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Ikhmayies S.J.,Isra University of Jordan | Ahmad-Bitar R.N.,University of Jordan
Materials Science in Semiconductor Processing | Year: 2013

Polycrystalline cadmium telluride (CdTe) thin films were prepared by vacuum evaporation on glass substrates at ambient temperature. X-ray diffraction pattern (XRD) showed that the films are polycrystalline with predominant zinc blend structure. A strong reflection from the (111) plane of the cubic phase was seen beside two weak reflections from the (220) and (311) planes of the same phase. Three very weak lines that are characteristic of elemental tellurium were also observed. The average grain size was estimated by using Sherrer's formula and found to be 24±1 nm. The scanning electron microscope (SEM) image showed a uniform surface with submicron grain size. The difference between grain size obtained from Sherrer's formula and that observed in the SEM micrograph means that each grain consists of a large number of smaller crystallites. The composition of the films was explored by using energy dispersive spectroscopy (EDS), which revealed that the surfaces of the films have excess tellurium. The transmittance was measured in the wavelength range λ=400-1100 nm and used to estimate the optical bandgap energy Eg which was found to be Eg=1.48±0.01 eV. The absorption coefficient was calculated and plotted against the photon's energy and tailing in the bandgap was observed. This tailing was found to follow the empirical Urbach rule. The width of the tail was estimated and related to localized states. The linear current-voltage (I-V) plots were used to find the resistivity ρ, where a value of ρ=2.10×106 Ω cm was obtained. © 2012 Elsevier Ltd.

Al-Khresheh M.H.,Isra University of Jordan
International Journal of Applied Linguistics and English Literature | Year: 2015

The influence of first language (L1 hereinafter) in the learning of second language (L2 hereinafter) has witnessed an intense debate during the past years, resulting in the prevalence of Error Analysis (EA hereinafter) over Contrastive Analysis (CA hereinafter). A great number of empirical studies indicated that neither L1 nor L2 was always responsible for learners' errors (Bailey et al. 1974; Krashen et al. 1978, 2003; Larsen-Freeman, 2002; 2003). CA and EA paved the way for Interlanguage theory (IL hereinafter) in describing L2 learners' errors in the acquisition process of L2. IL, which has been in vogue for the last years, has witnessed huge criticism by different researchers and linguists from various L1 backgrounds. They all came to state that there are many points in this theory which are not clear. In light of this, this study aims at reviewing and discussing the role of IL in describing and explaining learners' errors in the process of acquisition of L2. Therefore, theoretical foundations, theoretical assumptions, limitations and significance of this theory are discussed in detail. This review reveals that IL theory is almost no longer valid in the field of second language acquisition (SLA hereinafter) for numerous reasons. © 2015, Australian International Academic Centre PTY LTD. All rights reserved.

Ikhmayies S.J.,Isra University of Jordan
Journal of Electronic Materials | Year: 2016

Zinc oxide (ZnO) microrods were synthesized by the spray pyrolysis technique on aluminum substrates at a substrate temperature of 350 ± 5°C. The samples were characterized by x-ray diffraction (XRD), x-ray fluorescence (XRF), scanning electron microscopy (SEM), and energy dispersion x-ray spectroscopy (EDX). XRD diffractograms presented the wurtzite (hexagonal) structure with (002) as the preferential orientation. The SEM observations showed typical microrods of hexagonal cross sections with lengths in the range 1.0–2.5 μm and diameter in the range 300–400 nm. XRF and EDX analysis revealed that the samples contain chlorine, and other impurities, which are related to the aluminum substrate and the starting material zinc chloride (ZnCl2). It is found that the microrods are rich in oxygen, which make them of potential use in gas sensors, besides solar cells, lithium ion batteries and other electo-optic devices. © 2016 The Minerals, Metals & Materials Society

Ikhmayies S.J.,Isra University of Jordan | Ahmad-Bitar R.N.,University of Jordan
Vacuum | Year: 2011

An investigation of selected contacts for indium doped cadmium sulphide (CdS:In) thin films was performed through the analysis of the I-V characteristics in the dark and room light at room temperature. Indium, aluminum and silver were selected as contacts where two strips of each metal were vacuum- evaporated on the surface of the film. All of these metals could form ohmic contacts, but indium had shown the best characteristics then aluminum. Films with indium contacts gave the best electrical properties and they are slightly affected by light. Doping and annealing were found to improve the contacts as seen in the I-V plots because they are expected to reduce the contact potential and annealing helps in the formation of an alloy with the semiconductor which forms an ohmic contact. © 2011 Elsevier Ltd. All rights reserved.

Afaneh S.,Isra University of Jordan | Zitar R.A.,University of Jordan | Al-Hamami A.,Amman Arab University
Applied Soft Computing Journal | Year: 2013

This paper presents a novel approach for computer viruses detection based on modeling the structures and dynamics of real life paradigm that exists in the bodies of all living creatures. It aims to develop an algorithm based on the concept of the artificial immune system (AIS) for the purpose of detecting viruses. The algorithm is called Virus Detection Clonal algorithm (VDC), and it is derived from the clonal selection algorithm. The VDC algorithm consists of three basic steps: cloning, hyper-mutation and stochastic re-selection. In later stage, the developed VDC algorithm is subjected to validation, which consists of two phases; learning and testing. Two main parameters are determined; one of them is setting the number of signatures per clone (Fat), while the other defines the hypermutation probability (Pm). Later on, the Genetic Algorithm (GA) is used as a tool, to improve the developed algorithm by searching the values of the main parameters (Fat and Pm) to reproduce better results. The results have shown that the detection rate of viruses, by using the developed algorithm, is 94.4%, whereas the detection rate of false positives has reached 0%. These percentages indicate that the VDC algorithm is sufficient and usable in this field. Moreover, the results of employing the GA to optimize the VDC algorithm have shown an improvement in the detection speed of the algorithm. © 2012 Elsevier B.V.

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