Physical Review B

我的台灣, 看見心靈的故鄉 =2009林磐聳藝術與設計展

Journal of Scientific Instruments Editor: Dr H R Lang Vol 28 and Supplement No 1, 1951 Pp xvi + 388 + iii + 80 (London: Institute of Physics, 1951) Bound, £3 12s; unbound, £3

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A Review of Scientific Instruments

Journal of Applied physics,Vol.33 : 1962年に発表されたレオロジー関連の論文

The impact-induced deposition of Al13 clusters with icosahedral structure on Ni(0 0 1) surface was studied by molecular dynamics (MD) simulation using Finnis–Sinclair potentials. The incident kinetic energy (Ein) ranged from 0.01 to 30 eV per atom. The structural and dynamical properties of Al clusters on Ni surfaces were found to be strongly dependent on the impact energy. At much lower energy, the Al cluster deposited on the surface as a bulk molecule. However, the original icosahedral structure was transformed to the fcc-like one due to the interaction and the structure mismatch between the Al cluster and Ni surface. With increasing the impinging energy, the cluster was deformed severely when it contacted the substrate, and then broken up due to dense collision cascade. The cluster atoms spread on the surface at last. When the impact energy was higher than 11 eV, the defects, such as Al substitutions and Ni ejections, were observed. The simulation indicated that there exists an optimum energy range, which is suitable for Al epitaxial growth in layer by layer. In addition, at higher impinging energy, the atomic exchange between Al and Ni atoms will be favourable to surface alloying.

Nuclear instruments and methods in physics research section B : beam interactions with materials and atoms

Influence of ammonia concentration on the microstructure, electrical and raman properties of low temperature chemical bath deposited ZnO nanorods

Hematite (alpha-Fe2O3) is a promising semiconductor as photoanode in solar hydrogen production from photoelectrolysis of water due to its appropriate band gap, low cost and high electrochemical stability in aqueous caustic electrolytes. Operation of such photoanode in a biased photoelectrochemical cell constitutes an anodization with consequent redox reactions at the electrode surface. alpha-Fe2O3 thin film photoanodes were prepared by simple and inexpensive dip coating method on fluorine doped tin oxide (FTO) glass substrate, annealed in air at 500 degrees C for 2 h, then electrochemically oxidized (anodized) in 1 M KOH at 500 mV for 1 min in dark and light conditions. Changes in structural properties and morphology of alpha-Fe2O3 nanoparticles films were investigated by XRD, Raman spectroscopy and a high resolution FESEM. The average grain size was observed to increase from similar to 57 nm for pristine samples to 73 and 77 nm for anodized samples in dark and light respectively. Broadening and red shift in Raman spectra in anodized samples may be attributed to lattice expansion upon oxidation. The UV-visible measurements revealed enhanced absorption in the photoanodes after the treatment. The findings suggest that the anodization of the photoelectrode in a biased cell causes not only changes of the molecular structure at the surface, but also changes in the crystallographic structure which can be detected with x-ray diffractometry. (C) 2015 Elsevier B.V. All rights reserved.

Morphology, structural and optical properties of iron oxide thin film photoanodes in photoelectrochemical cell: Effect of electrochemical oxidation

This paper reports on the deposition of pure and 5 at% Al doped ZnO (AZO) prepared by sol–gel and applied to the substrates by spin-coating, and the role of annealing temperature on the crystallinity of these layers It is found that both ZnO and AZO are largely amorphous when coated on glass compared to n-Si(111), as substrates On both substrates, X-ray diffraction (XRD) shows that the crystallinity improves as annealing temperature is raised from 200 to 600 °C with better crystallinity on Si substrates The thickness of the films on substrates was determined as 120 nm by Rutherford backscattering spectroscopy (RBS) Specular ultra-violet visible (UV–vis) gives the direct transition optical band gaps (Eg) for AZO as-deposited films are 260 and 335 eV while that of 600 °C annealed films are 300 and 360 eV The Eg calculated from diffuse reflectance spectroscopy (DRS) UV–vis are more diverse in ZnO- and AZO-Si than the ZnO- and AZO-glass samples, although in both sets the Eg tend to converge after annealing 600 °C The Raman spectra of samples show multiphonon processes of higher order from the AZO and substrates It is found that residual stresses are related to E2 Raman mode

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Role of substrate and annealing temperature on the structure of ZnO and AlxZn1−xO thin films for solar cell applications

In this study, the undoped, Erbium (Er) doped and Samarium (Sm) doped (1, 3, and 5 wt%) ZnO were synthesized using spray pyrolysis. X-ray diffraction patterns confirmed ZnO with strong diffraction peaks indexed in their right 2-theta angles. Raman spectroscopy observed A 1 , E 1 and E 2 vibrational phonon modes of wurtzite hexagonal ZnO. Scanning electron microscopy revealed nanoparticles that were well dispersed on the surface. There was agglomeration which was decreasing with an increase in the doping concentration from 1 to 5 wt% of Er and Sm. Energy-dispersive X-ray spectroscopy confirmed the main signals for Zn, O, Er, and Sm, with no other foreign elements observed. From the UV-Vis measurements, average transmittance of 74% at 550 nm was obtained for all the samples. The bandgap calculated for the thin films was decreasing from 3.31 eV for undoped ZnO to 2.96 eV and 3.11 eV for 5% Er and Sm doped samples, respectively. Schottky diodes were fabricated using aluminum (Al) and gold (Au) as the Schottky contact and palladium (Pd) as the Ohmic contact and electrical measurements performed. Both undoped and doped ZnO showed a rectifying behavior with an improvement in the rectification of up to almost 4 orders of magnitude for 5 wt% Er and Sm doped films compared to undoped ZnO which had a rectification of 2. In addition, the Schottky Barrier heights increased from 0.559 for undoped ZnO to 0.767 and 0.760 for 5 wt% Er and Sm doped, respectively. Undoped ZnO had an ideality factor of 2.49 which was decreased to 1.72 and 1.92 for Er and Sm doped ZnO devices. Also, a reduction in the leakage current and series resistance of devices was noted in undoped and doped ZnO. The fabricated devices can be used as an alternative for Schottky diode applications. 

Fred J. Nambala

Papers

Influence of ammonia concentration on the microstructure, electrical and raman properties of low temperature chemical bath deposited ZnO nanorods

Morphology, structural and optical properties of iron oxide thin film photoanodes in photoelectrochemical cell: Effect of electrochemical oxidation

Role of substrate and annealing temperature on the structure of ZnO and AlxZn1−xO thin films for solar cell applications

7[[7 A comparative study on the properties of Er Zn O and Sm Zn O nanostructured thin films for electronic device applications

A Comparative Study on the Properties of Er X Zn 1-X O and Sm X Zn 1-X O Nanostructured Thin Films for Electronic Device Applications