الفهرس 
Meaning of 2D-IMFs
Ac equivalent circuits of 2D-IMFsOnly 14 pages are availabe for public view
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Abstract
Name : Samy El-Gamal Mohammed El-Gamal
Title : “Effect of γ-radiation on the Electrical
Characterization of two dimensional Island
Metal films (2D-IMF)”
Submitted to: Physics Department, Faculty of Education, Ain
Shams University
Keywords: γ-irradiation, two-dimensional island platinum
films, electrical properties, sheet resistance and
the frequency-independent parameters
Four sets (A, B, C, and D) of two-dimensional island platinum films [2D-I(Pt)Fs] and five samples for each set of type I were prepared via the thermal evaporation technique. The mass thicknesses [dm] of the films of the different sets are 1, 5, 10, and 20 A°, respectively. The sheet resistance of these films was found experimentally from knowing the dc resistance of the films. Before exposing the films to γ-rays, we monitored the increase of the sheet resistance in air with time (aging) till short-term stability for the films was achieved. The stabilized films were exposed to γ-rays such that the different doses are 100, 200, 300, 500, and 700 Gy using 137Cs (0.662 MeV) radiation source with dose rate 0.5 Gy/min. It was found that; (i) the sheet resistance of the investigated films decreases with the increase of the dose, (ii) for any particular mass thickness, the value of the fractional change of sheet resistance increases with the increase of dose, (iii) for any particular dose the increase of the fractional change of sheet resistance becomes more pronounced with the increase of mass thickness. Also ac measurements were performed on these films. The frequency-independent parameters of one of the equivalent circuit for island metal films in general are Rb, Rg and Cg where Rb is the resistance of the islands themselves while Rg is the resistance that accompanies the transfer of electrons across the gaps among islands and Cg is the capacitance that results from the separated metallic islands. The least-square values of Rb, Rg and Cg at different doses were deduced for our films via a computerized analysis. It was found that (1) For any particular mass thickness: (a) Rb and Rg decreases with the increase of the dose of γ-rays while Cg increases (b) the absolute value of the fractional change of Rb, Rg and Cg increases with the increase of dose. (2) For any particular dose the increase of the fractional change of Rb, Rg and Cg becomes more pronounced when the mass thickness increases. Qualitative interpretation for our results was given on the ground that γ-rays changed the island’s shape from spherical to prolate spheroid one and this has been checked experimentally via imaging the films by Atomic Force Microscope before and after γ-irradiations. Finally, 2D-I(Pt)Fs were prepared by Joule heating [films of type II], which are characterized by larger islands compared with the films of type I. The dc and ac measurements conducted on films of type I before and after γ-irradiation were repeated on films of type II and we found that; (i) Films of type II are more stable than the ones of type I (ii) The values of the fractional change of , , and of films II are smaller than such values of films I