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The reconstruction of 4°off 4H-SiC surfaces was investigated using Si melting at 1550°C in a SiC/Si/SiC sandwich configuration. Despite systematically obtaining a macrostepped morphology over the entire areas in contact with the liquid Si, the steps were found wavy when using as-received 4H-SiC wafers. The regularity and straightness of the steps were significantly improved when the surface reconstruction was performed on processed surfaces: on re-polished surfaces the steps were found to be regular and straight in some cases, while this was constantly observed on as-grown epitaxial layers. After a reconstruction process of 2h, the best regularity of the steps was obtained with an average width of ̴ 3-5 μm. Increasing the processed area from 1.44 to 4 cm2 did not affect the results which suggests a good scalability of the process.

Current electronics technology increasingly demands higher integration, flexibility, higher efficiency, and performance aspects such as compatibility with higher temperature operation of the semiconductor devices, which may find limitations when silicon is used. The superior intrinsic properties of SiC, eventually combined with the ability of growing monolithically epitaxial, high quality graphene on a SiC wafer (1), makes it a reliable alternative for some electronic applications, such as field effect transistors (FET), radio frequency (RF) power amplifiers, integrated circuits (IC), or sensors. In this work, we describe the fabrication and preliminary electrical characterizations of epitaxial graphene (EG) on a SiC substrate FET devices based on an alternative back gate architecture. We propose a new approach in which the FET device is built on a 4◦ off-axis cut, N+ doped 4H-SiC substrate (the back gate) with, on top of, it a 1μm semi-insulating homoepitaxial layer of SiC compensated with vanadium (the dielectric layer). EG will be used as FET conduction channel. Using this V-compensated dielectric layer is aimed to minimize effects on the FET characteristics such as from defects in the SiC crystal, especially below the FET active areas, which would have occurred when using ion implantation to create a buried gate. The EG film was grown by the high temperature Si sublimation method under an Ar ambient. Raman spectroscopy, Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) were applied in the structural characterization of epigraphene. The lack of D-peak in Raman spectra, together with SEM and AFM images, indicate that high quality monolayer to few layer epitaxial graphene fully covering the SiC surface is deposited. The electrical characteristics of the EG channel-devices and the functionality of the bottom gate were examined with 2-probe and 4-probe method. The electrical properties of the FET devices were also investigated with 3 terminal configuration.

Owing to their low dark current, high transparency, high thermal conductivity, and potential radiation hardness, there is a special interest in silicon carbide (SiC) devices for radiation monitoring in radiation harsh environments and with elevated temperatures and, especially, for the plasma diagnostic systems in future nuclear fusion reactors. In this work, four-quadrant p-n junction diodes produced on epitaxial 4H-SiC substrates are studied. The impact of electron, neutron, and proton irradiations (up to fluences of 1 × 10 16 electrons (e)/cm 2 , 2 × 10 15 neutrons (n)/cm 2 , and 2.5 × 10 15 protons (p)/cm 2 , respectively) on the electrical characteristics is studied by means of current-voltage (I-V) and capacitance-voltage (C-V) techniques. Regardless of the particle type and applied fluences, the results show similar low reverse currents for irradiated SiC devices, which are at least about four orders of magnitude lower than comparable Si devices. The effects of irradiation on interquadrant resistance and charge build-up in the interquadrant isolation are assessed. Furthermore, device performance as a radiation detector is investigated upon exposure to a collimated 239 Pu- 241 Am- 244 Cm trialpha source. The performance at room temperature is preserved even for the highest irradiation fluences, despite the fact that the rectification character in electrical characteristics is lost. From the results, advantages of using SiC devices in alpha particle detection in harsh environments can be envisaged., This work was supported in part by the Spanish Ministry of Science, Innovation and Universities through the Nuclear and Particle Physics Program under Project FIS-FPN-RTI2018-094906-B-C22 (MCIU/FEDER UE), in part by the European Union’s Horizon 2020 Research and Innovation Program under Grant 654168 (AIDA-2020), in part by a collaborative research project at Nuclear Professional School, School of Engineering, The University of Tokyo, under Grant 20016, in part by The Japan Society for the Promotion of Science KAKNHI under Grant JP19K05337, and in part by MINECO through the use of the Spanish ICTS Network MICRONANOFABS. The work of Gemma Rius was supported by the Spanish Ministry of Science and Innovation through Ayudas Ramón y Cajal 2016 under Reference RYC-2016-21412.

