Summary 500 words
After being irradiated with a gamma source up to 10 MRad, thick oxide DEPFET-like transistors have shown a negative voltage shift of 18 - 23 V, reduced to 14 - 20 V after 28 days of annealing at room temperature. This voltage shift is foreseen to be compensated by changing the operation voltage in the switcher, the steering chip used for DEPFET matrix operation. In order to reduce the voltage shift therefore the complexity of this chip a new thin oxide technology is currently being developed in the DEPFET collaboration showing promising results in the first tests.
In the present work, in order to study the effect of radiation damage on DEPFET-like transistors, several parameters as threshold voltage, gain and sub-threshold zone were monitored during the irradiation. The influence of manufacturing and operational parameter such as doping, channel dimension and biasing voltage were also studied. The irradiation took place in 11 steps during the summer 2010 in the Radiation Physics Laboratory of the Santiago de Compostela University using a radioactive source of 2080 Ci of activity allowing a dose of 11 krad/h.