  We experimentally investigated total ionizing dose (TID) response of the
input-stage PNP transitor in an operational amplifier LM324N with various
initial displacement damage (IDD). We found that, the damage first decreases
and then increases with the total dose, which can be exactly described by a
dose-rate-dependent linear generation term, an IDD-dependent linear annealing
term, and a dose-rate-dependent exponential annealing term. We demonstrate
that, the first two terms are the well-known TID and injection annealing
effect, respectively, while the third term stems from the reactions between the
TID-induced protons diffusing from silica and the defects generated in silicon,
which implies the presence of a unexplored proton-defect interaction between
TID and DD effects. Moreover, we find that such an interaction is as strong as
the injection annealing. Our work show that, beside the well-known Coulomb
interaction of trapping charge in silica with carriers in silicon, a strong
proton-defect interaction also plays important role in the synergistic damage.
