輻射敏感場效應電晶體是一種廣泛應用於輻射環境監測的 MOSFET 元件。吸收劑量可透過一個響應函數，將量測到的電壓偏移轉換為氧化層中對應的電離能量沉積來決定。本研究針對所選用之 RADFET 進行分析，並建立一個可同時考慮照射效應與衰退效應（fading）的響應函數，以適用於多種輻射環境條件。 為了納入屏蔽效應與次級粒子生成，本研究採用 Geant4 模擬來分析粒子與材料之間的交互作用，並建構包含儀器幾何結構與周圍介質的完整模型。入射粒子能譜依據范艾倫輻射帶環境設定，包括能量範圍為 0.01–240 MeV 的質子，以及 0.01–10 MeV 的電子，同時考慮電磁與強作用（hadronic）物理過程。模擬結果提供不同入射粒子種類及能量條件下的能量沉積，並進一步從停止作用（stopping power）與線性能量轉移（linear energy transfer， LET）機制進行分析與討論。 在地面實驗驗證方面，本研究使用 221 MeV 質子束進行能量沉積模擬。透過比較預測之臨界電壓偏移與實際量測數據，對響應函數中的五個未知參數進行校準，從而驗證所建立模型的可靠性。此外，本研究亦呈現深空輻射探測任務（DSRP）及其飛行量測資料，以說明該響應函數在實際太空環境中的應用價值。DSRP 在穿越輻射帶期間所取得的數據顯示，RADFET 對質子與電子皆具有足夠靈敏度，顯示其在未來太空任務中的應用潛力。;A radiation-sensitive metal–oxide–semiconductor field-effect transistor (RADFET) is a type of metal-oxide-semiconductor field effect transistor (MOSFET) widely used for radiation environment monitoring. The absorbed radiation dose is determined by converting the measured threshold voltage shift into the corresponding ionizing energy deposited in the oxide layer via a response function. This study investigates the behavior of a selected RADFET and develops a response function that simultaneously accounts for both irradiation and fading effects under various radiation conditions. To incorporate shielding effects and secondary particle generation， a GEometry ANd Tracking (Geant4) simulation framework is employed to model particle–material interactions， including detailed instrument geometry and surrounding media. The incident particle spectra are defined based on the radiation belt environment， consisting of protons in the range of 0.01–240 MeV and electrons from 0.01–10 MeV. Both electromagnetic and hadronic physics processes are considered. The simulation results provide energy deposition under different particle flux conditions， which are further analyzed in terms of stopping power and linear energy transfer mechanisms. For ground-based validation， a 221 MeV proton beam is used to simulate energy deposition. By comparing the predicted threshold voltage shifts with experimental measurements， five unknown parameters in the response function are calibrated， establishing the reliability of the proposed model. Furthermore， the Deep Space Radiation Probe mission and its flight data are presented to demonstrate the practical applicability of the response function in space environments. The in-flight data collected during radiation belt crossings confirm that the RADFET is sufficiently sensitive to detect both proton and electron contributions， highlighting its potential for future space missions.
