The Mechanism Of Dose-rate Switching Method For ELDRS Effect Of GLPNP Transister

In this work,60Co-? source was used as the irradiation source for the gated lateral PNP transistor(GLPNP).The irradiated experiments was carried out at 100 rad /s,10mrad/s and dose-rate switching method respectively.Electrical parameters of gated lateral PNP transistor are measured using a semiconductor characterization system.Based on the electrical degradation and gate sweep technology,the feasibility of the switching-dose method was verified and its acceleration mechanism was explored.The results show that the current gain of the transistor irradiated at 10mrad/s is more severe degradated than that of irradiated at 100 rad/s.The analysis of the basic micro-defects shows that the oxide charge concentration generated at the transistor irradiated at 10mrad/s is less than that of irradiated at 100 rad/s,but its interface state concentration is more.Moreover,under the condition of low dose rate irradiation,the growth rate of interface state concentration is faster,resulting in a more rapid degradation,which causes the electrical performance degradation of the transistor to be more serious.The results show that the ELDRS effect is mainly caused by the competition between the trapping of hole by the trapping trap and the recombination of hole in composition center of the oxide layer.For the sample irradiated at dose-rate switching method,although different doses of irradiation at high dose rate were performed in the previous period,when the irradiation dose switched to low dose rate,the damage trend of the device become s similar to that of the sample irradiated at pure low dose rate.But we can also find that the degradation of the GLPNP bipolar transistor irradiated at the switched dose-rate is slightly lower than that of the sample irradiated at low dose rate.that is,the switching dose rate method realized acceleration at a degree.But the pre-irradiation under high dose rate has influence to the low dose rate irradiation.which resulting in a accelerated annealing-rate of radiation-induced defects and a smaller degradation.