Softening and stiffening of phonons in rutile titanium dioxide films are investigated by in situ micro-Raman studies during energetic ion irradiation. The in situ study minimized other possible mechanisms of phonon dynamics. Initial softening and broadening of Raman shift are attributed to the phonon confinement by structural defects and loss of stoichiometry. The stiffening of A 1g mode is ascribed to large distortion of TiO 6 octahedra under the influence of lattice strain in the (110) plane, which gives rise to lengthening of equatorial Ti-O bond and shortening of apical Ti-O bond. The shortening of apical Ti-O bond induces stiffening of A 1g mode in the framework of the bond-order-length-strength correlation mechanism. V C 2014 AIP Publishing LLC.

ZnO thin films were deposited using atom beam sputtering and their modifications have been shown by two processes: (a) thermal annealing of ZnO thin films in oxygen and (b) athermal annealing by irradiation of these films by swift heavy ions (SHIs) in a high vacuum chamber. The as-deposited films showed the nanocrystalline nature with a preferred orientation along the c-axis of the hexagonal structure as revealed by x-ray diffraction (XRD) and Raman spectra. The influence of the thermal annealing and athermal annealing on the structural and surface modifications of these thin films were investigated. XRD and Raman spectroscopy confirmed the improvement in the crystallinity of ZnO thin film by both thermal annealing and SHI irradiation. The Zn–O bonding was confirmed by Fourier transform infrared spectroscopy and the interpretation of IR spectra corroborated the XRD and Raman results. Surface morphology was investigated by atomic force microscopy. The AFM study of the films implied no significant change in the roughness of the films in both types of annealing conditions. It was concluded that the modification of nanocrystalline ZnO thin film could be possible by both thermal and athermal annealing. Results indicate that transient annealing by SHI irradiation induces the highly textured c-axis oriented ZnO thin film for device applications, comparable to those of high temperature annealing.

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The topography evolution using the high energy heavy ion irradiation revealed the fact that ion bombardment produces self-affine nanostructures, creating peculiar surface morphologies and regular structures on the surface of the ZnO thin film at certain fluences. The self-affine nanopatterns produced on the surface of ZnO thin film under swift heavy ion irradiation are different types of nanostructures such as nanodimensional grains aligned like a linear array. Scanning probe microscopy is used for investigating the ZnO surfaces and UV-visible spectroscopy for studying the effect of surface modification on optical properties. The two-dimensional power spectral density of the irradiated ZnO thin films have been evaluated for each image to extract the value of growth factor (β) and roughness exponent (α). The exponent n increases from 2.2 to 4.0 up to a critical value of fluence and beyond which it decreases. These values suggest that ion assisted∕induced diffusion process plays a crucial role in the evolution of self-affine nanostructures on ZnO surface.

The present study reports the structural, morphological, optical and magnetic properties of N ion implanted CeO2 thin films deposited by a RF magnetron sputtering technique.