Research on interaction between displacement defects and oxide charge in NPN transistors based on deep level transient spectroscopy

Based on 70 keV, 170 keV protons and 5 MeV protons, the interaction between oxide charge and displacement defects in 3DG112 NPN bipolarjunction transistors (BJTs) was investigated. Both ionization and displacement damage can result in the current gain degradation of BJTs. The degradation of the transistor varies linearly with increasing the irradiation fluence for 170 keV and 5MeV protons but nonlinearly for 70 keV protons, implying that the 170 keV and 5 MeV protons mainly induce displacement damage to the NPN BJTs, while the 70 keV protons cause non-bulk damage. Based on the calculation, the end of the range for 5 MeV protons is much deeper than the base and DLTS probed region. 70 keV protons can only arrive at oxide layer, and 170 keV protons exhibits a maximum displacement damage in the base region. The displacement defects in based-collector junction of 3DG112 transistor induced by 5 MeV proton exposures, and the oxide trapped charge caused by 170 keV and 70 keV proton irradiations, were discovered by DLTS technology.