Dahlang Tahir

Bio: Dahlang Tahir is an academic researcher from Hasanuddin University. The author has contributed to research in topics: Materials science & Fourier transform infrared spectroscopy. The author has an hindex of 17, co-authored 113 publications receiving 1201 citations. Previous affiliations of Dahlang Tahir include Chungbuk National University.

Electronic and optical properties of Cu, CuO and Cu2O studied by electron spectroscopy

Abstract: The electronic and optical properties of Cu, CuO and Cu(2)O were studied by x-ray photoelectron spectroscopy (XPS) and reflection electron energy-loss spectroscopy (REELS). We report detailed Cu 2p, Cu LVV, O 1s and O KLL spectra which are in good agreement with previous results. REELS spectra, recorded for primary energies in the range from 150 to 2000 eV, were corrected for multiple inelastically scattered electrons to determine the effective inelastic scattering cross section. The dielectric functions and optical properties were determined by comparing the experimental inelastic electron scattering cross section with a simulated cross section calculated within the semi-classical dielectric response model in which the only input is Im(-1/e) by using the QUEELS-e(k,ω)-REELS software package. By Kramers-Kronig transformation of the determined Im(-1/e), the real and imaginary parts (e(1) and e(2)) of the dielectric function, and the refractive index n and extinction coefficient k were determined for Cu, CuO, and Cu(2)O in the 0-100 eV energy range. Observed differences between Cu, CuO and Cu(2)O are mainly due to modifications of the 3d and O 2p electron configurations.

Electronic and optical properties of Al2O3/SiO2 thin films grown on Si substrate

Abstract: The electronic and optical properties of Al2O3/SiO2 dielectric thin films grown on Si(1 0 0) by the atomic layer deposition method were studied by means of x-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy (REELS) The band gaps of the Al2O3/SiO2 thin films before annealing and after annealing were 65 eV and 75 eV, respectively, and those of the γ-Al2O3 and α-Al2O3 phases were 71 eV and 84 eV, respectively All of these were estimated from the onset values of the REELS spectra The dielectric functions were determined by comparing the effective cross-section determined from experimental REELS with a rigorous model calculation based on dielectric response theory, using available software packages The determined energy loss function obtained from the Al2O3/SiO2 thin films before annealing showed a broad peak at 227 eV, which moved to the γ-Al2O3 position at 243 eV after annealing The optical properties were determined from the dielectric function The optical properties of the Al2O3/SiO2 thin films after annealing were in good agreement with those of γ-Al2O3 The changes in band gap, electronic and optical properties of the Al2O3/SiO2 thin films after annealing indicated a phase transition from an amorphous phase to the γ-Al2O3 phase after annealing

Band alignment of atomic layer deposited (ZrO2)x(SiO2)1−x gate dielectrics on Si (100)

Abstract: The band alignment of atomic layer deposited (HfZrO4)1−x(SiO2)x (x = 0, 0.10, 0.15, and 0.20) gate dielectric thin films grown on Si (100) was obtained by using X-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy. The band gap, valence band offset, and conduction band offset values for HfZrO4 silicate increased from 5.4 eV to 5.8 eV, from 2.5 eV to 2.75 eV, and from 1.78 eV to 1.93 eV, respectively, as the mole fraction (x) of SiO2 increased from 0.1 to 0.2. This increase in the conduction band and valence band offsets, as a function of increasing SiO2 mole fraction, decreased the gate leakage current density. As a result, HfZrO4 silicate thin films were found to be better for advanced gate stack applications because they had adequate band gaps to ensure sufficient conduction band offsets and valence band offsets to Si.

X-ray diffraction analysis of nanocomposite Fe3O4/activated carbon by Williamson–Hall and size-strain plot methods

Abstract: Analysis X-ray diffraction (XRD) spectra of nanocomposite Fe3O4/activated carbon (AC) to determine the crystallite size have been carried out by using various calculations methods; Scherrer, Williamson–Hall (W–H), and Size-Strain plot (SSP). Williamson–Hall (W–H) methods were used three type models; uniform deformation model (UDM), uniform stress deformation model (USDM), and uniform deformation energy density model (UDEDM) which were resulting new important parameters including stress ( σ ), lattice strain ( e ), and energy density (u). Crystallite size is decreases with increasing the amount of AC in the nanocomposites due to the lattice strain and dislocations from the rearrangement bonding connection between the atoms of Fe3O4 and the AC which were confirmed by using TEM (Transmission Electron Microscope) image. SSP method in this study shows good agreement with the TEM analysis compared with other methods. In the present paper, we provided for the first time, the crystallite size of nanocomposite Fe3O4/activated carbon (AC) materials by using various methods in the analysis of XRD spectra.

