Yeadon A.D.,Plasma Quest Ltd |
Yeadon A.D.,University of Surrey |
Wakeham S.J.,Plasma Quest Ltd |
Brown H.L.,Plasma Quest Ltd |
And 4 more authors.
Thin Solid Films | Year: 2011
Indium tin oxide (ITO) thin films with a specific resistivity of 3.5 × 10 - 4 Ω cm and average visible light transmission (VLT) of 90% have been reactively sputtered onto A4 Polyethylene terephthalate (PET), glass and silicon substrates using a remote plasma sputtering system. This system offers independent control of the plasma density and the target power enabling the effect of the plasma on ITO properties to be studied. Characterization of ITO on glass and silicon has shown that increasing the plasma density gives rise to a decrease in the specific resistivity and an increase in the optical band gap of the ITO films. Samples deposited at plasma powers of 1.5 kW, 2.0 kW and 2.5 kW and optimized oxygen flow rates exhibited specific resistivity values of 3.8 × 10 - 4 Ω cm, 3.7 × 10 - 4 Ω cm and 3.5 × 10 - 4 Ω cm and optical gaps of 3.48 eV, 3.51 eV and 3.78 eV respectively. The increase in plasma density also influenced the crystalline texture and the VLT increased from 70 to 95%, indicating that more oxygen is being incorporated into the growing film. It has been shown that the remote plasma sputter technique can be used in an in-line process to produce uniform ITO coatings on PET with specific resistivities of between 3.5 × 10 - 4 and 4.5 × 10 - 4 Ω cm and optical transmission of greater than 85% over substrate widths of up to 30 cm. © 2011 Elsevier B.V. All rights reserved.
Brown H.L.,Plasma Quest Ltd. |
Brown H.L.,University of Surrey |
Thornley S.A.,Plasma Quest Ltd. |
Wakeham S.J.,Plasma Quest Ltd. |
And 3 more authors.
Journal of Physics D: Applied Physics | Year: 2015
With the progression towards higher aspect ratios and finer topographical dimensions in many micro- and nano-systems, it is of technological importance to be able to conformally deposit thin films onto such structures. Sputtering techniques have been developed to provide such conformal coverage through a combination of coating re-sputtering and ionised physical vapour deposition (IPVD), the latter by use of a secondary plasma source or a pulsed high target power (HiPIMS). This paper reports on the use of an alternate remote plasma sputtering technique in which a high density (>1013 cm-3) magnetised plasma is used for sputter deposition, and additionally is shown to provide IPVD and a re-sputtering capability. From the substrate I-V characteristics and optical emission spectroscopy (OES) data, it is shown that remote plasma sputtering is an inherently continuous IPVD process (without the need of a secondary discharge). Through the reactive deposition of Al2O3 onto complex structures, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX) results demonstrate that applying a negative substrate bias during film growth can result in re-sputtering of deposited material and film growth on surfaces obscured from the initial sputter flux. Using 5 : 1 (height : width) aspect ratio trenches, the substrate bias was set to 0,-245 and -334 V. At 0 V substrate bias, the alumina coating is predominantly deposited on the horizontal surfaces; at -344 V, it is predominantly deposited onto the side walls and at -245 V a more uniform layer thickness is obtained over the trench. The process was optimised further by alternating the substrate bias between -222 and -267 V, with a 50% residence time at each voltage, yielding a more uniform conformal coverage of the 5 : 1 aspect ratio structures over large areas. © 2015 IOP Publishing Ltd.
Agency: European Commission | Branch: H2020 | Program: RIA | Phase: SC5-12a-2014 | Award Amount: 6.20M | Year: 2015
The goal of INREP is to develop and deploy valid and robust alternatives to indium (In) based transparent conductive electrode materials as electrodes. In-based materials, mainly ITO, are technologically entrenched in the commercial manufacture of components like LEDs (both organic and inorganic), solar cells, touchscreens, so replacing them with In-free transparent conducting oxides (TCOs) will require holistic approach. The INREP philosophy is to meet this challenge by addressing the whole value chain via an application focused research programme aiming at developing tailor made solutions for each targeted application. This programme will produce a complete evaluation of the relevant properties of the proposed TCOs, including the impact of deposition technique, and by doing so, devise optimum processes for their application in selected, high value application areas. The selected application areas are organic and inorganic light emitting diodes (LEDs), solar cells and touchscreens. The physical properties of interest are the transparency, electrical conductivity, work function, texture, and chemical and thermal stability. To reach its overall goal, INREP brings together industrial and academic experts in TCOs, the technology and processes for their deposition and their applications in a concerted research programme that will result in the creation of TCOs and deposition technologies with the optimum opto-electrical properties suitable for the economic and safe manufacture of the specified photonic or opto-electronic components. The approach will include life cycle assessments of the environmental impact of the developed TCO materials and of their formation technologies over the entire period from application in manufacturing, throughcomponent operation into waste management.
