Study of the subthreshold swing of a pMOSFET as a dosimetric parameter

A study of the degradation of the subthreshold swing in a general-purpose pMOSFET is carried out to evaluate its use as a dosimetric parameter. Its reliability in terms of sensitivity, linearity, and reproducibility is experimentally tested and compared with the threshold voltage shift under gamma rays from a 60Co source up to 56 Gy, typical in radiotherapy treatments. The dependence of the subthreshold swing as a function of temperature is characterized and modelled as a mean for thermal compensation when used for dose measurement. Very promising results have been obtained for the subthreshold swing as a complementary dosimetric parameter to the threshold voltage for enhancing the confidence of dose verification systems based on MOSFETs.

► pMOS Subthreshold swing analysed as dosimetric parameter.
► Sensitivity, linearity and reproducibility of the response to the radiation.
► Subthreshold swing response comparable to threshold voltage.
► Enhanced reliability for the dose verification of radiotherapy treatments.