Al doped ZnO (AZO) films are fabricated by using sol-gel spin coating method and changes in electrical, optical and structural properties due to variation in film thickness is studied. AZO films provide c-axis orientation along the (002) plane and peak sharpness increased with film thickness is evident from XRD analysis. Conductivity (σ) of AZO films has increased from 2.34 (Siemens/cm) to 20156.27 (Siemens/cm) whereas sheet resistance (R_sh) decreases from 606300 (ohms/sq.) to 2.08 (ohm/sq.) with increase of film thickness from 296 nm to 1030 nm. Optical transmittance (T%) of AZO films is decreased from around 82% to 62% in the visible region. And grain size (D) of AZO thin films has been found to increase from 19.59 nm to 25.25 nm with increase of film thickness. Figure of Merit is also calculated for prepared sample of AZO. Among these four sample of AZO thin films, L-15 sample (having thickness in 895 nm) has provided highest figure of merit which is 5.49*10^^-4 (_Ω^-1).

The optoelectronic properties of Sn-doped ZnO nanoparticles.

The ZnS thin films have been deposited by radio frequency magnetron sputtering at room temperature. Post-deposition rapid thermal annealing treatment was done for the films deposited at different powers ranging from 70 to 100 W. One peak is observed for as-deposited and annealed thin films at around 28.48° corresponding to the (111) reflection plane indicating a zincblende structure. The overall intensity of the peaks and the FWHM values of as-deposited films increased after annealing corresponding to the increase in crystallinity. The optical energy bandgap is found in the range of 3.24–3.32 eV. With increasing annealing temperature, the decrease in the Urbach energy values indicating a decrease in localized states which is in good agreement with the XRD results where the crystallinity increased. The surface morphology of the films seems to be composed of Nano-granules with a compact arrangement. Apparently, the grain size increases in the deposited films as annealing temperature increases. The compositional ratio attained close to the stoichiometric ratio of 1:1 after annealing. From the Hall effect measurement, the carrier concentration and mobility are found to increase after annealing. The high carrier concentration and mobility also comply with structural and optical analysis. Best results are found for the film annealed at 400 °C deposited at 90 W.

Nano-crystalline CdSe thin films of different thicknesses under sub-micron range were deposited on glass substrate via thermal evaporation route. A gradual deterioration in film crystallinity confirmed by XRD line profile analysis has been accompanied by a reduction in Cd to Se molar ratio as the film thickness decreases. A coordinated microstructural and crystallographic orientation distribution analysis explicitly demonstrated that CdSe tends to grow in nano-sized columns with hexagonal c-axis parallel to its growth direction on glass substrate. A thickness dependence of structural evolution was discussed in terms of aspect ratio of the columnar structure and dispersion in orientation of hexagonal (002) basal plane. The variation in the spectra of optical constants [n(λ), k(λ)] obtained from Swanepoel envelop method was interpreted in terms of crystallographic defects arising from stoichiometric disorder which was also accounted for the observed thickness dependent shifts in band gap and valence band split energy. The bathochromic shifts in dielectric and energy loss functions, optical conductivity, skin depth and cut-off energy were discussed in detail along with the variations in their spectral shapes in connection with the dispersion in the real and imaginary parts of complex refractive index, which might shed a new light upon holistic comprehension of thickness dependent optical properties of other chalcogenide semiconducting thin films.

A potential solar absorber material, sputtered kesterite Cu₂ZnSnS₄ (CZTS) thin film, has been extensively studied in recent years due to its advantageous properties, including the earth abundance of its constituent elements, nontoxicity, suitable band gap, and high absorption coefficient. 2000 nm CZTS thin films were deposited on soda lime glass by a sputtering technique. The prepared films underwent a postannealing treatment for crystallization in which different temperatures and pressures were applied to understand its impact on film growth, phase formation, and stoichiometry. The annealed samples were subsequently characterized by Raman and UV-visible (UV-Vis) spectroscopy, energy-dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The thickness of each film was measured using a surface profilometer and from a cross-sectional image obtained by SEM. The XRD pattern for each film showed characteristic (112), (220), and (312) peaks, and the phase purity was confirmed via Raman studies. Film surface morphology and roughness were studied by AFM. The root mean square roughness was found to increase with annealing temperature and base pressure. The chemical compositions of the prepared samples were analyzed by EDX, and the films showed desired stoichiometry. UV-Vis absorption spectroscopy indicated that the direct band gap energies (E_g) of the films were 1.47 eV–1.51 eV, within the optimum range for use in solar cells. These attractive properties of the sputtered CZTS thin film should heighten interest in its use as a solar absorber layer in the next-generation photovoltaic cells, suggesting that it possesses substantial commercial promise.

This study explored the structural, electrical, and magnetic properties of diamagnetic aluminium (Al³⁺) substituted nickel–zinc–cobalt (Ni–Zn–Co) mixed spinel ferrites, though the research on this area is in the infancy stage.