Physical properties of zinc oxide films deposited by dual-ion-beam sputtering are analyzed to point out the performance of this technique for the deposition of this material. The films are deposited by sputtering a zinc oxide target with an argon-ion beam, while a second low-energy beam, the assistance ion beam, impinges directly on the growing films. Results are presented for ZnO films deposited at room temperature with different oxygen/argon ratios in assistance ion beam and different sputtering ion-beam currents. Elemental, structural, and electrical analyses have been performed on films. All the films show the typical crystallographic orientation, with the c axis perpendicular to the substrate. The oxygen percentage in the assistance ion beam plays an important role in controlling the electrical resistivity of the films.

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An alternating copolymer, poly(2,5-dioctyloxy-1,4-phenylene-alt-2,5-thienylene), has been synthesized and used in this research. The behavior of the floating film at the air-water interface has been investigated by measuring surface pressure versus area Langmuir isotherms and contemporaneously by reflection spectroscopy and Brewster angle microscopy. The floating films were transferred by the Langmuir-Schäfer (horizontal lifting) method onto various substrates. It is apparent from these analyses that the effective conjugation length is larger than those in other electroactive polymers and that a strong coplanarity and interchain association takes place above all in the floating film on the water surface and in the transferred multilayers. Such films were used as the active layers in resistive chemical gas sensor devices, thus revealing excellent sensitivity toward NO(2), reversibility, and time stability of the response.

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