Feasibility Study of Semifloating Gate Transistor Gamma-Ray Dosimeter

The feasibility study of semifloating gate (SFG) transistor dosimeter consisting a large area p-i-n diode between floating gate and drain region is described. No bias is applied during irradiation. The SFG is charged via the diode when exposed to gamma rays, and reset with the diode positively biased. A comprehensive device simulation that includes the mechanism of charge collection, the operation of device's threshold voltage (Vth) reading, and the effect of diode dark current have been carried out with sentaurus TCAD. As a result, high linear dependence of the Vth on the absorbed dose of ionizing radiation is observed with a sensitivity of 65.8 mV/Gy, which suggests that this device could be used as a sensitive gamma-ray dosimeter.