The impact of spacer oxide material on the underlapped soi-nfinfet working as charged based radiation sensor

Abstract

— In this work, the influence of the underlap region on the electrical behavior of a SOI-nFinFET transistor has been studied by numerical simulation with the purpose of radiation sensing. The analysis has been performed by evaluating the impact of spacer length, width and spacer oxide material of the underlap region on the On-state current and by studying its sensitivity. The impact of the underlap region on the drain current and, consequently, on the devices’ sensitivity was explained by the analysis of series resistance, the fringing field and electron density. Considering the main impact of radiation in these devices, the study of sensitivity has been also performed taking into consideration the variation of oxide trapped charges den-sity. When applying the transistor to a harsh environment, the underlapped FinFET showed to be a quite respectable radiation sensor, since the results performed with very good sensitiv-ities when using long and narrow spacer oxide with low permit-tivity oxide. With thicker spacer oxide in the underlap region, the charge concentration makes the spreading field high enough to overcome the series resistance effect, which results in a less sensible device. Since underlapped FinFETs have high sensitivity in the On-state current, reaching 200% for SiO2 spacer oxide material and VDS=1V, these devices show to be promising to work as charged based radiation sensor. Two dif-ferent proposals for radiation sensing are presented.