D Abdel-Hady

Bio: D Abdel-Hady is an academic researcher from Ain Shams University. The author has contributed to research in topics: Lattice constant & Dielectric. The author has an hindex of 1, co-authored 1 publications receiving 28 citations.

Optical properties of thermally vacuum evaporated thin films

Abstract: Silver antimony diselenide thin films were prepared by a thermal vacuum evaporation technique onto quartz and glass substrates kept at room temperature . The as-deposited films were amorphous and transformed to a face centred cubic (FCC) polycrystalline nature with the lattice constant on post-deposition annealing above 423 K for one hour in argon atmosphere. The optical constants (the refractive index n, and the absorption index k) of the films were determined for several samples of different thickness (180 nm-270 nm), using spectrophotometric measurements of the transmittance T and reflectance R at normal incidence in the spectral range 500-2500 nm. These constants were also determined for preannealed films, (polycrystalline). The obtained values of both n and k were independent of the film thickness within the above-mentioned thickness range. The refractive index data fitted a single-oscillator model with high-frequency dielectric constants increasing from 13 for the amorphous films to 15 for the crystalline films. It was found that the high-frequency dielectric constant has the same values as the lattice dielectric constant . The analysis of the spectral behaviour of the absorption coefficient in the intrinsic absorption region revealed the existence of an indirect allowed optical transition with energy gap 1.2 eV for amorphous films and 1.03 eV for the crystalline films, respectively.

Semiconducting AgSbSe2 thin film and its application in a photovoltaic structure

Abstract: Thin films of AgSbSe2 have been prepared by heating a Sb2S3–Ag stack, with the Ag side in contact with a chemically deposited Se thin film, which served as a planar source of Se vapour. A two-stage process, consisting of the formation of an Ag2Se film through the reaction of a vacuum deposited Ag film in the Se vapour at about 80 °C, and its reaction at 300 °C with a chemically deposited Sb2S3 film, results in the formation of the AgSbSe2 film. X-ray diffraction studies illustrate the structural evolution in the formation of this film. The material possesses an indirect optical band gap of about 0.9 eV. Thermoelectric measurements on the films showed a Seebeck coefficient of 500 µV K−1 (p-type), and thus a hole concentration of ~1022 m−3. The feasibility of application of these films as a photovoltaic absorber material is illustrated for the structure SnO2–CdS–(i)Sb2S3–(p)AgSbSe2, in which an open circuit voltage of 530 mV has been observed under an intensity of illumination of 2 kW m−2 using a tungsten–halogen lamp.