 case of thick oxide, because the internal electric field developed by the charge itself is comparable to the field applied from the gate voltage and produces large distortions of the trapped charge profile, as remarked by [Boes-76]. We therefore show the unique help of a simple 1-D code, allowing investigations of the complex relation between trap profile (TP), internal potential build-up (PB), field-collapse (FC) and field-enhancement (FE). The knowledge of oxide parameters in space and energy is mandatory to fully predict charge trapping in any situation of time-dependent voltage profile. We show this process can be applied to various real-life situations such as MOS, CMOS, POWER-MOS, Field-Oxide parasitic transistors, and even LOCOS and Trench lateral transistors with some simplifying assumptions. 4.2. SIMPLIFIED NUMERICAL 1D ON LAPTOP COMPUTER: THE TRAPPOX V.4 CODE AND VARIOUS APPLICATIONS In this simplified code, we take only the trapping of holes into account. where Cp and Rpn stand for hole capture and trapped hole recombination with free electrons. The continuity equations for electrons and holes gives the "drivers" n and p for this trapped charge: III-48 where jn and jp observe the drift-diffusion equation. The generation factor that creates an equal density of electrons and holes n and p is in turn written as follows: (81) G=go Y(E)D where D' is the time derivative of the dose versus time, go = rad(SiO2)1.cm and Y(E) the generation yield of electron-hole pairs escaping the initial recombination: (m=0.9 and Ec=1.35 MV/cm for 10 keV X-rays and m=0.9 and Ec=0.55 MV/cm for Co 1.17- 1.33 MeV -rays). Evidently, it is of most importance in medium-to-thick oxides operating at relatively low applied voltage to take into account the internal field modulation by the charge density through Poisson equation. This makes the analytical scheme really tricky and makes the whole problem really self-consistent. Although analytical solutions have been developed in limiting cases [see chapters above], they fail to describe