n before the drift term, the current equation becomes simply Jp0 = Po E. The differential equation can be solved in X for 1D problems: Provided that E for tox=10 nm, the "dry" hole density is nearly uniform and we can have an order of magnitude of the steady-state free hole density: Po 7 carriers cm-3 III-23 per rad/s, which could seem very low. However, these carriers must not be neglected. They are not lost as they appear as inputs in the following equations related to the subsequent step where the deep trapping occurs. 3.7. THIRD STEP: TOWARDS PERMANENT TRAPPING OF CHARGE In the vicinity of the semiconductor interface, there exists a disturbed region that is the transition between the crystalline silicon and the amorphous silicon dioxide. Deep hole traps, initially neutral, become converted into positive fixed charge by trapping holes (and eventually relaxing into another configuration state which stabilizes the trapping). The probability of capture for a hole is a function of the density of empty traps, and therefore scales with dose initially, before becoming sublinear and saturating at higher doses. 3.7.1. MODELING THE TRAPPING Before modeling the detrapping, we shall follow the method developed in [Pail-99], which is a complete treatment of models having been proposed these 20 last years by [McGa-80] for low dose regime, and extended to saturation regime in [Lera-89a]. All these models are based on trapping of hole and electron participating to the flux on a given trap profile, according to the proposition of [Kran-87]. Here, the fluxes are defined by drift-diffusion equations. Note that an alternative formulation exists, where the "flux" is defined as the product of the thermal velocity by the carrier density. These two alternatives categorized as the "J-Model" and the "V-Model" will be compared in the section 4.2. We first describe the J-Model which is probably easier to picture out, and which has been much more in use during the last decade. 3.7.2. EQUATIONS RELATIVE TO CARRIERS As mentioned above, duri