Trapping Effects in Irradiated and Avalanche-Injected MOS Capacitors

Avalanche-injection of holes and electrons into nonirradiated and irradiated MOS capacitors, respectively, were used to study hole traps in the SiO2. The trapping parameters for holes, and for electrons in the presence of trapped holes, were obtained in the range 10-14 - 10-13 cm2 for oxide thicknesses in the range 200 - 1000Å. A dominant bulk specie is determined to tail off from the Si/SiO2 interface with a characteristic distance of 150-200Å for dry oxide and approximately 400Å for wet oxide. The electron-injection is shown to be an effective probe of the trapped-hole distribution in the SiO2 after irradiation. The effect of electron compensation of trapped holes during irradiation had been included in the trapping kinetics. C-V shifts and interface state build-up near mid- band after irradiation were found, from irradiation experiments, to follow the same linear dependence on the integrated electron and hole flux crossing the Si/SiO2 interface.