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Zinc oxide (ZnO) and Ni-doped zinc oxide (ZnO:Ni) films are prepared by atom beam sputtering with an intent of growing transparent conducting oxide (TCO) material and understanding its physical properties. The crystalline phases of the films are identified by the grazing angle X-ray diffraction (GAXRD) technique. Thicknesses of the films are measured by ellipsometry. Chemical states of the elements present in the films are investigated by X-ray photoelectron spectroscopy (XPS), which indicates the presence of Ni in the ZnO environment in a divalent state. Average transmission across the ZnO:Ni film was determined to be ∼ 83% in the visible region, which is less than that (∼ 90%) of undoped ZnO films. The resistivity measured by van der Pauw technique of the ZnO:Ni film (∼ 9 × 10 −3 Ω cm) is two orders of magnitude smaller as compared to its undoped counterpart (1 Ω cm). For ZnO:Ni film an average carrier concentration of ∼ 1.4 × 10 19 cm −3 was observed by Hall measurements. Two important mechanisms reported in the literature viz. influence of d-d transition bands and electron scattering from crystallites/grains are discussed as the possible causes for the increase in conductivity on Ni doping in ZnO.

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In spite of several articles, the origin of visible luminescence from germanium nanocrystals in SiO 2 matrix is controversial even today. Some authors attribute the luminescence to quantum confinement of charge carriers in these nanocrystals. On the other hand, surface or defect states formed during the growth process, have also been proposed as the source of luminescence in this system. We have addressed this long standing query by simultaneous photoluminescence and Raman measurements on germanium nanocrystals embedded in SiO 2 matrix, grown by two different techniques: (i) low energy ion-implantation and (ii) atom beam sputtering. Along with our own experimental observations, we have summarized relevant information available in the literature and proposed a Hybrid Model to explain the visible photoluminescence from nanocrystalline germanium in SiO 2 matrix.

Thin films of carbon-containing Au nanoparticles (NPs), prepared by the co-sputtering using a neutral Ar atom beam, were irradiated by 120 MeV Ag ions and also annealed, separately, at increasing temperatures in inert atmosphere. The surface plasmon resonance (SPR) band of the nanocomposite film was observed to be blue shifted (similar to 50 nm) in both cases, with increasing fluence and temperature. The structural changes of Au NPs embedded in amorphous carbon matrix were investigated using X-ray diffraction and transmission electron microscopy. A growth of Au NPs was observed with increasing fluence and also with increasing temperature. A percolation of Au NPs was observed at 500 degrees C. A growth of Au NPs with ion irradiation is explained in the framework of a thermal spike model. Raman spectroscopy revealed the ordering of a-C thin films with increasing fluence and temperature, which is ascribed to a change of refractive index and the blue shift of the SPR band