This work aims to determine the characteristic I(breakdown voltage) of the inverse current in a GaAs PN junction diode, subject to a reverse polarization, while specifying the parameters that influence the breakdown voltage of the diode. In this work, we simulated the behavior of the ionization phenomenon by impact breakdown by avalanche of the PN junctions, subject to an inverse polarization.We will take into account both the trapping model in a stationary regime in the PCN structure using like material of basis the III–V compounds and mainly the GaAs semi-insulating in which the deep centers have in important densities. We are talking about the model of trapping in the space charge region(SCR) and that is the trap density donor and acceptor states.The carrier crossing the space charge region(SCR) of W thickness creates N electron–hole pairs: for every created pair, the electron and the hole are swept quickly by the electric field, each in an opposite direction, which comes back, according to an already accepted reasoning, to the crossing of the space charge region(SCR) by an electron or a hole. So the even N pair created by the initial particle provoke N2 ionizations and so forth.The study of the physical and electrical behaviour of semiconductors is based on the influence of the presence of deep centers on the characteristic I.V / current-tension, which requires the calculation of the electrostatic potential,the electric field, the integral of ionization, the density of the states traps, the diffusion current of minority in the regions(1) and(3), the current thermal generation in the region(2), the leakage current in the surface, and the breakdown voltage. This work aims to determine the characteristic I (breakdown voltage) of the inverse current in a GaAs PN junction diode, subject to a reverse polarization, while specifying the parameters that influence that breakdown voltage of the diode. In this work, we simulated the behavior of the ionization phenomenon by impact breakdown by avalanche of the PN junctions, subject to an inverse polarization. We will take into account both the trapping model in a stationary regime in the PCN structure using like material of the the III-V compounds and mainly the GaAs semi-insulating in which the deep centers have in important densities. We are talking about the model of trapping in the space charge region (SCR) and that is the trap density donor and acceptor states. of W thickness creates N electron-hole pairs: for every created pair, the electron and the hole are swept quickly by the electric field, each in an opposite direction, which comes back, according to an already accepted reasoning, to the crossing of the space charge region (SCR) by an electron or a hole. So the even N pair created by the initial particle provoke N2 ionizations and so forth. The study of the physical and electrical behavior of semiconductors is based on the influence of the presence of deep centers on the characteristic IV / current-tension, which requires the calculation of the electrostatic potential, the electric field, the integral of ionization, the density of the states traps, the diffusion current of minority in the regions (1) and (3), the current thermal generation in the region (2), the leakage current in the surface, and the breakdown voltage.