Radiation induced lifetime degradation in SIMOX structures

A less usual aspect of γ-irradiation (up to 10 Mrad dose) effects is investigated, namely the evolution of carrier lifetime and surface generation velocity. A drain current transient method is adapted and improved in order to evaluate subsequent degradation mechanisms in MOS/SIMOX structures. As a consequence of the biasing conditions during irradiation, most of the damage is found at the front Si-SiO₂ interface and is related to interface state creation. The carrier lifetime decreases whereas the surface generation velocity increases with radiation dose. The transistor geometry is also very important, edge defect formation being responsible for an additional degradation of the effective lifetime