The preparation of thin films of some oxides by the pyrolysis method

It is shown that the pyrolysis method is quite an attractive technique for the preparation of oxide films of many metals with predetermined properties in a wide range of compositions. The use of oxygen in the pyrolysis process has made it possible to obtain filmsmore perfect in structure (oriented and single-crystal). Some experimental data on the preparation of semi-conductor and dielectric oxide films (ZnO, In2O3, Al2O3) by pyrolysis of corresponding metal-containing organic compounds (Zn propionate, In acetylacetonate, Al ethylate) are described. A relationship was established between the structure of the films and the conditions of their formation. In the process it was revealed that the nature of the substrate and its temperature were the determining factors. Electron diffraction analysis showed that the structure of the In2O3 films changed from an amorphous to a well oriented one and this corresponded with a change of resistivity from 1012 to 102 ohm cm. It was possible to obtain ZnO single-crystal films on mica with a resistivity of 108 ohm cm. Films with different resistivities (107–1012 ohm cm) were obtained by the decomposition of previously co-deposited aluminium and chromium acetylacetonates. The difference in resistivity was shown to depend on the Cr2O3 content of the deposited films. The high dielectric strength of Al2O3 polycrystalline films (thickness 3–5μ) made it possible to use them as insulating coatings for radio valve heaters.