Investigation of RadFET response to X-ray and electron beams

• Published in: Applied radiation and isotopes 2017-09, Vol.127, p.156-160
• Main Authors: Yilmaz, E., Kahraman, A., McGarrigle, A.M., Vasovic, N., Yegen, D., Jaksic, A.
• Format: Article
• Language: English
• ISSN: 0969-8043; 1872-9800
• DOI: 10.1016/j.apradiso.2017.06.004

The irradiation response of Radiation Sensing Field Effect Transistor (RadFET), also known as MOSFET/pMOS dosimeter, to high energy X-rays and electron beams was investigated. The threshold voltages before and after irradiation were measured and the trap densities in the gate oxide and oxide/silicon interface of the RadFETs are evaluated. The RadFETs were irradiated with 6MV X-rays, and 10 and 18MeV electron beams emitted from a Linear accelerator (LINAC). Linear and non-linear fits to experimental results showed that after an initial linear response up to several Gy, deviation from the linearity occurred due to electric field screening by the radiation induced oxide trapped charges. The radiation-induced fixed traps (FTs) and switching traps (STs) were analysed and the FT density was found to be higher than the ST density for all beam types and doses. The radiation response, fading characteristics, and variation of the trapped charges of the RadFETs showed similar behaviour in tests. •Radiation sensitivities of the RadFETs for radiotherapy beams were investigated.•Fixed and switching traps were determined using midgap and charge pumping techniques.•Fixed traps give dominant contribution to the threshold voltage shift of the RadFETs.•All results obtained from X-rays and electron beams exhibit similar trends.•The short term fading of the RadFETs was investigated.