António Marques

Bio: António Marques is an academic researcher from Spanish National Research Council. The author has contributed to research in topics: Transparent conducting film & Thin film. The author has an hindex of 4, co-authored 18 publications receiving 1521 citations. Previous affiliations of António Marques include Universidade Nova de Lisboa.

Wide-bandgap high-mobility ZnO thin-film transistors produced at room temperature

Abstract: We report high-performance ZnO thin-film transistor (ZnO-TFT) fabricated by rf magnetron sputtering at room temperature with a bottom gate configuration. The ZnO-TFT operates in the enhancement mode with a threshold voltage of 19V, a saturation mobility of 27cm2∕Vs, a gate voltage swing of 1.39V∕decade and an on/off ratio of 3×105. The ZnO-TFT presents an average optical transmission (including the glass substrate) of 80% in the visible part of the spectrum. The combination of transparency, high mobility, and room-temperature processing makes the ZnO-TFT a very promising low-cost optoelectronic device for the next generation of invisible and flexible electronics.

Multifunctional Thin Film Zinc Oxide Semiconductors: Application to Electronic Devices

Abstract: In this paper we report some of the recent advances in transparent thin film oxide semiconductors, specifically zinc oxide (ZnO), produced by rf magnetron sputtering at room temperature with multifunctional properties. By controlling the deposition parameters it is possible to produce undoped material with electronic semiconductor properties or by doping it to get either n-type or p-type semiconductor behavior. In this work we refer our experience in producing n-type doping ZnO as transparent electrode to be used in optoelectronic applications such as solar cells and position sensitive detectors while the undoped ZnO can be used as UV photodetector or ozone gas sensor or even as active layer of fully transparent thin film transistors.

Wittgenstein on forms of life and the nature of experience

Abstract: Contents: Nuno Venturinha: Introduction - Barry Stocker: Dialectic of Paradox in the Tractatus: Wittgenstein and Kierkegaard - Maria Filomena Molder: Cries, False Substitutes and Expressions in Image - Jean-Pierre Cometti: Aesthetic Experience and Forms of Life - Stefan Majetschak: Forms and Patterns of Life: A Reassessment of a So-Called Basic Concept in the Late Philosophy of Wittgenstein - James M. Thompson: Translating Form(s)-of-Life? Remarks on Cultural Difference and Alterity - Jesus Padilla Galvez: Form of Life as Arithmetical Experiment - Joachim Schulte: Does the Devil in Hell Have a Form of Life? - Antonio Marques: Forms of Life: Between the Given and the Thought Experiment - Andrew Lugg: Wittgenstein on Reddish Green: Logic and Experience.

ZnO:Ga Thin Films Produced by RF Sputtering at Room Temperature: Effect of the Power Density