Due to their low leakage current, low noise levels, high thermal conductivity, and potential radiation hardness, SiC devices offer various advantages over Si devices in certain applications. As a result, they are being considered for operation in harsh environments, such as plasma diagnostic systems in future nuclear fusion reactors or in high energy physics applications. We report on relevant results of the GRACE project, which seeks to deliver a new generation of SiC sensors with graphene-enhanced contacts. Such devices are aimed to be radiation-hard and functional at high temperatures. The work presented in this paper focuses on the optimisation of the electrical contacts, along with the electrical characterisation and radiation-tolerance assessment of the first sensor prototypes produced., This work was supported by the Spanish State Research Agency (AEI) and the European Regional Development Fund (ERDF), ref. RTC-2017-6369-3.

Magneto-ionics is an emerging field in materials science where voltage is used as an energy-efficient means to tune magnetic properties, such as magnetization, coercive field, or exchange bias, by voltage-driven ion transport. We first discuss the emergence of magneto-ionics in the last decade, its core aspects, and key avenues of research. We also highlight recent progress in materials and approaches made during the past few years. We then focus on the "structural-ion"approach as developed in our research group in which the mobile ions are already present in the target material and discuss its potential advantages and challenges. Particular emphasis is given to the energetic and structural benefits of using nitrogen as the mobile ion, as well as on the unique manner in which ionic motion occurs in CoN and FeN systems. Extensions into patterned systems and textures to generate imprinted magnetic structures are also presented. Finally, we comment on the prospects and future directions of magneto-ionics and its potential for practical realizations in emerging fields, such as neuromorphic computing, magnetic random-access memory, or micro- and nano-electromechanical systems., Financial support by the European Research Council (SPIN-PORICS 2014-Consolidator Grant Agreement No. 648454, and the MAGIC-SWITCH 2019-Proof of Concept Grant, Agreement No. 875018), the Spanish Government (Nos. MAT2017-86357-C3-1-R, PDC2021-121276-C31, and PID2020-116844RB-C21), the Generalitat de Catalunya (2017-SGR-292 and 2018-LLAV-00032), and the European Regional Development Fund (Nos. MAT2017-86357-C3-1-R and 2018-LLAV-00032) were acknowledged. E.M. acknowledges support as a Serra Húnter Fellow. G.R. acknowledges support from Ayudas Ramon y Cajal No. RYC-2016-21412., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Objective. The development of experimental methodology utilizing graphene micro-transistor arrays to facilitate and advance translational research into cortical spreading depression (CSD) in the awake brain. Approach. CSDs were reliably induced in awake nontransgenic mice using optogenetic methods. High-fidelity DC-coupled electrophysiological mapping of propagating CSDs was obtained using flexible arrays of graphene soultion-gated field-effect transistors (gSGFETs). Main results. Viral vectors targetted channelrhopsin expression in neurons of the motor cortex resulting in a transduction volume 1 mm3. 5-10 s of continous blue light stimulation induced CSD that propagated across the cortex at a velocity of 3.0 0.1 mm min-1. Graphene micro-transistor arrays enabled high-density mapping of infraslow activity correlated with neuronal activity suppression across multiple frequency bands during both CSD initiation and propagation. Localized differences in the CSD waveform could be detected and categorized into distinct clusters demonstrating the spatial resolution advantages of DC-coupled recordings. We exploited the reliable and repeatable induction of CSDs using this preparation to perform proof-of-principle pharmacological interrogation studies using NMDA antagonists. MK801 (3 mg kg-1) suppressed CSD induction and propagation, an effect mirrored, albeit transiently, by ketamine (15 mg kg-1), thus demonstrating this models' applicability as a preclinical drug screening platform. Finally, we report that CSDs could be detected through the skull using graphene micro-transistors, highlighting additional advantages and future applications of this technology. Significance. CSD is thought to contribute to the pathophysiology of several neurological diseases. CSD research will benefit from technological advances that permit high density electrophysiological mapping of the CSD waveform and propagation across the cortex. We report an in vivo assay that permits minimally invasive optogenetic induction, combined with multichannel DC-coupled recordings enabled by gSGFETs in the awake brain. Adoption of this technological approach could facilitate and transform preclinical investigations of CSD in disease relevant models., This work has been funded by the European Union's Horizon 2020 research and innovation programme under Grant Agreement Nos. 785219 and 881603 (Graphene Flagship) and co-funded by the European Regional Development Funds (ERDF) allocated to the Programa operatiu FEDER de Catalunya 2014–2020, with the support of the Secretaria d'Universitats i Recerca of the Departament d'Empresa i Coneixement of the Generalitat de Catalunya for emerging technology clusters devoted to the valorization and transfer of research results (GraphCAT 001-P-001702). RW is funded by a Senior Research Fellowship awarded by the Worshipful Company of Pewterers. EMC was awarded an EMBO Short-Term Fellowship ASTF 8157 to spend time in RW's lab. DR is a Biotechnology and Biological Sciences Research Council (BBSRC) LIDo sponsored PhD student. JAG and EDC acknowledge the Ministerio de Ciencia, Innovación y Universidades, la Agencia Estatal de Investigación (AEI) y el Fondo Europeo de Desarrollo Regional (FEDER/UE) for the FIS2017-85787-R research project. This work has made use of the Spanish ICTS Network MICRONANOFABS partially supported by MICINN and the ICTS 'NANBIOSIS', more specifically by the Micro-NanoTechnology Unit of the CIBER in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) at the IMB-CNM. Equipment used was partially funded by Fondo Europeo de Desarrollo Regional (FEDER/UE) FICTS14/20-2-23. IMF is funded by the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 665919.

