Emmanuel Ifeanyi Ugwu

By E. I. Ugwu

Part of the book: Wave Propagation

By Emmanuel Ifeanyi Ugwu

The review of the effect of annealing and doping zinc oxide thin films on both the structural and optical properties has been carried out for different growth techniques such as sol–gel growth technique. The structural and optical properties were carried out using thin films were characterized SEM, XRD while TE and TM guided mode spectra, UV–VIS–NIR (HR4000Ocean Optics) and UV–Visible spectrometry were used accordingly respectively. From the results, it was clearly observed the both the morphological and the crystal characteristics structural characteristic, although increase in the percent of doping element affected it as the diffraction peak was shifts slightly to a lower angle side with report that crystal structure of the film deteriorate at a higher doping concentration of doping element as it decreases the c-lattice. There was also adjustment on the band gap of the material when it was annealed at various temperatures and also when the doping concentration was varied. The film exhibited lower absorbance, high transmittance depend on the regions of electromagnetic wave spectra.

Part of the book: Sol-Gel Method

By Emmanuel Ifeanyi Ugwu

The analysis of the calcium sulphide thin film material which is one of the families of chalcogenide groups of thin film materials was carried out in this work using a theoretical approach for which the propagated wave through the medium of the thin film that is deposited on a glass substrate is considered to be a scalar wave in nature. The thin film material is sectioned into twos, first section is termed homogeneous reference dielectric constant, εref where no thin film is deposited on the substrate and the second part is termed perturbed dielectric function, Δεpz containing the deposited thin film on the glass substrate. These two terms were substituted on the defined scalar wave equation that was subsequently solved using the method of separation of variable which invariably utilized in the transformation of the equation into the second type of Volterra equation. On the other hand, Green’s function approach was also introduced in order to arrive at the model equation that culminates in an expression showcasing the wave propagated through the thin film material medium. This was subsequently applied in the computation of waves, ψz that is propagating through the material medium for various wavelengths within the ultraviolet, visible, and near-infrared region of the electromagnetic wave spectrum for which the influence of the aforementioned dielectric constant and function were invoked. The computed values from this mechanism were in turn utilized in the analysis of the band gap, optical, and solid-state properties of the calcium sulphide (CaS) thin film materials.

Part of the book: Thin Films

By Emmanuel Ifeanyi Ugwu, Adeyeba Adewale Oluwatobi, Rafiu Adewale Busari, Sunday Ikpughul Lyua, Ibrahim Abdullahi Danasabe, Mohamend Jaafar and Usman Rilwan

The study of the influence varied concentrations of ligand and annealing of chemically bath deposited PbS thin film has been carried out the influence of ligand on the optical, solid state, morphological and Electrical properties of the deposited thin films has been investigated. The absorbance, transmittance from the UV-VIS spectrophotometer and other parameters such as absorption coefficient, reflectance, energy band gap, optical conductivity indicate that there is a effect of ligand variation on the properties and the absorption coefficient of the films was found to increase as the concentration of ligand as they annealed to the same temperature and in all case they decreases towards longer wavelength region and the energy band gap was observed to increase from 1.61 to 3.71 eV as the concentration of ligand increases. The surface morphology of the SEM micrographs result shows that the deposited thin films are of polycrystalline and the particle grains are evenly distributed across the substrate’s surface indicates that the grain sizes of the films are dependent on the molar concentration of ligand increases while the XRD showed where the preferential plane with highest diffraction intensity is located.

Part of the book: Structural and Chemical Features of Chalcogenides