Annealing effects and DLTS study on NPN silicon bipolar junction transistors irradiated by heavy ions

摘要

Isochronal anneal sequences have been carried out on 3DG112 silicon NPN bipolar junction transistors (BJTs) irradiated with 20 MeV bromine (Br) heavy ions. The Gummel curve is utilized to characterize the annealing behavior of defects in both the emitter-base depletion region and the neutral base. We find that the base current (I_B) decreases with the increasing annealing temperature, while the collector current (I_C) remains invariable. The current gain varies slightly, when the annealing temperature (T_A) is lower than 400 K, while varies rapidly at T_A ＜ 450 K, and the current gain of the 3DG112 BJT annealing at 700 K almost restore to that of the pre-radiation transistor. Deep level transient spectroscopy (DLTS) data is used to assign the relative magnitude of each of the important defects. Based on the in situ electrical measurement and DLTS spectra, it is clear that the V_2(-/O)+V-P traps are the main contribution to the degradation of current gain after the 20 MeV Br ions irradiation. The V_2( - /O)+V-P peak has many of the characteristics expected for the current gain degradation.