Proton irradiation at 30°K and isochronal annealing of reactively sputtered Ta thin‐film resistors

Tantalum thin‐film resistors reactively sputtered in oxygen and nitrogen simultaneously have been irradiated by 150‐keV protons at 30°K. The observed conductance increase of the films is ascribed to radiation‐produced defect levels within the inter‐island regions of Ta₂O₅ in these discontinuous films. The nonlinearity of the conductance increase with fluence may be accounted for by a nonlinear rate of defect production due to a combination of spontaneous recombination and close‐pair thermal annealing. The number of unstable sites surrounding each defect is found to be equal to or greater than four for crystalline Ta₂O₅. Thermal recovery of the damage proceeds in two main stages: Stage A (34–150°K) possesses some substructure and is attributed to close‐pair or correlated recombination; stage B (150–300°K) is very broad and structureless and is attributed to uncorrelated annihilation of defects at the gap‐island interface. Negative annealing stages (characterized by a conductance increase) indicate a metallic conduction process via connected metallic islands.