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Chalcogenide glasses (ChGs) semiconductors have several useful properties, especially in their technical applications. The present work explains the compositional dependence of many physical properties of GexBi5S95-x (x = 0, 10, 20, 30, 35 and 45 at. %). Increasing Ge content reduces the fraction of floppy modes, the lone pair electrons, the stoichiometric deviation, and the heat of atomization, while the average coordination number 〈r〉, constraints, density, and molar volume increased, indicating the alloys have moved from floppy to rigid mode. The average overall bond energy, electronegativity difference, band gap energy, and glass transition temperature were estimated by analyzing the bond energies and its distribution based on the bond ordered network model (CONM). It has been found that all these parameters increase with Ge ≤ 30 at. % and decrease with the further increase of Ge content. This behavior can be explained in terms of the network chemical percolation threshold proposed by Tanaka. This threshold represents a topological phase transition from a two-dimensional structure at r˂2.67 to a three-dimensional structure at r≥2.67. The incorporation of Ge into the glassy Bi-S system yields interesting physical properties such as threshold and phase transition, confirming this composition's suitability for optical storage media.

The current work focuses on working a comparison between two solar cells made with the combination, n-TiO2/p-CuO, and n-TiO2/p-Cu2O devices. The structural, optical, and photovoltaic characteristics were detailed. In the optical section, the optical measurements for the TiO2 (120 nm), CuO (200 nm), and Cu2O (200 nm) thin films were illustrated, and then the energy of optical transition was calculated based on the Tauc formula for each layer. The direct optical gap energies of TiO2, CuO, and Cu2O thin films are 3.24, 1.77, and 2.18 eV, respectively. The front contact electrode in both systems is an ITO- coated glass layer, while the back contact electrodes are Pt, Ni, Au, Co, Ag, Cu, Al, and Mo. The effect of various metals as back contact electrodes on the photovoltaic characteristics of fabricated devices was investigated. The optical and structural characteristics showed the superiority of the fabricated device n-TiO2/p-CuO over the fabricated device n-TiO2/p-Cu2O.

The present research article examined how the thickness of Cd2Ge8Se90 thin films affected their structural and optical characteristics. On pre-cleaned glass substrates, the pristine amorphous Cd2Ge8Se90 thin films of varying thicknesses (d=374, 516, and 816 nm) were synthesized.Swanepoel's strategy was employed to explore the optical characteristics in terms of film thickness, such as the band gap energy (Tauc’s energy) and band tail energy (Urbach’s energy). Also, optical constants, including the refractive index, n, and extinction coefficient (absorption index, k), depend on transmittance spectroscopy.An indirect optical transition mechanism is observable, according to the assessment of the absorption spectra of the thin films under study.As layer thickness increased, the optical band gap shrank, but the tail energy showed a different pattern of this behavior.The refractive index dispersion was characterized using the Wemple-DiDomenico single oscillator concept, and the dispersion parameters were derived.Oscillator and dispersion energies rise as a film's thickness does. Other dielectric parameters including the high-frequency constant, the ratio of free charge carrier concentration to effective mass, plasma frequency, and single oscillator strength are all significantly influenced by thickness.

The structure and kinetics of the crystallization reaction of amorphous \(Cd_{10} Se_{90}\) were studied at different heating rates (5–30 K/min) under non-isothermal conditionsby X-ray powder diffraction, scanning electron microscopy (SEM) and differential thermal analysis (DTA) techniques. The Johnson–Mehl–Avrami(JMA) and isoconversional models were used to describe the DTA crystallization data.A strong heating rate dependence of the activation energy was observed when the data were analyzed using Matusita method. This variation of the activation energy was confirmed by the application of the isoconversional methods of Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), Tang, Starink, and Friedman. These methods showed that the activation energy of crystallization is not constant but varies with the degree of conversion and hence with temperature. This variation indicates that the transformation from amorphous to crystalline phase is a complex process involving different mechanisms of nucleation and growth.

Optical constants of vacuum evaporated thin films in the Se90−xTe10Snx (x = 0, 2.5, 5 and 7.5 at %) system were calculated from reflectance and transmittance data in the wavelength range of 300–2500 nm using Murmann’s equations. The maximum value of refractive index increased and suffered a shift towards the short wavelength as the Sn content increases this behavior can be attributed to increasing the values of cross-linking chains density and decrease tailing. The variations in the real and the imaginary parts of the dielectric constant, the dissipation factor tan(δ), the optical conductivity, the volume, and surface energy loss functions with photon energy have also been reported. The normal dispersion of the refractive index is discussed regarding the single oscillator Wemple-DiDomenico model from which the dispersion parameters were determined. The single oscillator energy, the dispersion energy, the high-frequency dielectric constant, the ratio of free charge carrier concentration to the effective mass, plasma frequency, single oscillator strength and its position are then estimated as a function of alloy composition. It is interesting to note that the increase of Sn content on the parent Se90Te10 is connected to the decreasing covalent nature of the structure. Besides, the presence of such a sharp absorption edge in transmission spectra recommends Se90−xTe10Snx thin films as a good optical filter material.

The Effect of Sn addition in the structural and optical properties of Se–Te chalcogenide alloy at the expense of the Se content has been studied. Stoichiometric bulk ingot materials of the Se90−xTe10Snx (x=0, 2.5, 5 and 7.5 at%) were prepared by a melt-quench technique. X-ray diffraction (XRD) studies indicated that the investigated alloys confirmed its amorphous nature. These results were confirmed by scanning electron microscopy (SEM) investigations and correlated to the rigidity percolation threshold of the lattice. Stoichiometric thermally evaporated thin film of the obtained compositions were carefully characterized to establish the interdependence between their chemical composition and some physical parameters, such as the average heat of atomization (Hs), the cohesive energy CE, the average coordination number 〈Z〉 and the optical band gap (Eg). It has been found that all the parameters varied linearly when Sn content was increased. The variation in the optical band gap (Eg) with Sn addition was discussed in terms of the width of localized states (Ee) and a chemical bond approach model (CBA).