An explicit study of comparison on the basis of structure and electronic properties of ZnO nanostructures was discussed. ZnO synthesized by sol-gel and hydrothermal method without using any surfactant leads to the formation of two different morphologies. Rietveld crystal structure refinement of X-ray diffraction patterns confirmed the wurtzite structure of both samples. Raman spectra also confirmed the wurtzite phase formation and improved crystallinity in sample synthesized by hydrothermal route that are concurrent with results obtained from X-ray diffraction. Field-emission scanning electron microscopy revealed the formation of ZnO spherical nanoparticle structure for sol-gel method and flower like μ-structure for ZnO prepared through hydrothermal route. Williamson-Hall equations applied to study the strain and stress parameters present in the material, show the decrease in their values as the crystal size increases. Energy band gap is calculated using diffused reflectance spectroscopy. Near-edge X-ray absorption fine-structure measurements at O K- and Zn L3,2- edges simulated with FEFF9.05 code confirmed the presence of oxygen vacancies. Further extended x-ray absorption fine-structure revealed a similar local atomic structure for both samples despite having different morphologies.

Cu doping in ZnO modifies the electronic structure and the hybridization between Cu and O orbitals results in RTFM due to formation of BMPs.

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This paper reports on the laser induced changes on the optical properties of a-Ga50Se50 thin films prepared by the thermal evaporation technique under vacuum. Thin film samples, on a glass substrate, were exposed to laser light of wavelength λ = 532 nm for different exposure times, tE (tE = 0, 500, 1500 and 3000 s). Optical parameters such as refractive index, absorption coefficient, optical gap, extinction coefficient, real and imaginary dielectric constants, dielectric loss, optical conductivity of as-deposited thin film and their laser induced changes were studied at three different times of exposure. The mechanism of optical absorption follows the rule of the indirect allowed transition model proposed by Tauc and the optical band gap is calculated by Tauc's extrapolation. It is seen that after laser irradiation there is a shift of the optical absorption edge to larger photon energy. The value of the absorption coefficient of the GaSe thin film decreases on exposing the film to laser irradiation. A microscopic model in which heteropolar bonds are broken by absorption of high energy photons and new homopolar bonds are formed simultaneously has been used to describe the effect.