Ahmed M. Nawar

Semiconducting properties of Al doped ZnO thin films

Aluminum doped ZnO (AZO) thin films were successfully deposited via spin coating technique onto glass substrates. Structural properties of the films were analyzed by X-ray diffraction, atomic force microscopy (AFM) and energy dispersive X-ray spectroscopy. X-ray diffraction results reveal that all the films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the direction (002) plane. The crystallite size of ZnO and AZO films was determined from Scherrers formula and Williamson-Hall analysis. The lattice parameters of the AZO films were found to decrease with increasing Al content. Energy dispersive spectroscopy (EDX) results indicate that Zn, Al and O elements are present in the AZO thin films. The electrical conductivity, mobility carriers and carrier concentration of the films are increased with increasing Al doping concentration. The optical band gap (Eg) of the films is increased with increasing Al concentration. The AZO thin films indicate a high transparency in the visible region with an average value of 86%. These transparent AZO films may be open a new avenue for optoelectronic and photonic devices applications in near future.

Effect ofX-ray Irradiation on Structural and Optical Properties of Topological Insulator Bismuth Telluride Nano-Structure Thin Film

Bismuth Telluride (Bi2Te3) thin films were grown ontooptical flat fused quartz and chronic glass by using a thermal evaporation technique for optical and structural investigations, respectively.The prepared films were divided into three groups; the first group was as-grown films, and the second and third groups were irradiated with X-ray radiation with energies 6 and 15 MeV.The crystal structure and morphology of the grown Bi2Te3thin films were identified by X-ray diffraction (XRD) and scan electron microscopy (SEM) before and after exposed to X-ray irradiation. The optical constants(Refractive index, n, and absorption index, k) of as- grown and irradiated Bi2Te3 thin films were estimated and calculated in the wavelength range from 200 to 2500 nm by using spectrophotometric measurements of transmittance and reflectance at normal incidence. The estimated onset optical gap Egfor as-grown equal to 0.35 eV and this value was found to be decreased corresponding to the increasing in X-ray radiation energy.The variation of the refractive index of normal dispersion is well described by the single oscillator model. The dielectric constant at infinite frequency (e∞), the lattice dielectric constant (eL) and the ratio of free carrier concentration of the effective mass (N/m*) are calculated. Finally, the nonlinear optical parameters are calculated using some empirical relations.

Improving the optical and electrical properties of Zinc Oxide thin film by Cupric Oxide dopant

Abstract : ZnO and ZnO/CuO nanocomposite were successfully synthesized by Sol-Gel technique. The crystal structure was investigated by X- ray diffraction technique and the molecular structure was studied by Fourier transformation infrared. Atomic force microscopy was used to study the topological properties of the prepared thin films. The optical properties were studied and the optical band gap were evaluated from the x-axis intercepts at (αhυ) 2 =0 and found to be decreased from 3.27 to 3.26 eV as the dopant increased. ZnO and ZnO/CuO nanocomposite were used as interfacial layer on schottky diode. The technical parameters such as ideality factor and the barrier height were found to be increased from 3.7 to 6.5 and from 0.59 to 0.62 eV respectively as the dopant were increased. Keywords: ZnO; CuO; Composite; optical Properties; Schottky diode; I. Introduction Nanostructured metal-oxide semiconductor materials have been widely studied due to their electronic, optical, optoelectronic properties and potential applications in nanoscale devices. These materials offer many new opportunities to study fundamental surface processes in a controlled manner and this, in turn, leads to fabrication of new devices. Great interest has been shown in the preparation of nanomaterials, particularly oxides. Transparent conductive oxides (TCOs) such as Zinc Oxide (ZnO), Cadmium Oxide (CdO), Tin Oxide (SnO