A method for measuring ionizing radiation dose by analyzing hybrid-π parameters of transistors

摘要

Transistors have been used as a detector for ionizing radiation dose monitoring, even if such a device was not manufactured for such purpose. For more than 40 years, MOSFET has been used as a dosimeter in radiotherapy beams. The bipolar junction transistor (BJT) can also be used as a dosimeter in ionizing radiation beams, however the method for measuring the radiation dose is different from MOSFET. In any case, the physical quantity measured when using a transistor as a dosimeter always correlates with a variation of electric current or voltage. The purpose of this paper is to present a method for measuring the ionizing radiation dose by a process of measuring the variation of transistor hybrid-π parameters. To present the method we used two types of transistors, MOSFET and BJT, and also the two types of polarity: N and P-channel for MOSFET; NPN and PNP type for BJT. In both transistors there are hybridπ parameters that the radiation beam does not significantly disturb its value. However, It has been observed in the results that there is at least one parameter of the transistor hybrid-π model that is changed by the exposure of the device to the ionizing radiation beam.