Characteristics of a pMOSFET suitable for use in radiotherapy

The paper describes dose response and signal fading of Al-gate p-channel (metal oxide semiconductor field effect transistors) MOSFETs in the range of gamma radiation doses used in radiation therapy. MOSFETs with thicknesses of the gate oxide layer of 1 μm and 400 nm were used. The response was characterized by the threshold voltage shift and was studied as a function of the absorbed dose and time after irradiation. The dosimeters with the 1-μm-thick oxide layer can be effectively used for measuring doses in the 0.1–5 Gy range. The dosimeters with 400-nm-thick oxide layer are suitable for measuring doses above 5 Gy. Both types of the dosimeters retain dosimetric information for long periods of time.

► The response of pMOS dosimeters was investigated for doses from 0.1 to 35 Gy.
► The linear dependence between threshold voltage shift and dose was confirmed.
► For doses from 0.1 to 5 Gy dosimetric information was preserved for several days.