Lu L.,University of Bolton |
Guo M.,University of Bolton |
Thornley S.,Plasma Quest Ltd. |
Han X.,University of Bolton |
And 6 more authors.
Solar Energy Materials and Solar Cells | Year: 2016
Nb-doped TiO2 (TNO) thin films with high electrical conductivity and excellent transparency were fabricated for the first time by reactive remote-plasma sputtering deposition. TNO films were deposited on non-alkali glass slides at room temperature, using a reactive remote plasma sputtering technology, followed by low-temperature annealing in ambient air. The as-deposited films were amorphous which were then crystallised into anatase nanocrystals after a short thermal exposure of 30 min at a moderate temperature of 280 °C. Such low temperature crystallisation induced remarkable enhancement of both conductivity and transparency, with the annealed samples demonstrating low resistivity of 6.4×10-4 Ω cm at room temperature and up to 87% optical transmittance. Fundamentally, the excellent transparent conductivity from the current work is attributed to the interplay between doping Nb to the Ti sub-lattice sites of the anatase phase and energetic/electronic effects due to formation of native defects. The achieved optical transparency and electrical conductivity for TNO are comparable to those for tin-doped indium oxide (ITO), thus demonstrating great potential in low-carbon processing of TNO to substitute the ITO that is based on the depleting and expensive indium resource. © 2016 Elsevier B.V.
Tsakonas C.,Nottingham Trent University |
Wakeham S.,Plasma Quest Ltd. |
Cranton W.M.,Nottingham Trent University |
Cranton W.M.,Sheffield Hallam University |
And 5 more authors.
IEEE Journal of the Electron Devices Society | Year: 2016
Highly transparent thin film electroluminescent structures offering excellent switch on characteristics, high luminance and large break-down voltages have been deposited onto glass and flexible polymeric materials with no substrate heating using high target utilization sputtering. Deposition of ZnS:Mn as the active light emitting layer and Y2O3, Al2O3, Ta2O5, and HfO2 as dielectric materials arranged in single and multiple layer configurations were investigated. Devices incorporating Al2O3, HfO2 quadruple layers demonstrate the highest attainable luminance at low threshold voltage. Single pulse excimer laser irradiation of the phosphor layer prior to deposition of the top dielectric layer enhanced the luminance of the devices. The devices fabricated on glass and polymeric substrates exhibited a maximum luminance of 500 and 450 cdm-2 when driven at 270VRMS and 220VRMS, respectively, with a 1.0 kHz sine wave. © 2013 IEEE.
Vopsaroiu M.,National Physical Laboratory United Kingdom |
Cain M.G.,National Physical Laboratory United Kingdom |
Woolliams P.D.,National Physical Laboratory United Kingdom |
Weaver P.M.,National Physical Laboratory United Kingdom |
And 4 more authors.
Journal of Applied Physics | Year: 2011
The ability to dynamically tune the coercive field of magnetic thin films is a powerful tool for applications, including in magnetic recording disk technologies. Recently, a number of papers have reported the electrical voltage control of the coercive field of various magnetic thin films in multiferroic composites. Theoretically, this is possible in magneto-electric (ME) multiferroics due to the piezoferroelectric component that can be electrically activated to dynamically modify the properties of the magnetic component of the composite via a direct or strain mediated ME coupling. In this paper we fabricated and examined such structures and we determined that the magnetic coercive field reduction is most likely due to a heating effect. We concluded that this effect is probably an artifact that cannot be attributed to a multiferroic coupling. © 2011 American Institute of Physics.
Agency: European Commission | Branch: FP7 | Program: CP-TP | Phase: NMP.2012.4.1-2 | Award Amount: 4.46M | Year: 2012
Waste Electrical and Electronic Equipment is considered to increase drastically in the coming decades. WEEE contains considerable quantities of valuable components used in high-tech applications that currently are not recycled. Europe needs to improve and develop Recovery, Recycling and Reuse of critical materials in order to avoid the dependency on imports, high prices and risk of supply imposed by countries owning mineral reserves. RECYVAL-NANO project will develop an innovative recycling process for recovery and reuse of indium, yttrium and neodymium metals from Flat Panels Displays (FPD), one of the most growing waste sources. The project will be addressed not only to the recovery of these critical elements, but also the recycling process developed will result in the direct extraction of metallorganic precursors for direct reuse in the production of high added value nanoparticles that is ITO, Y2O3:Eu3\ and Nd-Fe-B. The project will develop an integral study of the recycling process, starting with logistic issues of the waste collection, optimising mechanical sorting technologies and developing innovative ones for the recovery and concentration of smaller fractions containing indium, yttrium and neodymium, developing simplified solvent extraction routes based on tailored chemical extraction agents able to extract a 95 % of the key metal in a metallorganic extracted solutions, and using these extracted solutions as precursors in the direct production of advanced nanoparticles. RECYVAL-NANO will validate the recycling process developed through the construction, optimisation and demonstration of full pilot lines for mechanical recycling of FPDs (500 kg/h) and hydrometallurgical metal recovery processes (500 g/h). Finally, the demonstration of the superior performance application of ITO, Y2O3:Eu3\ and Nd-Fe-B nanoparticles in electronic applications of transparent conductors, LEDs and permanent magnets respectively will complete the entire cycle of the project.
