STRUCTURAL, OPTICAL, AND ELECTRONIC-PROPERTIES OF MAGNETRON-SPUTTEREDPLATINUM OXIDE-FILMS

Stable platinum oxide films have been prepared through magnetron sputt ering and have been analyzed on the bases of energy-sensitive microana lyses, x-ray diffraction, resistivity, and optical reflectance measure ments. The complex dielectric function has been determined for various oxygen contents in the film covering the wave-number regime 50 cm(-1) -lambda(-1)-50 000 cm(-1). The vibrational properties are dominated th rough a strong band, centered at 765 cm(-1), associated with a asymmet ric stretching mode of the Pt-O bond. The films are amorphous, with ch emical composition PtOx, where 1<x<2.1, and are considered as a homoge neous solid solution of PtO and PtO2. The materials system displays a conductor-insulator transition at x greater than or equal to 2, in con nection with an optical band gap E(g) of similar to 1.2 eV in the full y oxidized state. The conduction mechanism over the whole range of com positions is thermally activated and is determined through a large den sity of localized states extending into the band gap. At x<2 the optic al gap disappears, consistent with the semimetallic behavior of the ma terials system for this range of composition. (C) 1996 American Instit ute of Physics.