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Abstract: The structure and morphology of chromium disilicide (CrSi2) nanometric films grown on 〈100〉 silicon substrates both at room temperature (RT) and at 740K by pulsed laser ablation are reported. A pure CrSi2 crystal target was ablated with a KrF excimer laser in vacuum (∼3×10−5 Pa). Morphological and structural properties of the deposited films were investigated using Rutherford backscattering spectrometry (RBS), grazing incidence X-ray diffraction (GID), X-ray reflectivity (XRR), scanning (SEM) and transmission electron microscopy (TEM). From RBS analysis, the films’ thickness resulted of ∼40nm. This value is in agreement with the value obtained from XRR and TEM analysis (∼42 and ∼38nm, respectively). The films’ composition, as inferred from Rutherford Universal Manipulation Program simulation of experimental spectra, is close to stoichiometric CrSi2. GID analysis showed that the film deposited at 740K is composed only by the CrSi2 phase. The RT deposited sample is amorphous, while GID and TEM analyses evidenced that the film deposited at 740K is poorly crystallised. The RT deposited film exhibited a metallic behaviour, while that one deposited at 740K showed a semiconductor behaviour down to 227K. [Copyright &y& Elsevier]

Abstract: The MAPLE technique has been used for the deposition of nanostructured titania (TiO2) nanoparticles thin films to be used for gas sensors applications. An aqueous solution of TiO2 nanoparticles, synthesised by a novel chemical route, was frozen at liquid nitrogen temperature and irradiated with a pulsed ArF excimer laser in a vacuum chamber. A uniform distribution of TiO2 nanoparticles with an average size of about 10nm was deposited on Si and interdigitated Al2O3 substrates as demonstrated by high resolution scanning electron microscopy-field emission gun inspection (SEM-FEG). Energy dispersive X-ray (EDX) analysis revealed the presence of only the titanium and oxygen signals and FTIR (Fourier transform infra-red) revealed the TiO2 characteristic composition and bond. A comparison with a spin coated thin film obtained from the same solution of TiO2 nanoparticles is reported. The sensing properties of the films deposited on interdigitated substrates were investigated, too. [Copyright &y& Elsevier]

Abstract: Indium tin oxide (ITO) and titanium dioxide (TiO2) single layer and double layer ITO/TiO2 films were prepared using reactive pulsed laser ablation deposition (RPLAD) with an ArF excimer laser. The films were deposited on SiO2 substrates heated at 200 and 400°C. ITO and TiO2 films with uniform thicknesses of about 400 and 800nm, respectively, over large areas were prepared. X-ray diffraction (XRD) analysis revealed that the ITO films are formed of highly orientated nanocrystals with an average particle size of 10–15nm. Atomic force microscopy (AFM) observations indicate rough ITO films surfaces with average roughness of 26–30nm. Pores were also observed. TiO2 films deposited on the prepared ITO films result less crystalline. Annealing at 300 and 500°C for three consecutive hours promoted formation of TiO2 anatase phase, with crystal size of ∼6–7nm. From the scanning transmission electron microscope (STEM) images, it can be seen that the TiO2 films deposited onto the prepared ITO films present a relatively high pore sizes with an average pore diameter of ∼40nm and excellent uniformity. In addition, STEM cross-sectional analysis of our films showed a columnar structure but no evidence of voids in the structure. Therefore, films exhibited large surface area, well suited for dye-sensitized solar cells (DSSC) applications. [Copyright &y& Elsevier]

Abstract: We report morphological and optical properties of a colloidal TiO2 nanoparticle film, deposited on a quartz substrate by using the Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique. Atomic Force Microscopy demonstrated that a good uniformity of the deposition can be obtained. The presence of agglomerates with dimensions of about 1μm in size was noticed. Form UV–vis transmission spectra, recorded in the 200–800nm range, the optical constants and the energy gap were determined besides the film thickness. The optical constants resulted in agreement with the values reported in literature for TiO2 nanoparticle thin films. [Copyright &y& Elsevier]