The past years have witnessed major advancements in all-electrical doping control on cuprates. In the vast majority of cases, the tuning of charge carrier density has been achieved

The past years have witnessed major advancements in all-electrical doping control on cuprates. In the vast majority of cases, the tuning of charge carrier density has been achieved via electric field effect by means of either a ferroelectric polarization or using a dielectric or electrolyte gating. Unfortunately, these approaches are constrained to rather thin superconducting layers and require large electric fields in order to ensure sizable carrier modulations. In this work, we focus on the investigation of oxygen doping in an extended region through current-stimulated oxygen migration in YBa2Cu3O7−δ superconducting bridges. The underlying methodology is rather simple and avoids sophisticated nanofabrication process steps and complex electronics. A patterned multiterminal transport bridge configuration allows us to electrically assess the directional counterflow of oxygen atoms and vacancies. Importantly, the emerging propagating front of current-dependent doping δ is probed in situ by optical microscopy and scanning electron microscopy. The resulting imaging techniques, together with photoinduced conductivity and Raman scattering investigations, reveal an inhomogeneous oxygen vacancy distribution with a controllable propagation speed permitting us to estimate the oxygen diffusivity. These findings provide direct evidence that the microscopic mechanism at play in electrical doping of cuprates involves diffusion of oxygen atoms with the applied current. The resulting fine control of the oxygen content would permit a systematic study of complex phase diagrams and the design of electrically addressable devices., The authors acknowledge the financial support from the Fonds de la Recherche ScientifiqueFNRS, Spanish Ministry of Economy and Competitiveness through the Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015- 0496), SUMATE project (RTI2018-095853-B-C21), cofinanced by the European Regional Development Fund, the COST programme NanoCoHybri (CA 16218), and from the Catalan Government with 2017 SGR 1519. The work of A. Fernańdez-Rodriǵuez has been done in the framework of the doctorate in Materials Science of the Autonomous University of Barcelona (UAB) and is supported by the Spanish Ministry of Economy (BES-2016-077310). The work of A. V. Silhanek is partially supported by the grant CDR J.0151.19 of the F.R.S.- FNRS. S. Blanco Alvarez, S. Melinte, and A. V. Silhanek acknowledge financial support through the grant PDR T.0106.16 of the F.R.S.-FNRS. S. Marinković acknowledges support from F.R.S.-FNRS (Research Fellowship ASP). B. Maiorov was supported by the U.S. DOE, Office of Science, BES, Materials Sciences and Engineering Division. The authors thank the ULiege Microscopy facility CAREM for the SEM investigations. G. Rius acknowledges the Ramon y Cajal grant RYC-2016-21412.

