide-semiconductor field-effect transistors (MOSFETs) exposed to ionizing radiation. It is shown that response degradation can be predicted by monitoring a single parameter, the gate-to-channel time-constant tau /sub GC/, which is highly sensitive to the density of interface traps at the silicon-insulator interface. The value of tau /sub GC/ and its degradation with radiation dose are directly obtained by measuring the small signal impedance of a MOSFET. The measurement technique used enables the extraction of effective mobility of the inversion layer. Frequency response characteristics of two types of MOSFETs, fabricated using two different gate-insulator technologies and exposed to a total dose of 1 Mrad (Si), are compared.<
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