839 research outputs found
Recommended from our members
Doping stability and opto-electronic performance of chemical vapour deposited graphene on transparent flexible substrates
The primary barrier to wider commercial adoption of graphene lies in reducing the sheet
resistance of the transferred material without compromising its high broad-band optical
transparency, ideally through the use of novel transfer techniques and doping strategies.
Here, chemical vapour deposited graphene was uniformly transferred to polymer supports by
thermal and UV approaches and the time-dependent evolution of the opto-electronic
performance was assessed following exposure to three kinds of common graphene dopants.
Doping with FeCl3 and SnCl2 showed minor, and notably time unstable, enhancement in the
σopt/σdc figure of merit, whilst AuCl3-doping markedly reduced the sheet resistance by 91.5% to 0.29 kΩ/sq for thermally transferred samples and by 34.4% to 0.62 kΩ/sq for UVtransferred samples offering a means to fabricating viable transparent flexible conductors
that near the indium tin oxide benchmarkM. T. Cole thanks the Winston Churchill Trust and the International Young Scientist Research
Fellowship, National Natural Science Foundation of China, for generous financial support.This is the author accepted manuscript. The final version is available at http://digital-library.theiet.org/content/journals/10.1049/iet-cds.2014.0074
Recommended from our members
Analysis of amorphous indium-gallium-zinc-oxide thin-film transistor contact metal using Pilling-Bedworth theory and a variable capacitance diode model
It is widely reported that threshold voltage and on-state current of amorphous indium-gallium-zinc-oxide bottom-gate thin-film transistors are strongly influenced by the choice of source/drain contact metal. Electrical characterisation of thin-film transistors indicates that the electrical properties depend on the type and thickness of the metal(s) used. Electron transport mechanisms and possibilities for control of the defect state density are discussed. Pilling-Bedworth theory for metal oxidation explains the interaction between contact metal and amorphous indium-gallium-zinc-oxide, which leads to significant trap formation. Charge trapping within these states leads to variable capacitance diode-like behavior and is shown to explain the thin-film transistor operation.This work was supported by the Engineering and Physical Sciences Research CouncilThis is the author's accepted manuscript of the publication: http://dx.doi.org/10.1063/1.480199
A philosophical context for methods to estimate origin-destination trip matrices using link counts.
This paper creates a philosophical structure for classifying methods which estimate origin-destination matrices using link counts. It is claimed that the motivation for doing so is to help real-life transport planners use matrix estimation methods effectively, especially in terms of trading-off observational data with prior subjective input (typically referred to as 'professional judgement'). The paper lists a number of applications that require such methods, differentiating between relatively simple and highly complex applications. It is argued that a sound philosophical perspective is particularly important for estimating trip matrices in the latter type of application. As a result of this argument, a classification structure is built up through using concepts of realism, subjectivity, empiricism and rationalism. Emphasis is put on the fact that, in typical transport planning applications, none of these concepts is useful in its extreme form. The structure is then used to make a review of methods for estimating trip matrices using link counts, covering material published over the past 30 years. The paper concludes by making recommendations, both philosophical and methodological, concerning both practical applications and further research
Optimisation of amorphous zinc tin oxide thin film transistors by remote-plasma reactive sputtering