Electronic and optical properties of selected polymers studied by reflection electron energy loss spectroscopy

Abstract: We have determined the electronic and optical properties of six polymers: Polymethyl-methacrylate (PMMA), polyethylene (PE), polyvinyl chloride (PVC), polyester (PET), polypyrrole (PPY), and polyamide (PA6) for energy losses from 0 to 70 eV by analysis of reflection electron energy-loss spectroscopy (REELS) spectra. We found that the surface was easily damaged by the incident electron beam, in particular for energies above 500 eV. The damage results in new peaks in the bandgap region and the polymers become metallic. Great care was exerted to determine experimental conditions under which these effects are minimized. The REELS spectra were corrected for multiple inelastically scattered electrons with the QUASES-XS-REELS software to determine the effective inelastic-scattering cross sections. From these cross sections, we found that the band gaps for PMMA, PE, PVC, PET, PPY, and PA6 are 5.0 eV, 7.5 eV, 7.0 eV, 3.0 eV, 3.5 eV, and 5.1 eV, respectively. Quantitative analysis of the experimental cross sections was carried out by using the QUEELS-ɛ(k,ω)-REELS software to determine the dielectric function and optical properties. This is done by comparing the experimental REELS inelastic electron-scattering cross-section with a simulated cross section in which the only input is Im(−1/ɛ). The dielectric function is expressed as a sum of oscillators and the oscillator parameters are determined. Good agreement between the experimental and theoretical cross section is achieved for all polymers. From Im(−1/ɛ), the real and imaginary parts of ɛ (ω), the refractive index, and the extinction coefficient were determined for all polymers in the energy range ћω = 0 to 70 eV. An oscillator is clearly observed for PPY, PET, and PA6 at ∼ 6.7 eV, which corresponds to the π plasmon. This oscillator is not found for PMMA, PE, and PVC. A set of oscillators in the 20–30 eV energy range corresponding to the σ+π plasmon is found for all polymers.

Mitigation and Adaptation Strategies for Global Change

Abstract: ▶ Addresses a wide range of timely environment, economic and energy topics ▶ A forum to review, analyze and stimulate the development, testing and implementation of mitigation and adaptation strategies at regional, national and global scales ▶ Contributes to real-time policy analysis and development as national and international policies and agreements are discussed and promulgated ▶ 94% of authors who answered a survey reported that they would definitely publish or probably publish in the journal again

Crystallinity of inorganic films grown by atomic layer deposition: Overview and general trends

Abstract: Atomic layer deposition (ALD) is gaining attention as a thin film deposition method, uniquely suitable for depositing uniform and conformal films on complex three-dimensional topographies. The deposition of a film of a given material by ALD relies on the successive, separated, and self-terminating gas–solid reactions of typically two gaseous reactants. Hundreds of ALD chemistries have been found for depositing a variety of materials during the past decades, mostly for inorganic materials but lately also for organic and inorganic–organic hybrid compounds. One factor that often dictates the properties of ALD films in actual applications is the crystallinity of the grown film: Is the material amorphous or, if it is crystalline, which phase(s) is (are) present. In this thematic review, we first describe the basics of ALD, summarize the two-reactant ALD processes to grow inorganic materials developed to-date, updating the information of an earlier review on ALD [R. L. Puurunen, J. Appl. Phys. 97, 121301 (2005)], and give an overview of the status of processing ternary compounds by ALD. We then proceed to analyze the published experimental data for information on the crystallinity and phase of inorganic materials deposited by ALD from different reactants at different temperatures. The data are collected for films in their as-deposited state and tabulated for easy reference. Case studies are presented to illustrate the effect of different process parameters on crystallinity for representative materials: aluminium oxide, zirconium oxide, zinc oxide, titanium nitride, zinc zulfide, and ruthenium. Finally, we discuss the general trends in the development of film crystallinity as function of ALD process parameters. The authors hope that this review will help newcomers to ALD to familiarize themselves with the complex world of crystalline ALD films and, at the same time, serve for the expert as a handbook-type reference source on ALD processes and film crystallinity.

Magnetic Resonance Imaging Physical Principles And Sequence Design

Abstract: Thank you for downloading magnetic resonance imaging physical principles and sequence design. As you may know, people have look numerous times for their chosen books like this magnetic resonance imaging physical principles and sequence design, but end up in harmful downloads. Rather than enjoying a good book with a cup of coffee in the afternoon, instead they juggled with some malicious bugs inside their laptop.

Electronic and optical properties of Cu, CuO and Cu2O studied by electron spectroscopy

Abstract: The electronic and optical properties of Cu, CuO and Cu(2)O were studied by x-ray photoelectron spectroscopy (XPS) and reflection electron energy-loss spectroscopy (REELS). We report detailed Cu 2p, Cu LVV, O 1s and O KLL spectra which are in good agreement with previous results. REELS spectra, recorded for primary energies in the range from 150 to 2000 eV, were corrected for multiple inelastically scattered electrons to determine the effective inelastic scattering cross section. The dielectric functions and optical properties were determined by comparing the experimental inelastic electron scattering cross section with a simulated cross section calculated within the semi-classical dielectric response model in which the only input is Im(-1/e) by using the QUEELS-e(k,ω)-REELS software package. By Kramers-Kronig transformation of the determined Im(-1/e), the real and imaginary parts (e(1) and e(2)) of the dielectric function, and the refractive index n and extinction coefficient k were determined for Cu, CuO, and Cu(2)O in the 0-100 eV energy range. Observed differences between Cu, CuO and Cu(2)O are mainly due to modifications of the 3d and O 2p electron configurations.