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内容記述 |
In recent years, there is a strong demand for semiconductor devices that can be used in high-temperature and high-radiation environments such as nuclear power plants and space explorations. SiC is one of the candidates for base semiconductor of the radiation hardened device. We previously showed radiation resistance of the SiC image sensor is closely realted with quantum efficiency (QE) of 4H-SiC UV photodiodes. As QE would be lowered by an increased defect density at the interface between SiO2 and SiC, an embedded PD is introduced in 4H-SiC CMOS active pixel sensors and irradiated up to 5 MGy. Three types of PDs were fabricated: the non-embedded photodiode (PD1), the shallowly embedded photodiode (PD2), and the deeply embedded photodiode (PD3). These were illuminated with UV light of wavelengths from 240 nm to 370 nm for QE evaluation. After gamma-rays irradiation, QE of the PD2 and PD3 was higher than that of the PD1. For the embedded PD, carriers would have a distance from SiO2/SiC interface, and then the influence of interface levels was reduced. |