An accurate knowledge of the parameters governing the kinetics of block copolymer self-assembly is crucial to model the time- and temperature-dependent evolution of pattern formation during annealing as well as to predict the most efficient conditions for the formation of defect-free patterns. Here, the self-assembly kinetics of a lamellar PS-b-PMMA block copolymer under both isothermal and non-isothermal annealing conditions are investigated by combining grazing-incidence small-angle X-ray scattering (GISAXS) experiments with a novel modelling methodology that accounts for the annealing history of the block copolymer film before it reaches the isothermal regime. Such a model allows conventional studies in isothermal annealing conditions to be extended to the more realistic case of non-isothermal annealing and prediction of the accuracy in the determination of the relevant parameters, namely the correlation length and the growth exponent, which define the kinetics of the self-assembly., This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 665919, the Spanish Ministry of Economy and Competitiveness (MINECO) under contract Nos. MAT2015-68307-P, MAT2015-66443-C02-1-R, TEC2015-69864-R, RTI2018-102007-B-I00, PID209-107514GB-100, RYC-2016-21412 and the Generalitat de Catalunya under contract No. 2017 SGR 1187. The ICN2 is funded by the CERCA program/Generalitat de Catalunya. The ICN2 is supported by the Severo Ochoa Centres of Excellence programme, funded by the Spanish Research Agency (AEI, grant No. SEV-2017-0706) (MINECO/FEDER, UE).

In this work, we consider a 4H-SiC detector as a plasma diagnostic system for the detection of fusion-born alpha particles in future nuclear fusion reactors. A nuclear microprobe was used to locally irradiate micrometer-sized regions of the detector with 3.5 MeV He ions to fluences from 5 × 109 to 5 × 1011 cm-2. Ion Beam Induced Charge (IBIC) microscopy was employed to study its degradation in Charge Collection Efficiency (CCE) and energy resolution after irradiation. At high reverse-bias voltages, both parameters remain practically unaffected for fluences up to 1 × 1011 cm-2, while a significant deterioration of the spectroscopic performance was observed above 3 × 1011 cm-2. A theoretical drift-diffusion model, in combination with Shockley-Read-Hall recombination statistics, was used to obtain the holes lifetime from the fitting of the experimental CCE values measured at different reverse voltages. Holes lifetime was found to strongly decrease with increasing particle fluence, changing from 57 ns in pristine detectors to 0.2 ns after irradiation with a fluence of 1 × 1011 cm-2., This work was partially funded by the Spanish Ministry of Economy and Competiveness through the Project FIS2015-69362-P (MINECO/FEDER/UE), the Spanish Ministry of Science, Innovation, and Universities through the project RTC-2017-6369-3 (MICINN/FEDER/UE) and the EUROfusion Project CFP-IPH-AWP19-SA-05-CIEMAT-01 (H2020). E. Andrade acknowledges the PASPA-UNAM financial support provided to undertake a sabbatical year and CNA for the invitation to spend his sabbatical in this Institution. G. Rius acknowledges the research grant Nº. RYC-2016-21412.

For over 15 years, the number of studies on graphene electronics has not ceased growing. The rich physics, a set of outstanding properties, and the envisioned range of potential applications have consolidated graphene as a research field in its own. In this Research Update, we address a specific case of graphene for electronics, epitaxial graphene on silicon carbide (SiC) substrates. This paper mainly focuses on the electronic interface of graphene with metals. The first part of this paper describes the most characteristic aspects of the growth of epitaxial graphene on SiC wafers, and the main techniques for graphene material characterization are presented first. The main objective of this paper is to gather and discuss the most representative studies on the graphene–metal interface and the strategies employed to obtain low values for the contact resistances, which is a key feature for achieving the best performance of any graphene electronic devices. To benchmark developments in specifically epitaxial graphene on SiC, we include the results on mechanically exfoliated graphene from HOPG, as well as chemical vapor deposition graphene. In the last part of this paper, relevant device architectures for electrically gating graphene are briefly discussed.

