Investigation of the usability of Yb2O3/SiO2 stack gate oxide layer as a sensitive region in MOS-based radiation sensors

In this study, effect of the SiO2 layer to be deposited between Yb2O3 and n-Si on the interface quality, and the usability of the Yb2O3/SiO2 stack gate oxide layer as a sensitive region in MOS-based radiation sensors were investigated. 20 and 36 nm thick-SiO2 layers were grown on the n-Si substrates by thermal oxidation. EBPVD system was used for coating Yb2O3 films. Yb2O3/SiO2/Si structures were annealed at five different temperatures in nitrogen environment. Polycrystalline Yb2O3 films were found to be in the cubic phase. The pre/post-irradiation electrical characteristics of Al/Yb2O3/SiO2(20nm)/n-Si/Al and Al/Yb2O3/SiO2(36nm)/n-Si/Al MOS capacitors were measured at six different frequencies ranging from 50 kHz to 1000 kHz. The 𝑄𝑒𝑓𝑓, 𝜀𝑘, 𝑁𝑖𝑡 values were calculated. The radiation responses of Al/RT-Yb2O3/SiO2(20nm)/n-Si/Al and Al/200 °C-Yb2O3/SiO2(36nm)/n-Si/Al capacitors with the best electrical characteristics were analyzed at 100 kHz and 1 MHz in the 1 – 500 Gy dose range using 60Co source. C-V curves of the Al/RT-Yb2O3/SiO2(20nm)/n-Si/Al and Al/200 °C-Yb2O3/SiO2(36nm)/n-Si/Al capacitors for both frequencies shifted with increasing dose to left and right, respectively. In Al/RT-Yb2O3/SiO2(20nm)/n-Si/Al capacitor, degradation occurred in the radiation response of the device as 𝛥𝑁𝑖𝑡 remained at the same level as 𝛥𝑁𝑜𝑥 in the studied dose range. In Al/200 °C-Yb2O3/SiO2(36nm)/n-Si/Al capacitor, 𝛥𝑁𝑜𝑥 was constantly increasing, while major changes in 𝛥𝑁𝑖𝑡 was not observed with radiation dose. As a result of the research, it was determined that the interface quality improved with SiO2 layer, and it was emphasized that density of the