Abstract: Ga-doped polycrystalline zinc oxide (GZO) thin films have been deposited at high growth rates by rf magnetron sputtering. The dependence of electrical, optical and morphological properties on the rf power density were investigated. The lowest resistivity of 1.9×10 cm was obtained for a rf power density of 9 W/cm and an argon sputtering pressure of 0.15 Pa at room temperature. The films are polycrystalline with a hexagonal structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface. The films present an overall transmittance in the visible spectra of about 85%. The low resistivity, accomplished with a high growth rate deposited at room temperature, enables the deposition of these films onto polymeric substrates for flexible optoelectronic devices and displays. Introduction Transparent conducting oxides (TCO) with optical transmission more than 80 % in the visible region (550 nm) and resistivity less than 10 cm have been widely used as electrodes for optoelectronic devices [1] and solar cells [2]. Most of the previous research on TCOs has been focused on indium tin oxide (ITO) and fluorine tin oxide (FTO). However, TCO films based on zinc oxide are taking a great impact because of the advantages of low cost, resource availability (about a factor of 1000 more abundant than indium), non-toxicity and high thermal/chemical stability [3]. Non-doped zinc oxide usually presents a high resistivity due to a low carrier concentration. Al, In and Ga have been reported as an effective dopant for zinc oxide based films. Most of the works related to zinc oxide use aluminium as dopant. Nevertheless, aluminium presents a very high reactivity leading to oxidation during the growth of the film, which may become a problem [4]. Galium is less reactive and more resistant to oxidation compared to aluminium. On the other hand, the covalent bond lengths of Ga-O and Zn-O are estimated to be 1.92 and 1.97 Å, respectively. The slightly smaller bond length of Ga-O than that of Zn-O is an advantage since it allows to minimize the deformation of the ZnO lattice even in the case of high gallium concentrations. These were the main reasons why gallium was chosen as dopant. Several methods have also been used like, metal organic chemical vapour deposition, evaporation, magnetron sputtering, sol gel, plasma assisted molecular beam epitaxy, among others [5]. However, most of these techniques need to use moderate temperatures, to obtain low values of resistivity. In addition to the several advantages presented by rf magnetron sputtering, it is also possible to produce highly conductive and transparent GZO without heating the substrate, since additional energy is delivered from the plasma to the growing film – a characteristic of a plasma assisted process. In this paper the electrical, structural and optical properties of GZO were analysed in detail and the effects of the rf power density on the deposition process were investigated. Materials Science Forum Online: 2004-05-15 ISSN: 1662-9752, Vols. 455-456, pp 12-15 doi:10.4028/www.scientific.net/MSF.455-456.12 © 2004 Trans Tech Publications Ltd, Switzerland All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications Ltd, www.scientific.net. (Semanticscholar.org-11/03/20,15:41:06) Title of Publication (to be inserted by the publisher) 13 Experimental Details The GZO films were deposited onto soda lime glass substrates by rf (13.56 MHz) magnetron sputtering using a ceramic oxide target ZnO/Ga2O3 (98:2 wt%) from Super Conductor Materials, Inc. with a purity of 99.99%. The sputtering was carried out under room temperature and the rf power density was varied from 5 to 9 W/cm. The distance between the substrate and the target was 10 cm and the argon flow rate and sputtering pressure were maintained constant at 20 sccm and 0.15 Pa, respectively, for all depositions. The film thickness (800 nm in average for all the samples) was measured using a surface profilometer (Dektak 3D from Sloan Tech.). The electrical resistivity ( ), free carrier concentration (n) and Hall mobility (μH) were inferred by the four point probe method and Hall effect measurements using the van der Pauw geometry (Biorad HL5500) at a constant magnetic field of 0.5 T. X-ray diffraction measurements were performed using Cu-K radiation (Rigaku DMAX III-C diffractometer). The optical transmittance was measured using a UV-VISNIR double beam spectrophotometer (UV-3100 PC, Shimadzu) in the wavelength range from 300 nm to 2500 nm. Results and Discussion 5 6 7 8 9 100 150 200 250 300 D ep os it io n ra te ( Å /m in ) rf power density (W/cm 2 ) Fig. 1. Dependence of growth rate on the rf power density. The films were deposited at room temperature and with a pressure of 0.15 Pa. Fig. 1 shows the dependence of the growth rate (R) on the rf power density (P). It is observed a linear increase on R as the rf power density increases, due to the amount on the number of sputtered particles [6]. A maximum R (280 Å/min) was obtained for a rf power density of 9 W/cm. Deposition rate efficiency (RE) was defined as the slope of the linear deposition rate versus power density [7]: RE = R (Å/min)/P (W/cm ) (1) RE is a useful concept for optimising deposition conditions, magnet arrangements, source-substrate spacing, etc. From the slope of Fig. 1 a RE of 35 Åcm /Wmin was obtained. The low value obtained, is similar to that ones obtained for ceramic targets, mainly due to the lower sputtering yield for this type of materials [8, 9].The dependence of the electrical properties ( , n and μH) of the GZO films as a function of the rf power density is shown in Fig. 2. The lowest electrical resistivity was obtained for a P = 9 W/cm which corresponds to a maximum of the carrier concentration (2.9×10 cm). Another remarkable point observed in these films produced at room temperature, is the lowest values registered on GZO films (typically requiring high temperature), close to the theoretical physical limits [2], which are values in the range of 4×10 cm. These values are only explained by a high efficiency of the gallium dopant atoms, without significant defects ascribed to the grain boundaries and so, no significant barrier effect exists limiting the carrier’s transport between grains. Fig. 3a) shows a typical XRD pattern obtained for a sample prepared with an rf power density of 9 W/cm. It can be clearly seen that the only peak that is present is the {002}, showing that there is a very strong preferential orientation of these crystallographic planes parallel to the substrate. A set of programs for X-ray diffraction peak profile analysis, using different methods, has been previously implemented and tested for the study of a quenched tool steel [10]. In the present paper, Materials Science Forum Vols. 455-456 13