The use of graphene transistors for transducing neural activity has demonstrated the potential to extend the spatiotemporal resolution of electrophysiological methods to lower frequencies, providing a new tool to understand the role of the infra-slow activity.

This paper reviews advanced gate dielectric processes for SiC MOSFETs. The poor quality of the SiO2/SiC interface severely limits the value of the channel field-effect mobility, especially in 4H-SiC MOSFETs. Several strategies have been addressed to overcome this issue. Nitridation methods are effective in increasing the channel mobility and have been adopted by manufacturers for the first generations of commercial power devices. Gate oxide doping techniques have also been successfully implemented to further increase the channel mobility, although device stability is compromised. The use of high-k dielectrics is also analyzed, together with the impact of different crystal orientations on the channel mobility. Finally, the performance of SiC MOSFETs in harsh environments is also reviewed with special emphasis on high temperature operation.

Micro-patterned surfaces with alternate hydrophilic and hydrophobic rectangular areas effectively confine water droplets down to attolitre volumes. The contact angle, volume, and geometry of the confined droplets as a function of the geometry and physico-chemical properties of the confining surfaces have been determined by phenomenological simulations, validated by atomic force microscopy measurements. The combination between experiments and simulations can be used for the purposeful design of arrays with surface-addressable hydrophobicity employed in digital microfluidics and high-throughput screening nanoarrays.

We present the fabrication, operation, and CMOS integration of arrays of suspended silicon nanowires (SiNWs). The functional structures are obtained by a top-down fabrication approach consisting in a resistless process based on focused ion beam irradiation, causing local gallium implantation and silicon amorphization, plus selective silicon etching by tetramethylammonium hydroxide, and a thermal annealing process in a boron rich atmosphere. The last step enables the electrical functionality of the irradiated material. Doubly clamped silicon beams are fabricated by this method. The electrical readout of their mechanical response can be addressed by a frequency down-mixing detection technique thanks to an enhanced piezoresistive transduction mechanism. Three specific aspects are discussed: i) the engineering of mechanically coupled SiNWs, by making use of the nanometer scale overhang that it is inherently-generated with this fabrication process, ii) the statistical distribution of patterned lateral dimensions when fabricating large arrays of identical devices, and iii) the compatibility of the patterning methodology with CMOS circuits. Our results suggest that the application of this method to the integration of large arrays of suspended SiNWs with CMOS circuitry is interesting in view of applications such as advanced radio frequency band pass filters and ultra-high-sensitivity mass sensors., SNM (FP7-ICT-2011-8)) and Nanointegra (TEC2015-69864-R)

Recording infraslow brain signals (, This work was funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 696656 (Graphene Flagship) and no. 732032 (BrainCom). This work has made use of the Spanish ICTS Network MICRONANOFABS partially supported by MINECO and the ICTS ‘NANBIOSIS’, more specifically by the Micro-NanoTechnology Unit of the CIBER in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) at the IMB-CNM. E.M.C. acknowledges that this work has been done in the framework of the PhD in Electrical and Telecommunication Engineering at the Universitat Autònoma de Barcelona. E..C. thanks the Spanish Ministerio de Economía y Competitividad for the Juan de la Cierva postdoctoral grant IJCI-2015–25201. T. Durduran acknowledges support from Fundació CELLEX Barcelona, Ministerio de Economía y Competitividad /FEDER (PHOTODEMENTIA, DPI2015–64358-C2–1-R), the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2015–0522) and the Obra Social “la Caixa” Foundation (LlumMedBcn). M.V.S.V. acknowledges support from MINECO BFU2017-85048-R. ICN2 is supported by the Severo Ochoa programme fromSpanish MINECO (grant no. SEV-2017-0706).

