P-channel MOSFET as ionizing radiation detector.

In this study, the authors examine the responses of radiation-sensitive p-channel MOSFETs to irradiation and subsequent annealing at room temperature and higher temperatures to investigate their use as a dosimeter for measuring ionizing radiation. The response of these transistors to radiation was monitored based on the shift in the threshold voltage as a function of the absorbed dose of radiation. The results showed that the shift in the threshold voltage depended on the densities of traps formed during exposure to ionizing radiation in Si and at the Si-SiO2 interface on which the charges were captured. We then analyzed the influence of these traps on the characteristics of the MOSFETs, and examined the influence of the gate bias, thickness of the gate oxide, energy of the ionizing radiation, and low doses on shifts in the threshold voltage. Moreover, we annealed the irradiated MOSFETs to determine their ability to preserve a certain dose of radiation over a long period as well as their potential for reuse. We explored the possibility of using commercial p-channel MOSFETs built into various electronic systems as sensors and dosimeters for measuring ionizing radiation. The results showed that they have approximately the same characteristics as radiation-sensitive MOSFETs with 100-nm-thick oxide layers.