Abstract: Gas discharge plasmas are used for a wide range of applications. To improve our understanding about gas discharges, which is necessary to obtain good results in the various application fields, we perform numerical modelling of gas discharge plasmas. Various kinds of modelling approaches, for various types of gas discharges, are being used in our group. In this paper, some examples of this modelling work are outlined. (C) 2002 Elsevier Science Ltd. All rights reserved.

Abstract: Epitaxially grown ultra-thin Si layers are often used to passivate Ge surfaces in the high-k gate module of (strained) Ge FinFET and Gate All Around devices. We use Si4H10 as Si precursor as it enables epitaxial Si growth at temperatures down to 330 degrees. C-V characteristics of blanket capacitors made on Ge virtual substrates point to the presence of an optimal Si thickness. In case of compressively strained Ge fin structures, the Si growth results in non-uniform and high strain levels in the strained Ge fin. These strain levels have been calculated for different shapes of the Ge fin and in function of the grown Si thickness. The high strain is the driving force for potential (unwanted) Ge surface reflow during Si deposition. The Ge surface reflow is strongly affected by the strength of the H-passivation during Si-capping and can be avoided by carefully selected process conditions. (C) The Author(s) 2018. Published by ECS.

Abstract: Heavily P doped Si:P epitaxial layers have gained interest in recent times as a promising source-drain stressor material for n type FinFETs (Fin Field Effect Transistors). They are touted to provide excellent conductivity as well as tensile strain. Although the as-grown layers do provide tensile strain, their conductivity exhibits an unfavorable behavior. It reduces with increasing P concentration (P > 1E21 at/cm(3)), accompanied by a saturation in the active carrier concentration. Subjecting the layers to laser annealing increases the conductivity and activates a fraction of P atoms. However, there is also a concurrent reduction in tensile strain (<1%). Literature proposes the formation of local semiconducting Si3P4 complexes to explain the observed behaviors in Si:P [Z. Ye et al., ECS Trans., 50(9) 2013, p. 1007-10111. The development of tensile strain and the saturation in active carrier is attributed to the presence of local complexes while their dispersal on annealing is attributed to strain reduction and increase in active carrier density. However, the existence of such local complexes is not proven and a fundamental void exists in understanding the structure-property correlation in Si:P films. In this respect, our work investigates the reason behind the evolution of strain and electrical properties in the as-grown and annealed Si:P epitaxial layers using ab-initio techniques and corroborate the results with physical characterization techniques. It will be shown that the strain developed in Si:P films is not due to any specific complexes while the formation of Phosphorus-vacancy complexes will be shown responsible for the carrier saturation and the increase in resistivity in the as-grown films. Interstitial/precipitate formation is suggested to be a reason for the strain loss in the annealed films. (C) The Author(s) 2018. Published by ECS.

Abstract: After a short review of electron tomography techniques for materials science, this overview will cover some recent results on different shape memory and nanostructured metallic systems obtained by various three-dimensional (3D) electron imaging techniques. In binary NiTi, the 3D morphology and distribution of Ni4Ti3 precipitates are investigated by using FIB/SEM slice-and-view yielding 3D data stacks. Different quantification techniques will be presented including the principal ellipsoid for a given precipitate, shape classification following a Zingg scheme, particle distribution function, distance transform and water penetration. The latter is a novel approach to quantifying the expected matrix transformation in between the precipitates. The different samples investigated include a single crystal annealed with and without compression yielding layered and autocatalytic precipitation, respectively, and a polycrystal revealing different densities and sizes of the precipitates resulting in a multistage transformation process. Electron tomography was used to understand the interaction between focused ion beam-induced Frank loops and long dislocation structures in nanobeams of Al exhibiting special mechanical behaviour measured by on-chip deposition. Atomic resolution electron tomography is demonstrated on Ag nanoparticles in an Al matrix.

Abstract: Metamorphic buffers (M-buffers) consisting of graded InAlAs or bulk InP were employed for the production of InP-based epiwafers on GaAs substrates by molecular-beam epitaxy. The graded InAlAs is the standard for production metamorphic high electron mobility transistors (M-HEMTs), while the bulk InP offers superior thermal properties for higher current density circuits. The surface morphology and crystal structure of the two M-buffers showed different relaxation mechanisms. The graded InAlAs gave a cross-hatched pattern with nearly full relaxation and very effective dislocation filtering, while the bulk InP had a uniform isotropic surface with dislocations propagating further up towards the active layers. Both types of M-buffers had atomic force microscopy root-mean-square roughness values around 2030 Å. The Hall transport properties of high electron mobility transistors (HEMTs) grown on the InAlAs M-buffer, and a baseline HEMT grown lattice matched on InP, both had room-temperature mobilities >10 000 cm2/V s, while the M-HEMT on the InP M-buffer showed a decrease to 9000 cm2/V  s. Similarly, the dc parameters of a double heterojunction bipolar transistor (DHBT) grown on the InAlAs M-buffer were much closer to the baseline heterojunction bipolar transistor than a DHBT grown on the InP M-buffer. A high breakdown voltage of 11.3 V was achieved on an M-DHBT with the InAlAs M-buffer. We speculate that the degradation in device characteristics on the InP M-buffer was related to the incomplete dislocation filtering.

Abstract: Mechanical alloying and ball milling are low cost, up-scalable techniques for the preparation of high purity chalcogenide nanopowders to be used as precursor material for printing thin film solar cells. In this study, high purity copper indium selenium (Cu-In-Se) alloy nanopowders with 20-200 nm particle size were synthesized from macroscopic elemental Cu, In and Se powders via mechanical alloying and planetary ball milling. The particle size distribution, morphology, composition, and purity level of the synthesized Cu-In-Se alloy nanopowders were investigated. Thin Cu-In-Se alloy nanopowder ink coatings, deposited on Mo-coated glass substrates by doctor blading, were converted into a CuInSe2 semiconductor film by selenization heat treatment in Se vapor. The CuInSe2 film showed semiconducting band gap around 1 eV measured by photoluminescence spectroscopy. CuInSe2 absorber layer based thin film solar cell devices were fabricated to assess their performance. The solar cell device showed a total efficiency of 4.8%, as measured on 0.25 cm(2) area cell. (c) 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.