Extraction and Analysis of Gamma Irradiated Si BJT SPICE Model

The Simulation Program with Integrated Circuit Emphasis (SPICE) model parameters of pre and post-irradiated silicon bipolar junction transistor ( Si BJT) were extracted with the use of Altium Designer (AD)/SPICE model wizard. The percentage changes ( Δ% ) between forward and reverse-bias parameters of existing BJT (ZETEX BCW72) SPICE model were estimated and also the degradation Δ% between the experimental data of pre and post-irradiated Si BJT were calculated. Then the new measured results by comparison were imported into AD/SPICE model wizard to extracts forward-bias parameters. The extracted forward-bias parameters were used to generate reverse-bias parameters through Δ% . The final extracted Si BJT SPICE model parameters were implemented in SPICE simulator to obtained forward and reverse Gummel plots. As expected, base current ( I B ) increases, the collector current ( I C ) increases slightly at low bias base-emitter voltage, leading to current gain degradation due to positive charge trapped in the oxide and interface of the BJT device. In addition, the results of the I B in the forward Gummel flows in parallel with base-emitter junction, while the I B in the reverse Gummel flows across the base-collector junction down to the back side collector contact through the collector region. Finally, the compared results of Si BJT forward Gummel simulation and experimental data showed good agreement.