P-channel MOSFET as a sensor and dosimeter of ionizing radiation

Abstract

This paper presents a study of MOSFETs as a sensor and dosimeter of ionizing radiation. The electrical signal used as a dosimetric parameter is the threshold voltage. The functionality of these components is based on radiation-induced ionization in SiO 2 , which results in increase of positive charge trapped in the SiO 2 and interface traps at Si-SiO 2 , leads to change in threshold voltage. The first part of the paper deals with analysis of defect precursors created by ionizing radiation, responsible for creation of fixed and switching traps, as well as most important techniques for their separation. Afterwards, the results for sensitive p-channel MOSFETs (RADFETs) are presented, following with results for commercially available MOSFETs applications as a sensors of ionizing radiation.

Spice modeling of ionizing radiation effects in CMOS devices

“…The parameter b, which appears in the equation (21), can have the value b = 0 for the source end of the channel and b = 1 for the drain end of the channel (in accordance with the equations (9) and (10)). However, the main problem in modelling of trapped charges with (21) is the fact that the distribution of surface potential in the channel depends not only on gate voltage, but also on drain voltage V DS due to split of quasi Fermi levels [19].…”

“…After the generation of the electron-hole pairs, some of the pairs are immediately recombined. Since the electron mobility in the oxide is considerably bigger that the hole mobility [15,9], the electrons will be soon swept out of the oxide or the dielectrics, while the holes will move slowly through the oxide to the interface SiO 2 -Si, causing long-term effects of the ionizing radiation. Fig.…”

“…In the equations (9)-(11) the index F relates to the front gate, and the index B relates to the back gate. Recurrent relations (9) and (10) are calculated with the assumption that the difference of Fermi's potentials between the source and the drain is equal to the voltage V DS . Electric potential distribution in the channel through depth, i.e.…”

“…Analysing of test IC circuits on ionizing radiation is quite expensive [7], so the incorporation of ionizing radiation effects in devices compact models used in standard electric circuits simulators is put upon as an alternative. The incorporation of these effects needs the knowledge of physical processes which contribute to emerging of the defects due to ionizing radiation and the impacts which these effects have on the electric characteristics of components in advanced CMOS technologies [8,9]. Numerous existing techniques for modelling these effects in circuit simulators are based on the fixed change of threshold voltage (threshold voltage shift), not considering the special impact which these defects have on the electric characteristics of the transistors [2,[10][11][12].…”

Effect of Temperature and Electrical Modes on Radiation Sensitivity of MISFET Dose Sensors

“…MISFET-based sensors of the total ionizing dose D (TID) have been studied by many investigators [4][5][6][7][8]. Found that radiation sensitivity of sensors depend on electrical modes, structural and technological parameters of MISFET.…”