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Tipperary, Ireland

Lynch R.P.,University of Limerick | O'Dwyer C.,University of Limerick | O'Dwyer C.,University College Cork | O'Dwyer C.,Tyndall National Institute | And 5 more authors.
Journal of the Electrochemical Society | Year: 2013

Pore propagation during anodization of (100) n-InP electrodes in aqueous KOH was studied in detail by scanning and transmission electron microscopy (SEM and TEM). Pores emanating from surface pits propagate along the μ111μA crystallographic directions to form, in the early stages of anodization, porous domains with the shape of a tetrahedron truncated symmetrically through its center by a plane parallel to the surface of the electrode. This was confirmed by comparing the predictions of a detailed model of pore propagation with SEM and TEM observations. The model showed in detail how μ111μA pore propagation leads to domains with the shape of a tetrahedron truncated by a (100) plane. Observed cross sections corresponded in detail and with good precision to those predicted by the model. SEM and TEM showed that cross sections were trapezoidal and triangular, respectively, in the two cleavage planes of the wafer, and TEM showed that they were rectangular parallel to the surface plane, as predicted. Aspect ratios and angles calculated from observed cross sections were in good agreement with predicted values. The pore patterns observed were also in good agreement with those predicted and SEM observations of the surface further confirmed details of the model. © 2013 The Electrochemical Society. All rights reserved. Source

Salaun A.,Tyndall National Institute | Salaun A.,University College Cork | Newcomb S.B.,Glebe Scientific Ltd. Newport | Povey I.M.,Tyndall National Institute | And 4 more authors.
Chemical Vapor Deposition | Year: 2011

We describe the formation of RuO 2 thin films grown using atomic layer deposition (ALD) on (100) Si substrates from Ru(EtCp) 2 and O 2, and the subsequent influence of annealing temperature and atmosphere on the surface morphology and structure of the deposited layers. The films are characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and electron diffraction (ED). The as-deposited films consist of RuO 2 islands. No significant changes in composition or morphology are observed following annealing in N 2 for 4 h at either 500 or 700°C. Higher temperature annealing in N 2 (820°C, 4 h) results in some modifications to the morphology and structure where ED data indicate the formation of some Ru metal. However, complete transformation from as-deposited RuO 2 to Ru metal is, obtained after annealing in forming gas (95% N 2/5% H 2) at 420°C for 5 min. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

O'Connor E.,Tyndall National Institute | Brennan B.,Dublin City University | Contreras R.,CINVESTAV | Milojevic M.,University of Texas at Dallas | And 7 more authors.
ECS Transactions | Year: 2010

In this work we present the results of an investigation into the effectiveness of varying (NH4)2S concentrations in the passivation of n-type and p-type In0.53Ga0.47As, as determined through analysis of electrical properties. Samples were degreased and immersed in aqueous (NH4)2S solutions of concentrations 22%, 10%, 5%, or 1% for 20 minutes at 295K, immediately prior to ALD growth. Capacitance-voltage analysis of Au/Ni/Al2O3/In 0.53Ga0.47As structures indicate that the lowest frequency dispersion over the bias range examined occurs for n and p-type devices treated in 10% (NH4)2S solution. The deleterious effect on interface state density of increased ambient exposure time after removal from (NH4)2S solution is also presented. Estimations of peak interface state density, Dit, extracted from the equivalent parallel conductance Gp, using an approximation to the conductance method, are used for comparison of the different passivation conditions. ©The Electrochemical Society. Source

Salaun M.,Tyndall National Institute | Corbett B.,Tyndall National Institute | Newcomb S.B.,Glebe Scientific Ltd. Newport | Pemble M.E.,Tyndall National Institute
Journal of Materials Chemistry | Year: 2010

Photonic crystals made from noble metals such as silver are an interesting class of material for many applications such as chemical sensing, solar cells or photonics. Their fabrication suffers from a lack of reproducibility, and complicated and aggressive processes. In this paper we show a simple and reproducible method based on the black and white photography process, to get a self standing 3D silver photonic crystal. Their characterization by SEM and TEM allowed us to interpret the process, and optical analysis made in reflection and transmission were used to find out eventual coupling between surface plasmon polaritons and the photonics properties of the structure itself. © 2010 The Royal Society of Chemistry. Source

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