The structure, morphology, and mechanical properties of sol-gel zirconia films have been examined using XRD, AES depth profiling, AFM, and ultramicro indentation. There is a systematic variation in the structure and morphology of the zirconia films with increasing thickness. These changes include increases in the amount of monoclinic phase, substrate oxides, and a decrease in grain size. Ultramicro indentation measurements indicate measured hardness increases with film thickness. The highest hardness value was 6.12 GPa for a 900 nm thick film. However, these values may be influenced by the substrate oxide layer at the film/substrate interface which increases with film thickness. The modulus of the films appears to be thickness independent. As the films are made up of a number of separately fired layers, it appears that the property changes observed are also related to the number of thermal cycles experienced by the sample.
We present a comparative study of GaN grown on quartz and on sapphire by laser assisted metalorganic chemical vapour deposition. Films were characterised by X-ray diffraction, Raman spectroscopy and optical transmission. Films grown on both substrates are polycrystalline, with the dominant orientation of (0002) wurtzite or (111) cubic for growth temperatures 550°C and lower. In films grown at 625°C, both on quartz and on sapphire the crystallites show a variety of orientations, all attributed exclusively to wurtzite phase. Films grown at the same temperature are characterised by similar value of the Urbach parameter for both substrates. The Raman spectra in all examined films are alike, and characteristic for a disordered cubic GaN.
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