Optical absorption at room temperature and electrical resistivity at temperatures between 200 and 320 K for (As.Te)1-xSex thin films (where x=0.20, 0.23, 0.27, 0.32 and 0.44) have been studied. Increasing the Se content was found to increase the optical energy gap and the activation energy for conduction of the investigated films. The optical energy gap of the As0.40Te0.40Se0.20 films was increased up to 1.21 eV by increasing the film thickness to 120 nm, while thermal annealing at 480 K reduced it down to 0.83 eV. The decrease of the optical gap is discussed on the basis of amorphous-crystalline transformations.

Optical absorption at room temperature and electrical resistivity at temperatures between 200 and 320 K for (As.Te)1-xSex thin films (where x=0.20, 0.23, 0.27, 0.32 and 0.44) have been studied. Increasing the Se content was found to increase the optical energy gap and the activation energy for conduction of the investigated films. The optical energy gap of the As0.40Te0.40Se0.20 films was increased up to 1.21 eV by increasing the film thickness to 120 nm, while thermal annealing at 480 K reduced it down to 0.83 eV. The decrease of the optical gap is discussed on the basis of amorphous-crystalline transformations.

Optical absorption at room temperature and electrical resistivity at temperatures between 200 and 320 K for (As.Te)1-xSex thin films (where x=0.20, 0.23, 0.27, 0.32 and 0.44) have been studied. Increasing the Se content was found to increase the optical energy gap and the activation energy for conduction of the investigated films. The optical energy gap of the As0.40Te0.40Se0.20 films was increased up to 1.21 eV by increasing the film thickness to 120 nm, while thermal annealing at 480 K reduced it down to 0.83 eV. The decrease of the optical gap is discussed on the basis of amorphous-crystalline transformations.

Glassy As45.2Te46.6In8.2 thin films were thermally evaporated onto chemically cleaned glass substrates. Crystallization kinetics were determined under isothermal conditions. Heating the film up to the isothermal temperature with different rates was found to yield films with different electrical characterization. Conductivity of the investigated film was used as a parameter indicating the crystallized fraction χ(t). The obtained values of the activation energy for crystallization, the frequency factor and the Avrami index are (100±0.5) kJ/mol, (7.31±0.04) 108 s−1 and 1.45, respectively. The non-integer value of the Avrami index indicates that two crystallization mechanisms are responsible for the crystal growth

Glassy As45.2Te46.6In8.2 thin films were thermally evaporated onto chemically cleaned glass substrates. Crystallization kinetics were determined under isothermal conditions. Heating the film up to the isothermal temperature with different rates was found to yield films with different electrical characterization. Conductivity of the investigated film was used as a parameter indicating the crystallized fraction χ(t). The obtained values of the activation energy for crystallization, the frequency factor and the Avrami index are (100±0.5) kJ/mol, (7.31±0.04) 108 s−1 and 1.45, respectively. The non-integer value of the Avrami index indicates that two crystallization mechanisms are responsible for the crystal growth

Glassy As45.2Te46.6In8.2 thin films were thermally evaporated onto chemically cleaned glass substrates. Crystallization kinetics were determined under isothermal conditions. Heating the film up to the isothermal temperature with different rates was found to yield films with different electrical characterization. Conductivity of the investigated film was used as a parameter indicating the crystallized fraction χ(t). The obtained values of the activation energy for crystallization, the frequency factor and the Avrami index are (100±0.5) kJ/mol, (7.31±0.04) 108 s−1 and 1.45, respectively. The non-integer value of the Avrami index indicates that two crystallization mechanisms are responsible for the crystal growth

Measurements of absorbance and transmittance in Ge20Se80-xBix (0 x 10 at %) chalcogenide thin films in the visible range at room temperature were carried out. The dependence of the optical absorption on the photon energy is described by the relation hv=B(hv-E0)2. It was found that the optical energy gap E0 decreases gradually from 1.93 to 1.205 eV with increasing Bi content up to 10 at %. The rate of the change decreases with increasing Bi content. The composition dependence of the optical energy gap is discussed on the basis of the concentration of covalent bonds formed in the chalcogenide film. The decrease of optical energy gap with increasing Bi content is related to the increase of Bi–Se bonds and the decrease of Se-Se bonds. The effect of thermal annealing for different periods of time on the behavior of optical absorption of the as-deposited films was investigated. The optical gap increases with increasing annealing time. The rate of change decreases with increasing annealing time, then E0 reaches a steady state. The increase in the values of the optical gap of the amorphous films with heat treatment is interpreted in terms of the density of states model. The structure of the as-prepared and thermally annealed films were investigated using transmission electron microscopy, energy dispersive analysis and X-ray diffraction. It was confirmed that the as-prepared films were in the amorphous state. Phase separation was observed after thermal annealing. The separated crystalline phases were identified.

The microstructure of electron beam deposited Bi3Se100 thin films (where x varies from 0 to 16 at.%) was investigated. The morphology of crystallization for in situ thermally annealed and electron beam heated Bi16Se84 films was investigated using transmission electron microscopy. Selected area electron diffraction was used to characterize different phases observed during the crystallization process where the crystalline Bi2Se3 phase was separated. Optical absorption measurements were carried out on as-deposited BixSe100-x films of different compositions. It was found that the mechanism of the optical absorption follows the rule of non-direct transition. The optical energy gap decreases with increasing Bi content. The effect of thermal annealing on the optical properties of Bi16Se84 films was investigated. The study indicated that Bi16Se84 films have low threshold energy for amorphization, high optical absorption coefficient and optimum contrast between the amorphous and the crystalline states. The decrease in the optical gap is discussed on the basis of amorphous-crystalline transformations

Thermal co-evaporation technique (from two sources — Cu wire and In30Se70 ingots) was used to prepare CuInSe thin films. Controlling the evaporation rates from the sources was helpful to get films having different Cu/In content. The temperature dependence of the electrical conductivity was investigated in the temperature range 80 K≤T≤435 K. The density of localized states at the Fermi level and the activation energy for conduction are decreased on increasing the film (Cu/In) content. The activation energy for conduction of the Cu20In20Se60 film decreases on increasing the annealing temperature. Tetragonal CuInSe2 and hexagonal Cu2Se crystalline phases resulting from heat treatment have been identified using X-ray diffractometry and transmission electron microscope

As30Te70−xGax (x=0.5, 1, 3, 6 and 10 at.%) chalcogenide thin films were studied. Specimens of thickness 2500 Å were used for resistivity (ρ) measurements as a function of temperature (T) in the temperature range from 300 to 443 K. The resistivity (ρ) exhibits an activated temperature dependence in accordance with the relation ρ(T)=ρ0 exp(ΔE/kT). It was found that the activation energy for conduction (ΔE) and room temperature resistivity (ρ300) decrease with increasing Ga content up to 3 at.%. For x greater than 3 at.%, it was found that ΔE and ρ300 increase with increasing Ga content. The results were discussed according to the valence alternation pair (VAP) model and the alloying effect. Thermal annealing above Tg was found to decrease ρ and ΔE. The decrease of ρ and ΔE after annealing at T>Tg was attributed to the amorphous–crystalline transformation. XRD, SAED, TEM and DSC were used to study the structure of the as-deposited and annealed films