Damage Separation in Proton-Irradiated Bipolar Junction Transistors as a Function of Energy

Damage separation analysis was performed for two types of bipolar junction transistors (BJTs) following proton irradiation over the energy range of 1.6–650 MeV. The functional dependence of excess base current on fluence for each device type is consistent with base polarity as it relates to the effect of oxide-trapped charge on surface recombination. For a given fluence, the excess base current decreases with proton energy due to reductions in non-ionizing energy loss (NIEL) and stopping power. Relative damage coefficients, computed from normalized
$\Delta I_{\mathrm {B}}$
versus fluence curves, imply a mix of ionization and displacement damage. The relative amounts of ionization damage and displacement damage as a function of proton energy are consistent with charge yield (CY), stopping power and NIEL. A simple model for the energy dependence of damage contributions, based on CY and the relative amounts of deposited ionizing and non-ionizing energy, is described. The model calculations as a function of proton energy are in good agreement with the relative damage contributions estimated from the damage separation analysis.