Graphene is a 2D material with potential for almost any purpose, thanks to a combination of excellent characteristics, e.g. high electrical conductivity. Graphene grown on SiC wafers is one of the promising routes for graphene integration into planar technology electronic applications. Synthesis is based on the decomposition of a SiC single crystal surface at high temperature, where Si-terminated SiC substrates require the formation of the C buffer layer. In spite of numerous experimental and theoretical works the understanding and control upon crucial factors such as step and terrace stability or surface roughening is far from been fully comprehended and then technologically optimized. We present experimental results on the deposition of graphene onto Si-terminated 6H-SiC. We analyze the effect of ex situ and in situ conditionings of the SiC surface in the thermal decomposition and reconstruction of the SiC terraces, toward higher control upon the growth process of graphene films.

The main characteristics of focused electron beam induced deposition (FEBID) and focused ion beam induced deposition (FIBID) are presented. FEBID and FIBID are two nanopatterning techniques that allow the fabrication of submicron patterns with nanometer resolution on selected locations of any kind of substrate, even on highly structured supports. The process consists of mask less serial deposition and can be applied to a wide variety of materials, depending strictly on the precursor material source used. The basic mechanism of FEBID and FIBID is the adsorption of volatile precursor molecules onto the sample surface and decomposition of the molecules induced by the energetic electron and ion focused beams. The essential similarities of the two techniques are presented and especial emphasis is dedicated to highlighting their main differences, such as aspects related to resolution, deposition rate, deposits purity, substrate integrity, etc. In both cases, the factors interplay and complex mechanisms are still understood in a qualitative basis, so much work can still be done in terms of modeling and simulating the processes involved in FEBID and FIBID. Current work on FEBID and FIBID is presented through examples of achievements, interesting results and novel approaches.

In this work, the complete technological process for the fabrication of Ti/graphene oxide (GO)/Ti structures is discussed. A microelectronics-compatible deposition technique for GO films is developed, which enables fully covered samples. Control over GO thickness is obtained by a multiple-step spin coating process. GO films have been interfaced for preliminary electrical testing. First insights into the resistive switching properties of Ti/GO/Ti structures and limitations are also presented. Further investigation is needed to determine the potential of GO in the field of flexible non-volatile memories, where optimization of GO films is required.

SiC crystal is a wide band gap material of high hardness and chemical inertness. Graphene is nowadays a ubiquitous 2D material that would revolutionize many applications. Combining the characteristics of SiC and graphene higher performance and efficiency are expected, e.g. for high frequency electronic devices. The obtaining of graphene directly on SiC substrates by a single step thermal decomposition process is promising, but optimal standardized conditions are not established. We present the use of chemical-mechanical polishing (CMP) as a pre-graphene growth SiC conditioning to enable deep comprehension of the mechanisms of SiC decomposition and control towards selective formation of graphene.

© 2016 by Taylor & Francis Group, LLC. Electrochemical capacitors have been developing fast in recent years, and are slowly becoming an increasingly impor tant component in the energy storage mix. Their particular properties, high power density, and medium energy densities, have made them suitable for a growing number of applications such as regenerative breaking and fast charging toys. Owing to its polarizability, electrical conductivity, acces sibility, easy processability, relatively low cost, and chemical stability in a wide range of pH, traditionally, carbon has been the principal component of electrochemical capacitor elec trodes. There are already well-established methods of obtain ing high surface area materials with controlled pore size. Now graphene, with very high surface area and electrical conduc tivity seems a natural candidate material from which to make supercapacitor electrodes. This chapter reviews efforts toward the application of gra phene in its various forms (from exfoliated powder to vertically chemical vapor-grown carbon nanowalls) into supercapacitor electrodes. Starting from a general introduction into the work ing and mechanism of capacitors and the context in which they operate, we review methods of electrode production, cur rent performance, and possible application areas. We end by suggesting routes for further exploration.

