Research On Evolution Behavior Of Displacement Defects For 3DK2222A NPN Bipolar Transistor

With a series of ion radiation sources, including 40 Me V Si, 24 Me V Si, 10 Me V Si, 25 Me V O, and 6 Me V C, the evolution of electrical properties and deep level defects for 3DK2222 A bipolar transistors is systematically studied. Based on DLTS and isochronal annealing tests, combined with contrastive analysis, the difference among the displacement damages caused by different radiation sources were studied. The effect of displacement defects on BJT’s electrical properties were revealed.Experimental results show that the rules of different ions radiation influence on electrical properties of 3DK2222 A bipolar transistors are similar. With displacement absorbed dose increases, base current of 3DK2222 A increases, while the collector current remains constant. Moreover, when for displacement absorbed dose for all ions is the same, degradation of drain current is different, while degradation of current gains is the same. Based on DLTS analyses, displacement defect signals caused by five ions is different. For DLTS spectrum of 200 K, signals intensity from the highest to lowest are 25 Me V O, 6 Me V C, 40 Me V Si, 24 Me V Si, and 10 Me V Si, respectively, which is attributed to the difference of displacement absorbed dose of unit ion for five ions. Displacement absorbed dose of unit ion is the more per atom causes, the density of interstitial atoms and vacancies is the more, leading to the increase of recombination, and then the decrease of remainder stable defects.Based on the annealing experiments, the evolution of displacement damage defects induced by five ions were analyzed. It is found that 40 Me V Si can caused part of V3 and V4 defects, and then transferring to double vacancies and single vacancy when annealing temperature is low(340K). 24 Me V Si can only produce V3, V4 defects. 10 Me V Si can produce high density of cascade vacancies V2*, which begins to anneal at 400 K. 25 Me V O leads to a large number of V3, V4 defects and oxide interstitial atoms. That is the result of the existence of VO defects at a high temperature(625 K). 6 Me V C can only produce V2(-/0) defects, and they are to transfer to V2 O defects in the annealing at 500 K.Comparing the evolution of defects and the annealing of electrical properties for the irradiated BJTs by five ions, it is believed that deep level defects influence mainly drain current, current gain is little influenced by VO defects and mainly influenced by double vacancies V2(-/0) and V2 O defects.