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Article Citation - WoS: 10Citation - Scopus: 11Dispersive Optical Constants of Thermally Deposited Agin5s8< Thin Films(Elsevier Science Sa, 2008) Qasrawi, A. F.Agln(5)S(8) thin films were obtained by the thermal evaporation of Agln(5)S(8) crystals onto ultrasonically cleaned glass substrates. The films are found to exhibit polycrystalline cubic structure. The calculated lattice parameter of the unit cell (a) is 10.78 angstrom. The transmittance data of the as grown films which was recorded at 300 K in the incidence wavelength (lambda) range of 320-1000 nm are used to calculate the refractive, n(lambda). The transmittance and reflectance data are also used to calculate the absorption coefficient of the as grown Agln5S8 thin films. The fundamental absorption edge is found to be corresponding to a direct allowed transitions energy band gap. This band-to-band transition energy is found to be 1.78 eV and it is consistent with that reported for Agln(5)S(8) single crystals. (c) 2007 Elsevier B.V. All rights reserved.Article Citation - WoS: 18Citation - Scopus: 19Temperature Dependence of the Direct Allowed Transitions Band Gap and Optical Constants of Polycrystalline Α-in2se3< Thin Films(Elsevier Science Sa, 2006) Qasrawi, A. F.Polycrystalline alpha-In2Se3 thin films were obtained by the thermal evaporation of alpha-In2Se3 crystals onto glass substrates kept at temperature of 200 degrees C. The temperature dependence of the optical band gap in the temperature region of 300-480 K and the room temperature refractive index, it (lambda), of these films have been investigated. The absorption edge shifts to lower energy values as temperature increases. The fundamental absorption edge corresponds to a direct allowed transitions energy gap that exhibits a temperature coefficient of -8.51 x 10(-4) (eV/K). The room temperature n(lambda) which was calculated from the transmittance data allowed the identification of the oscillator strength and energy, static dielectric constant and static refractive index as 20.7 and 2.15 eV, 10.70 and 3.26, respectively. (c) 2006 Elsevier B.V. All rights reserved.Article Citation - WoS: 28Citation - Scopus: 29Annealing Effects on the Structural and Optical Properties of Agin5s8< Thin Films(Elsevier Science Sa, 2008) Qasrawi, A. F.; Qasrawı, Atef Fayez Hasan; Qasrawı, Atef Fayez Hasan; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics EngineeringDue to its importance as a perspective material for application in optoelectronic semiconductor devices, the thermal annealing effects on the structural and optical properties of the as-grown vacuum evaporated AgIn5S8 thin films have been investigated. The X-ray data analysis have shown that these films are polycrystalline in nature and exhibit better crystallization with increasing crystallite size and slightly, decreasing unit cell lattice parameter as annealing temperature is raised from 450 to 600 K. The optical energy band gap for the as-grown and thermally annealed films is found to be of direct allowed transitions type. The energy band gap exhibited values of 1.78, 1.74 and 1.62 eV as the samples were annealed at, 450 and 600 K, respectively. This indicates the ability of altering the band gap values of this material by the thermal annealing process. The structural and optical features seem to be suitable for semiconductor device production such as solar cell converters, which has successfully been fabricated by others, metal-insulator-semiconductor (MIS) and metal - oxide - semiconductor (MOS) devices, as well. (c) 2007 Elsevier B.V. All rights reserved.
