Dose responses of the SiO2 used in radiation sensors in field effect transistor form

Aim: To investigate the structural changes in the SiO2 (silicon dioxide) layer, which is the sensitive region of the RadFET radiation sensors used in the medical field, and to elaborate the impacts of these modifications on electrical characteristics. Methods: Dry oxidation method was used to grow the SiO2 film on n-type Si (100) and SiO2 MOS capacitors were produced by using DC magnetron sputtering. Irradiation was carried out using a 60Co radioactive source at a dose range of 1 kGy-50 kGy. XRD (X-ray diffraction) results showed that no crystalline structure was formed in the studied dose range. Results: The results obtained from XPS (X-ray photoelectron spectroscopy) showed that Si-Si oxygen deficient bonds were formed in the post-production structure, resulting in the observation of flat band voltage ( ) at negative values. Conclusions: In general, the Si-Si oxygen deficient bond content increased with increasing radiation dose, causing the C-V curve to shift towards larger negative voltage values as desired. The device sensitivity was almost constant after 25 kGy.