ecessity of recombination to observe charge collapse (C.C.) as a consequence of Field Collapse. For this comparison, we use an oxide of 450 nm biased at +5 Volts (representing a Field-Oxide), featuring a uniform density of traps of NTp=4.41016 cm -3 (10 12 cm-2 with pt pr=10-12 cm -2 Field collapse in TRAPPOXR and code A operating in the V-Model Two cases are run: one with the recombination of trapped holes by electron flux and the other without ( pr=0). III-55 Electric Field (V/cm) Figure 36. Field collapse with TRAPPOXR in the V- Model (with e-h recombination). oxide thickness (A) Dose (krad(SiO2) In figure 36 (above), the 3D representation allows to picture the electric field (z-axis) at any point of the oxide depth (left axis, from gate to silicon). Just at the beginning of irradiation, the gate potential is switched from 0 to +5V and the field is constant across the oxide. Then trapping begins to occur and the field enhances in the silicon region, while it decreases at the gate. At 30 kilorads, the gate field drops to zero, but contrarily to the oversimplified analytical model, charge does not collapse in a sufficient area to allow the field to stay at zero. On the contrary, field enhanced again, going into negative values. At that point, field at the silicon side enhances to greater values (Field Enhancement), allowing the integral of field over oxide to remain at +5 V. The following simulation (fig. Oxide 0.45um, Trap density (6 Time=200s.va -5v[0 200s] Rate=1e3 hXsec 37) shows another simulation hTrappedcharge different 6e+16 representation (code A) based on the same parameters, but using the V-model. 4e+16 It can be clearly seen that Field and Charge Collapse exist in the OkRad OkRad two cases independently of the code structure. 2e+16 Figure 37. Charge collapse with code A in the V-model (with e-h recombination pr=10-13 -13 cm²). III-56 Another interesting feature permitted by simulation is the calculation of the trapped charge profile with and without trapped charge recombination with electrons (fig. 3