Abstract
Recently, the semiconductor devices processing has been rapidly developed. The detectors using semiconductor devices have been used for radiation monitors. The radiation detector for high dose range is very expensive and needs export from abroad. Consequently, the purposes of this thesis are to find the radiation detectors using the commercial semiconductor devices and study electric characteristics of those devices. This article focuses on applications of the high range radiation monitoring during accident of nuclear power plant. Therefore, electric characteristics of the semiconductor devices were studied through the experiments for achieving cheaper radiation detectors and monitors. This dissertation comprises three studies. It is successfully found in the first study that the Power Metal-Oxide-Semiconductor-Field-Effect-Transistor (MOSFET) devices can be used for the high range dosimeters. Due to the interface trap charges increased by radiation interaction, we can measure the change of pumping current in corresponding with interface charges induced by radiation exposure dose. We also find that the Power MOSFETs are suitable to be used in a high temperature and high radiation dose environment of the Nuclear Power Plant. The second study is radiation measurement of pulse mode operation. Normally, PIN photodiode is used to be a pulse mode radiation detector by means of charges generation in its P-I-N structure under radiation interaction. We find that the Power MOSFET device exists a parasitic n+/ p+/ n-/ n+ device from the source to the drain, which is similar to the P-I-N structure. To be used in high radiation dose environment, we find that the Power MOSFET devices have more advantage than the PIN photodiodes. The third study is radiation measurement of current mode operation. It is successfully found that the Solar Cell devices can be used for the high range radiation measurement. As the PN junction of the device is exposed by radiation, the electron-hole pairs are generated by energy deposited from gamma-rays and they are easy to escape from energy band. Thus, a large amount of electron-hole pairs generated by high radiation can produce a measurable current. The experimental result of current to exposure dose rate is 5~8E-11 A/(rad/hr) approximately. We also develop a current amplifier to build a radiation monitor. The radiation measurement calibration has been performed on the monitor, which was proved to have a very good linearity in logarithm scale. Hence, Solar Cell detector and monitor can be used for the high range radiation measurement during accident of nuclear power plant.