Knowledge, language and mind : Wittgenstein's thought in progress

Abstract: Wittgenstein's Philosophical Investigations is arguably one of the most influential books of the 20th century. It threw a new light on the workings of language and mind, contributing significantly to the understanding of human knowledge. Featuring essays by internationally renowned scholars, this book explores the development of Wittgenstein's ideas in the direction of the Investigations. It offers a comprehensive view of some of the most disputable issues in the study of Wittgenstein's masterpiece and reassesses its relevance within contemporary philosophical debate.

Oxide Semiconductor Thin‐Film Transistors: A Review of Recent Advances

Abstract: Transparent electronics is today one of the most advanced topics for a wide range of device applications. The key components are wide bandgap semiconductors, where oxides of different origins play an important role, not only as passive component but also as active component, similar to what is observed in conventional semiconductors like silicon. Transparent electronics has gained special attention during the last few years and is today established as one of the most promising technologies for leading the next generation of flat panel display due to its excellent electronic performance. In this paper the recent progress in n- and p-type oxide based thin-film transistors (TFT) is reviewed, with special emphasis on solution-processed and p-type, and the major milestones already achieved with this emerging and very promising technology are summarizeed. After a short introduction where the main advantages of these semiconductors are presented, as well as the industry expectations, the beautiful history of TFTs is revisited, including the main landmarks in the last 80 years, finishing by referring to some papers that have played an important role in shaping transparent electronics. Then, an overview is presented of state of the art n-type TFTs processed by physical vapour deposition methods, and finally one of the most exciting, promising, and low cost but powerful technologies is discussed: solution-processed oxide TFTs. Moreover, a more detailed focus analysis will be given concerning p-type oxide TFTs, mainly centred on two of the most promising semiconductor candidates: copper oxide and tin oxide. The most recent data related to the production of complementary metal oxide semiconductor (CMOS) devices based on n- and p-type oxide TFT is also be presented. The last topic of this review is devoted to some emerging applications, finalizing with the main conclusions. Related work that originated at CENIMAT|I3N during the last six years is included in more detail, which has led to the fabrication of high performance n- and p-type oxide transistors as well as the fabrication of CMOS devices with and on paper.

Semiconductor device, and manufacturing method thereof

Abstract: An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Field-effect transistor

Abstract: Provided is a field-effect transistor including an active layer and a gate insulating film, wherein the active layer includes an amorphous oxide layer containing an amorphous region and a crystalline region, and the crystalline region is in the vicinity of or in contact with an interface between the amorphous oxide layer and the gate insulating film

Semiconductor device and display device

Abstract: An object of the present invention is to decrease the resistance of a power supply line, to suppress a voltage drop in the power supply line, and to prevent defective display. A connection terminal portion includes a plurality of connection terminals. The plurality of connection terminals is provided with a plurality of connection pads which is part of the connection terminal. The plurality of connection pads includes a first connection pad and a second connection pad having a line width different from that of the first connection pad. Pitches between the plurality of connection pads are equal to each other.

Lab-on-Skin: A Review of Flexible and Stretchable Electronics for Wearable Health Monitoring

Abstract: Skin is the largest organ of the human body, and it offers a diagnostic interface rich with vital biological signals from the inner organs, blood vessels, muscles, and dermis/epidermis. Soft, flexible, and stretchable electronic devices provide a novel platform to interface with soft tissues for robotic feedback and control, regenerative medicine, and continuous health monitoring. Here, we introduce the term “lab-on-skin” to describe a set of electronic devices that have physical properties, such as thickness, thermal mass, elastic modulus, and water-vapor permeability, which resemble those of the skin. These devices can conformally laminate on the epidermis to mitigate motion artifacts and mismatches in mechanical properties created by conventional, rigid electronics while simultaneously providing accurate, non-invasive, long-term, and continuous health monitoring. Recent progress in the design and fabrication of soft sensors with more advanced capabilities and enhanced reliability suggest an impending t...