The influence of the stoichiometry of amorphous zinc tin oxide (a-ZTO) thin films used as the semiconducting channel in thin film transistors (TFTs) is investigated. A-ZTO has been deposited using remote-plasma reactive sputtering from zinc:tin metal alloy targets with 10%, 33%, and 50% Sn at. %. Optimisations of thin films are performed by varying the oxygen flow, which is used as the reactive gas. The structural, optical, and electrical properties are investigated for the optimised films, which, after a post-deposition annealing at 500 °C in air, are also incorporated as the channel layer in TFTs. The optical band gap of a-ZTO films slightly increases from 3.5 to 3.8 eV with increasing tin content, with an average transmission ∼90% in the visible range. The surface roughness and crystallographic properties of the films are very similar before and after annealing. An a-ZTO TFT produced from the 10% Sn target shows a threshold voltage of 8 V, a switching ratio of 10, a sub-threshold slope of 0.55 V dec, and a field effect mobility of 15 cm V s, which is a sharp increase from 0.8 cm V s obtained in a reference ZnO TFT. For TFTs produced from the 33% Sn target, the mobility is further increased to 21 cm V s, but the sub-threshold slope is slightly deteriorated to 0.65 V dec. For TFTs produced from the 50% Sn target, the devices can no longer be switched off (i.e., there is no channel depletion). The effect of tin content on the TFT electrical performance is explained in the light of preferential sputtering encountered in reactive sputtering, which resulted in films sputtered from 10% and 33% Sn to be stoichiometrically close to the common ZnSnO and ZnSnO phases.Engineering and Physical Sciences Research Council (Grant ID: EP/M013650/1
Ultra-broadband Polarisers Based on Metastable Free-Standing Aligned Carbon Nanotube Membranes
A carbon nanotube free-standing linearly dichroic polariser is developed using solid-state extrusion. Membrane cohesion is experimentally and numerically demonstrated to derive from inter-tube van der Waals interactions in this family of planar metastable morphologies, controlled by the chemical vapour deposition conditions. Ultra-broadband polarisation (400 nm – 2.5 mm) is shown and corroborated by effective medium and full numerical simulations.This work was supported by the Isaac Newton Trust, Trinity College Cambridge University. M. T. Cole thanks the Winston Churchill Memorial Trust and the Oppenheimer Research
Fellowship, Cambridge University, for generous financial support.This is the author accepted manuscript. The final version is available from Wiley at http://onlinelibrary.wiley.com/doi/10.1002/adom.201400238/abstract
Atomic Layer Deposition of ZnO on Multi-walled Carbon Nanotubes and Its Use for Synthesis of CNT-ZnO Heterostructures.
In this article, direct coating of ZnO on PECVD-grown multi-walled carbon nanotubes (MWCNTs) is achieved using atomic layer deposition (ALD). Transmission electron microscopy investigation shows that the deposited ZnO shell is continuous and uniform, in contrast to the previously reported particle morphology. The ZnO layer has a good crystalline quality as indicated by Raman and photoluminescence (PL) measurements. We also show that such ZnO layer can be used as seed layer for subsequent hydrothermal growth of ZnO nanorods, resulting in branched CNT-inorganic hybrid nanostructures. Potentially, this method can also apply to the fabrication of ZnO-based hybrid nanostructures on other carbon nanomaterials.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
Recommended from our members
Theoretical Research on a Multibeam-Modulated Electron Gun Based on Carbon Nanotube Cold Cathodes
Multi-beam modulation in a carbon nanotube (CNT) cold cathode electron gun is herein investigated in order to develop miniaturized and fully integrated vacuum electron devices. By exposing the electron source to a millimeter-wave signal, the steady-state field emission current density is efficiently modulated by the incident high-frequency (HF) electric field. Our simulation results of this multi-beam electron gun show that the field emission current density can be efficiently modulated by different incident frequency millimeter waves. We find that the modulation depth is increased by enhancing the HF input power and anode operation voltage. The modulation frequency and phase of each electron beam can be controlled using a single millimeter-wave source and by simply adjusting the lateral distance between adjacent CNT cold cathodes.This work was supported in part by the National Basic Research Program of China under Grant 2013CB933603 and in part by the National Natural Science Foundation of China under Grant U1134006 and Grant 6110104.This is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1109/TED.2016.256558
Bulk molybdenum field emitters by inductively coupled plasma etching.
In this work we report on the fabrication of inductively coupled plasma (ICP) etched, diode-type, bulk molybdenum field emitter arrays. Emitter etching conditions as a function of etch mask geometry and process conditions were systematically investigated. For optimized uniformity, aspect ratios of >10 were achieved, with 25.5 nm-radius tips realised for masks consisting of aperture arrays some 4.45 μm in diameter and whose field electron emission performance has been herein assessed
- …