Evolution of radiation defects in NPN bipolar junction transistors irradiated by 3 MeV protons

In space, energetic proton irradiation produces both ionization and displacement damage in semiconductors and devices served in spacecraft. In order to separate the ionization and displacement damage in bipolar junction transistor (BJT), the electrical degradation and radiation-induced defects were studied during 3 MeV proton irradiation and the annealing process. The current gain degradation shows a nonlinear relationship with the increasing fluence during irradiation. It can be deduced that the proton irradiation produces the ionization/displacement combined damage in NPN BJTs. Ionization and displacement-induced defects are measured by deep level transient spectroscopy (DLTS) during the isochronal annealing. During the isochronal annealing, the ionization-induced defects annealed at a relatively low temperature (400 K), while the displacement-induced defects recovered at a higher temperature (higher than 500 K). According to the comparison between the DLTS analysis and current gain recovery, the accepter-like defects (V-O and V ₂ (−/0)) act an important role in irradiated NPN BJTs.