Li F.M.,University of Cambridge |
Bayer B.C.,University of Cambridge |
Hofmann S.,University of Cambridge |
Dutson J.D.,Plasma Quest Ltd. |
And 4 more authors.
Applied Physics Letters | Year: 2011
Amorphous hafnium oxide (HfOx) is deposited by sputtering while achieving a very high k∼30. Structural characterization suggests that the high k is a consequence of a previously unreported cubiclike short range order in the amorphous HfOx (cubic k∼30). The films also possess a high electrical resistivity of 1014 cm, a breakdown strength of 3 MV cm-1, and an optical gap of 6.0 eV. Deposition at room temperature and a high deposition rate (∼25 nm min-1) makes these high- k amorphous HfOx films highly advantageous for plastic electronics and high throughput manufacturing. © 2011 American Institute of Physics.
Li F.M.,University of Cambridge |
Waddingham R.,University of Cambridge |
Milne W.I.,University of Cambridge |
Flewitt A.J.,University of Cambridge |
And 4 more authors.
Thin Solid Films | Year: 2011
With the emergence of transparent electronics, there has been considerable advancement in n-type transparent semiconducting oxide (TSO) materials, such as ZnO, InGaZnO, and InSnO. Comparatively, the availability of p-type TSO materials is more scarce and the available materials are less mature. The development of p-type semiconductors is one of the key technologies needed to push transparent electronics and systems to the next frontier, particularly for implementing p-n junctions for solar cells and p-type transistors for complementary logic/circuits applications. Cuprous oxide (Cu2O) is one of the most promising candidates for p-type TSO materials. This paper reports the deposition of Cu2O thin films without substrate heating using a high deposition rate reactive sputtering technique, called high target utilisation sputtering (HiTUS). This technique allows independent control of the remote plasma density and the ion energy, thus providing finer control of the film properties and microstructure as well as reducing film stress. The effect of deposition parameters, including oxygen flow rate, plasma power and target power, on the properties of Cu2O films are reported. It is known from previously published work that the formation of pure Cu2O film is often difficult, due to the more ready formation or co-formation of cupric oxide (CuO). From our investigation, we established two key concurrent criteria needed for attaining Cu2O thin films (as opposed to CuO or mixed phase CuO/Cu2O films). First, the oxygen flow rate must be kept low to avoid over-oxidation of Cu2O to CuO and to ensure a non-oxidised/non-poisoned metallic copper target in the reactive sputtering environment. Secondly, the energy of the sputtered copper species must be kept low as higher reaction energy tends to favour the formation of CuO. The unique design of the HiTUS system enables the provision of a high density of low energy sputtered copper radicals/ions, and when combined with a controlled amount of oxygen, can produce good quality p-type transparent Cu2O films with electrical resistivity ranging from 102 to 104 Ω-cm, hole mobility of 1-10 cm2/V-s, and optical band-gap of 2.0-2.6 eV. These material properties make this low temperature deposited HiTUS Cu 2O film suitable for fabrication of p-type metal oxide thin film transistors. Furthermore, the capability to deposit Cu2O films with low film stress at low temperatures on plastic substrates renders this approach favourable for fabrication of flexible p-n junction solar cells. © 2011 Elsevier B.V. All rights reserved.
Agency: GTR | Branch: Innovate UK | Program: | Phase: Collaborative Research & Development | Award Amount: 430.00K | Year: 2014
Transparent conducting oxides (TCO) are fundamental to various large area devices essential to the modern society (e.g. thin film solar cells, touch screens and flat-panel displays). This project aims at delivering an innovative pilot coating system by scaling up the unique high-target-utilisation-sputtering (HiTUS) coating process invented in the UK to roll-to-roll capacity. This will demonstrate its high-throughput coating potential for TCO production at radically lower consumption of energy and materials. Novel conducting oxides without using depleting indium metal will be formulated using an advanced designer approach, and specifically formulated coatings with remarkable TCO properties will be delivered through process optimisation, thus demonstrating the HiTUS technologys technical readiness for commercialisation and providing a solid foundation for entry to a growing $8bn market resulting from the ever increasing demand for TCO products based particularly on sustainable and environmentally friendly material resources. The coating system from this work can also be used in the fabrication of functional thin films for other advanced application devices.