Análise de parâmetros π-híbridos de um MOSFET com encapsulamento TO-220 sob feixes de raios X para diagnóstico médico

In recent decades, MOSFET has been used as an ionizing radiation detector, mainly in dosimetric applications in radiotherapy. The basis of the method of operation of such an electronic device in radiotherapy consists of measuring the variation of the threshold voltage of the MOSFET, since this electrical parameter is proportional to the dose of ionizing radiation deposited in the device. The objective of this work is to present a method of measuring the dose of ionizing radiation by measuring the variation of some hybrid-π parameters of a MOSFET. Only transistors with TO-220 encapsulation and two different polarity types were analyzed: n channel and p channel. The devices were submitted to X-ray beams whose energy is in the range applied to medical diagnosis. The results showed that the hybrid-π parameters transconductance ( g m ) and the C gd capacitance varied with the accumulated dose up to the limit of 100 Gy.