Synergistic Effect of Ionization and Displacement Defects in NPN Transistors Induced by 40-MeV Si Ion Irradiation With Low Fluence

Based on 3DG110 transistors and special gated NPN (GNPN) transistors, the characteristic of the synergistic effect between ionization and displacement defects induced by 40-MeV silicon (Si) ions with low fluence was investigated in terms of deep-level transient spectroscopy (DLTS). Nonlinear relationship, produced by the synergistic effect, between low fluence and radiation response can be obviously observed in the bipolar junction transistors (BJTs) under the exposure of 40-MeV Si ions. The DLTS signals of displacement defect centers and oxide-trapped charges are detected in the base-collector junction of the 3DG110 transistors. Meanwhile, based on the GNPN transistors, the DLTS signals of interface traps and displacement defects are measured in the base-collector junction. By comparison of the change in electrical parameters and the DLTS signals, it is found that the interface traps induce an enhanced effect to displacement defects in the base-collector junction of NPN BJT, whereas the oxide-trapped charge can suppress the DLTS signals of deep-level centers to a certain extent. Compared with the suppression action, the enhanced effect rising from ionization damage gives more contribution to the displacement damage. Moreover, the bias used during DLTS measurements can influence the characteristics of DLTS signals caused by oxide-trapped charge and interface traps. With increasing bias, both the height and temperature of ionization defect peaks in the DLTS spectra will increase, illustrating that concentration and energy level of these defects are raised.