Journal of Optoelectronics and Advanced Materials 

About: Journal of Optoelectronics and Advanced Materials is an academic journal. The journal publishes majorly in the area(s): Thin film & Amorphous solid. It has an ISSN identifier of 1454-4164. Over the lifetime, 2925 publications have been published receiving 18103 citations.

Preparation and characterization of ZnO thin films deposited by sol-gel spin coating method

Abstract: ZnO thin films have been deposited onto the glass substrates by the sol-gel spin coating method at different chuck rotation rates. This method was used for the preparation of thin films of the important semiconductors II-VI. The effect of deposition parameters on the structural, optical and electrical properties of the ZnO thin films was investigated. Zinc acetate dehydrate, 2-methoxethanol and monoethanolamine (MEA) were used as a starting material, solvent and stabilizer, respectively. Thermogravimetric analysis (TGA) of the dried gel showed that weight loss continued until 300 o C. The crystal structure and orientation of the ZnO thin films were investigated by X-ray diffraction (XRD) patterns. The grain size of the films was calculated using the Scherrer formula. The optical absorbance and transmittance measurements were recorded by using a double beam spectrophotometer with an integrating sphere in the wavelength range 190-900 nm. The optical absorption studies reveal that the transition is direct band gap energy. The optical band gaps and Urbach energies of the thin films were determined. The I-V plots of the ZnO thin films were carried out in dark and under UV-illumination. The obtained ZnO thin films can be used as a photovoltaic material.

Photodynamic therapy in oncology

Abstract: One of the greatest problems of the medical world is cancer, the second most important cause of death on Earth. During the last decade an increase of malignant tumors was seen in Romania, cancer being, after the cardiovascular diseases, the most frequent cause of mortality. The powerful impact of cancer on human life is obvious not only in the death rate but in the number of new cases and living diseased. Therefore, early diagnosis and treatment of cancer has become one of the priorities of the medical world. Current ways of treating cancer (surgery, radiotherapy, chemotherapy) are sometimes only palliatives, that’s why research for new methods to cure cancer is a continuous struggle around the world. Such research have lead to new ways of dealing with this disease based on the induced photochemical effect of light radiation on tumors, known as photochemotherapy or photodynamic therapy. Photodynamic therapy is a method of local treatment of the tumor by administrating a photosensitizing substance which is selectively absorbed by the tumor cells and which, during the irradiation with optical radiations, ends in destroying the tumoral tissue. Although in experimental phase, the obtained results of phototherapy in the latest period are remarkable and have lead to growing interest to this method. The application of photodynamic therapy in current practice raises some problems: the type of potosensitizer (the way of administration, how to prepare it, therapeutic concentration), the radiation source (type, irradiation parameters: wavelength, energy, exposure time, pulse duration, pulse frequency, etc), methods of determining the biologic response, etc. Until now, there are numerous studies on each of these matters. A synthesis of these studies is the subject of this article.

A new version of the RMC++ Reverse Monte Carlo programme, aimed at investigating the structure of covalent glasses

Abstract: A new version of the RMC++ Reverse Monte Carlo (RMC) software, with major modifications and additions, is introduced. The capabilities of the code are demonstrated on the example of Si 40 As 25 Te 35 chalcogenide glass, for which simultaneous modelling of neutron and X-ray diffraction, as well as of (two sets of) EXAFS data is presented. By the extensive use of coordination constraints partial radial distribution functions (prdf) could successfully be separated.

Nonlinear properties of chalcogenide glass fibers

Abstract: Chalcogenide glasses have demonstrated high third-order Kerr (Χ (3) ) nonlinearities up to 1000x higher than silica glass which make them attractive for applications such as nonlinear switching, optical regeneration, Raman amplification, parametric amplification, and supercontinuum generation. Poling of chalcogenide glasses to induce an effective second order (Χ (2) ) nonlinearity has also been demonstrated and opens the possibility for the use of poled glass waveguides for applications such as frequency conversion or electro-optic modulation. Stimulated Brillouin scattering (SBS) has also been investigated in As 2 S 3 and As 2 Se 3 single-mode fibers. The threshold intensity for the stimulated Brillouin scattering process was measured and used to estimate the Brillouin gain coefficient. Preliminary results indicate record high values for the figure of merit and theoretical gain, compared to silica, which bodes well for slow-light based applications in chalcogenide fibers.

Structural and optical properties of zinc oxide thin films prepared by spray pyrolysis method

Abstract: Polycrystalline ZnO thin films were deposited on a glass substrate by a spray pyrolysis technique using solution of zinc acetate and air as the carrier gas at 400 °C temperature. Optical constants such as refractive index n and extinction coefficient k, were determined from transmittance spectrum in the ultraviolet-visible-near infrared (UV-VIS-NIR) regions using envelope methods. The films were found to exhibit high transmittance (>90 %), low absorbance and low reflectance in the visible regions. Absorption coefficient a, and the thickness of the film t were calculated from interference of transmittance spectra. The energy band gap, and the thickness of the films were evaluated as 3.27 eV and 0.31-0.52 pm respectively. The crystallographic structure of these films was analyzed with x-ray diffractometer. The films were polycrystalline in nature with preferred (002) orientation perpendicular to substrate surface and the grain size estimated to be 40 nm. The extended x-ray absorption fine structure (EXAFS) calculations above the K-edge of Zn in the ZnO thin film have been performed by using real-space multiple scattering of photoelectrons. For ZnO thin films, the values of the correlated mean square relative displacements of nearest-neighbor atoms derived from EXAFS spectra show good agreement with those measured from the x-ray diffraction experiments.