DEFECT STUDIES IN OXYGEN-ION-IRRADIATED SILICON-BASED METAL-INSULATOR-SEMICONDUCTOR STRUCTURES

Damages induced by 69 MeV oxygen ions (fluence: 1.3 X 10(14) ions cm-2 ) in gold-silicon-nitride-silicon metal-insulator-semiconductor (MIS) structures were studied by measuring the pre- and postirradiation junc tion and interface characteristics. Amount of the space-charge produce d at the silicon-silicon-nitride interface was estimated by measuring capacitance-voltage characteristics and the energies of the defects we re measured with the technique of deep-level transient spectroscopy. T wo new defect levels having energies (E(c)-0.34) eV and (E(c)-0.63) eV were found in addition to the defects detected in the unirradiated de vices. The values of the surface recombination velocities, measured wi th a variable-energy electron beam, indicate that the radiation-induce d defect concentration on the surface was negligible; however, about 7 % degradation in the lifetime of minority carriers in the bulk was obs erved. The results indicate that oxygen ions can be used to modify the junction characteristics of MIS structures while keeping the surface characteristics of the structure almost unaltered.