Experimental evidence and modeling of non-monotonic responses in MOS dosimeters

Abstract

The evolution of the threshold voltage of MOS dosimeters during irradiation under switched bias is investigated with the aim of using the sensors with a new biasing technique. The devices response to a bias change does not only depend on the instant threshold voltage and bias, and may lead to non-monotonical behavior under fixed bias following the switch. This work shows experimental evidence for this effect and presents a simple model based on oxide charge buildup and neutralization. The proposed model reproduces the experimental data assuming the existence of two types of hole traps in the oxide. Physical interpretations of the results are discussed.