The empirical dependence of radiation-induced charge neutralization on negative bias in dosimeters based on the metal-oxide-semiconductor field-effect transistor

Abstract

The dependence of radiation-induced charge neutralization ͑RICN͒ has been studied in metal-oxide-semiconductor field-effect transistor ͑MOSFET͒ dosimeters. These devices were first exposed to x rays under positive bias and then to further dose increments at a selection of reverse bias levels. A nonlinear empirical trend has been established that is consistent with that identified in the data obtained in this work. Estimates for the reverse bias level corresponding to the maximum rate of RICN have been extracted from the data. These optimum bias levels appear to be independent of the level of initial absorbed dose under positive bias. The established models for threshold voltage change have been considered and indicate a related nonlinear trend for neutralization cross section N as a function of oxide field. These data are discussed in the context of dose measurement with MOSFETs and within the framework of statistical mechanics associated with neutral traps and their field dependence.

Extension of the measurement range of MOS dosimeters using radiation induced charge neutralization

“…This phenomenon, known as radiation induced charge neutralization (RICN) [24]- [26], is possibly due to the neutralization of trapped holes by electrons generated by irradiation. When the electrical field in the oxide is inverted after switching the gate bias , the radiationgenerated electrons are accelerated towards the silicon interface instead of moving towards the gate.…”

“…On the other hand, the dependence of sensitivity with VBIAS was not investigated in this work. A complete optimization of the biasing technique should also include this dependence to maximize the overall sensitivity [26], [31], [32].…”

Application of p-Channel Power VDMOSFET as a High Radiation Doses Sensor

“…A fraction of these holes is trapped in the oxide, leading to accumulation of positive oxide charge. The trapping rate depends on the applied field, number of empty traps and their capture cross section [26], [27]. The interface traps generation is commonly accepted to be associated with intermediate processes involving holes capture, release and migration of hydrogen ions in the oxide [28], [29].…”

The effects induced by the gamma-ray responsible for the threshold voltage shift of commercial p-channel power VDMOSFET

“…A field-de pend ant frac tion of them escapes the ini tial re com bi na tion, lead ing to a fur ther rapid elec tron move ment to ward the gate elec trode, while the holes move slowly to ward the SiO 2 /Si in terface. A part of these holes is trapped in the ox ide, leading to the ac cu mu la tion of pos i tive trapped charge, whose trap ping rate de pends on the gate bias (the ap -plied field), the num ber of empty traps and their capture cross-sec tion [11][12][13]. The in ter face trap gen er ation is com monly ac cepted to be as so ci ated with the in ter me di ate pro cesses in volv ing the holes cap ture, the re lease and the mi gra tion of hy dro gen ions in the ox ide [14,15].…”