FET-based radiation sensors with Er 2 O 3 gate dielectric

Abstract Pre-irradiation device characteristics, gamma radiation response, and possible use in radiation dosimetry have been investigated for MOSFETs with a 100 nm thick Er 2 O 3 gate dielectric. The performance of these novel devices has been compared with that of commercial pMOS dosimeters (RadFETs) with a standard SiO 2 gate oxide of the same thickness. The radiation sensitivity of the Er 2 O 3 is significantly higher than that of SiO 2 , and this is particularly pronounced at lower dose levels. Significantly larger numbers of positive charges are trapped in the Er 2 O 3 dielectric than in SiO 2 during irradiation exposure, resulting in increased threshold voltage shift. After two weeks of room temperature annealing, 11.9% and 24.0% fading have been observed in SiO 2 and Er 2 O 3 samples, respectively. Higher fading for Er 2 O 3 may be related to higher number of shallow traps close to the dielectric/silicon interface. These initial results are promising for the possible use of Er 2 O 3 as a new gate dielectric in pMOS dosimeters. The observed enhancement of device sensitivity can be a milestone for the introduction of the pMOS dosimeters in personal dosimetry applications.