 actual cases on the whole gate voltage and dose range. This is the scope of this modeling to bring new insights on this. At this point, it can be remarked that two types of models have been considered these last 20 years, which differ from one another in the C and R terms. We shall categorize them as "V- Model" (deriving from thermal velocity Vth) and "J-Model" (deriving from current flux j). 4.2.1. V-MODEL The equation is simply based on the carrier density at abscissa X. Note the similarity with some limiting cases of the Shockley-Read-Hall equation. (83) and where Vthn and Vthp are the "thermal velocities" of the electrons and holes involved in the trapping and recombination process. 4.2.2. J-MODEL These equations derive from simple ballistic probability of a localized particle participating to fluxes j, to be trapped with a probability expressed by cross sections : (84) C p = (NTp - Pt) = pt jp III-49 4.2.3. TRENDS IN MODELING The V-model seems to have had the favors of early workers (e.g. [Tayl-82], [Hugh-85], [Lera- 89a] p. 173, [Vasu-94]), whereas since the last 10 years, the J-model is used by a strong majority (e.g. [Kran-87], [Lera-89a] p.69, [Krantz-91], [Lee-91], [Flam-92], [Herv-94], [Pail-94], [Pail- 95b], [Esco-95b], [Bris-96], [Mila-98], [Grav-98]). It is nearly evident that the response of the two settings are strongly different with respect to one input, i.e. the hole mobility, and one output, i.e. the V ot shift per unit of dose as the gate bias during irradiation is made varying. The results presented here compare the two sets of equations implemented as options in a single code TRAPPOX v.4. 4.2.4. METHOD USED IN TRAPPOX R v.4 AND CODE IMPLEMENTATION In the case of medium (Power-MOS) or thick (any parasitic MOS structure, spacer (bipolar base), lateral (edge or field oxide of MOS transistors) or buried (SOI)), the (external) weak field developed by boundary electrodes (gates, emitter electrode, supply or signal lines in actual devices) can be easily overcome by the internal field created by t