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

Abstract

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.