MICROSTRUCTURE OF IRIDIUM ENRICHED PtxIr(1–x) FILMS PREPARED BY CHEMICAL VAPOR DEPOSITION

Abstract

MOCVD processes for the fabrication of PtxIr(1–x) films (x < 0.3, thickness 1.5-1.8 µm) on the contacts of diagnostic electrodes and titanium discs are developed using a combination of Pt(II) and Ir(I) acetylacetonate (acac) derivatives (Pt(acac)2, Ir(cod)(acac) (cod = cyclooctadiene-1,5) and oxygen as a gas reagent. It is shown that the ratios of metals in the films prepared on different types of supports are similar within the same experiment. The films contain phases of solid solution PtxIr(1–x) without admixtures of metallic and oxide phases; the ratio of metals in the sample volume corresponds to the one experimentally specified. EDS and XPS methods determine a lower iridium content after the formation of PtxIr(1–x) films in the subsurface layers (10 nm) than the XRD method. The surface of PtxIr(1–x) films consists of agglomerates formed by small particles. When the Pt content decreases from x = 0.3 to x = 0.2, the average size of these particles decreases from 29 nm to 24–25 nm and then remains virtually constant. The capacitance values of contacts with PtxIr(1–x) films vary within 62.6-84.5 mC/cm2.