Fabrication and characterization of the stacked nuclear radiation sensing field effect transistors (NürFETs) with high-K

NürFETs are integrated ionizing radiation sensors that operate on the principle of converting radiation-induced threshold voltages into absorbed doses, which are commonly used to measure absorbed doses in spacecraft, military, high energy physics laboratories, and radiotherapy. However, one of the major drawbacks of the conventional NürFETs is the inability to sense and detect very low radiation doses at the mGy range, which are needed for personal dosimeter and low radiation environments. In this study, the NürFETs with a stacked structure, a design method, where NürFETs are coupled in a stacked structure (stacked-NürFETs) were fabricated. The stacked-NürFETs structure approach was designed to improve the sensitivity of single NürFETs and the performance of the stacked-NürFETs as radiation sensors were investigated and discussed. The pre-irradiation electrical characteristics of the device were evaluated, and the initial threshold voltages (Vth) have shifted to larger negative voltage values, which are proportional to the number of the NürFETs increased in the stacked-NürFETs structure. The post-irradiation electrical characteristics of the device were obtained, and their responses to irradiation and possible usages in radiation dosimetry have been investigated and discussed. The results demonstrate that the sensitivities of the stacked-NürFETs are directly proportional to the number of sensors used in the stacked-NürFETs structure.