Precise control of threshold voltage of 4H-SiC JFET for radiation hardened image sensors

In the Fukushima Daiichi nuclear power plants, radiation hardened image sensors have been required for decommissioning. Silicon Carbide (SiC) is expected as semiconductor material enabling the stable operation in high temperature and high radiation environments. Furthermore, by using JFET structure without the gate insulating oxide layer like as MOSFET, we will not be suffering from the reliability issues. In this work, we successfully fabricated SiC-JFETs with normally-on and normally-off characteristics to develop the radiation hardened image sensors. For Normally-off JFETs, the high On/Off ratio and subthreshold slope are achieved at wide range of temperature from 25 to 300 C. Leakage current is remarkably suppressed below detection limit even at 300 C. We must point out that Vth keeps the positive value (normally-off operation) even at 300 C.福島リサーチカンファレンス「廃炉遠隔技術のための耐放射線化と運用技術高度化の展望」に参