Graphical abstractDisplay Omitted Highlights? An accurate method to characterize nanoobject-metal line contacts is presented. ? The contact end resistance test structure is adapted from microelectronics. ? The measurement of an individual nanocontact is allowed. ? Contact resistivity allows prediction of contact resistance for any contact size. This paper presents an accurate method and test structure to evaluate ohmic nanocontacts. The procedure permits the characterization of the contact resistance between standard-in-microtechnology interconnect lines and a certain nanoscaled-in-width object. It is based on the adaption of the classic contact end resistance structure used for the measurement of the contact end resistance in microelectronic technologies. After the theoretical model study, the methodology is validated for the single-walled carbon nanotube case.

(Received 30 January 2012; Accepted 11 April 2012; Published 30 June 2012)We present the phenomenological study of process parameters, characteristics and limitations of carbon nanowalls(CNW) growth by means of microwave plasma enhanced chemical vapor deposition in order to optimize the synthesisof CNW samples for targeted applications, such as supercapacitors or batteries. The growth of CNWs directly ontocommercial Cu foils is simple, resulting in a higher density as compared to SiO

The increased interest to develop novel nanostructured devices, such as those intended for molecular nanoelectronics, requires the development of advanced characterization. We present the properties of carbon nanotube (CNT) atomic force microscopy (AFM) probes for testing multiple properties of nanometer structures, including force spectroscopy. The CNT-AFM probes are made by integrating a high density of MWCNTs in the tip of the probe. In particular, the modulation of the original probe mechanical response due to CNTs in approach-retraction curves is shown, as a consequence of the collective response of the high density of CNTs existing at the tip apex. Illustrative of the potential of the CNT-probe device, the actual determination of physical parameters on HOPG is provided, as a proof of CNT-mediated access to the specific characteristics of the sensed surface. The features observed for the establishment of tip-sample electro-mechanical contact (snap-in and adhesion) reveal the particular interaction forces that are exerted to the CNT tip. The high sensitivity of CNTs to record interaction events comprises both attractive and repulsive mechanisms. Specifically, results suggest the CNT-AFM probe capability to monitor long and short range forces in relation to external electric field and sample charges, capillarity, adhesion and so on. When combined with electrical current monitoring is of extreme precision for conductance determination. [DOI: 10.1380/ejssnt.2012.341]

Continuous monitoring of skin moisture by using a wearable moisture sensor consisting of the materials that have no risk of skin sensitization, such as zinc oxide (ZnO), is essential to optimize the healing process in wound care. Here we tackled the investigation of the optimum electrode for ZnO-based surface acoustic wave (SAW) sensors to achieve this goal. Al and Au electrodes commonly used were compared with a graphene electrode by simulation in terms of the frequency characteristics of the SAW device. Graphene and Al showed the same tendency in frequency characteristics as the 0 thickness electrode (ideal electrode). Since graphene is suitable for flexible devices due to its stretchability and for the long-term stability due to its chemical innerness, it was concluded that graphene is more suitable than the conventional Al and Au electrodes for flexible SAW sensor devices.

The authors present the mechanical and electronic characterization of a novel kind of scanning probe microscopy probe fabricated by the microwave plasma-enhanced chemical vapor deposition growth of carbon nanotubes using a catalytic palladium film deposited only near the apices of commercial tapping mode atomic force microscopy (AFM) cantilevers with the use of a newly developed controlled-area electroplating method. This process is shown to result in the growth of coaxial palladium nanowire/carbon nanotube composite structures (PdNWCNTs). The authors demonstrate that neither the cantilever quality factor nor the cantilever spring constant is significantly degraded by PdNWCNT growth, and show that PdNWCNT probes are adequate for standard tapping mode AFM imaging. Low resistance Ohmic contact between PdNWCNT probes and metal surfaces is demonstrated. Importantly, repeated surface contact and current flow is shown to not damage the PdNWCNTs, indicating that the probes are appropriate for multiprobe conductivity measurements. A brief overview of the fabrication process is also provided.

We present the evaluation of the damage induced on CMOS circuits when exposed to electron- and ion-beams. The experiments are performed by localized exposure of selected areas of the CMOS circuit and surrounding specific sites. Electrical characterization analysis is performed on line, by in situ contacting the circuit during the exposure experiments. The analysis of the experimental results shows up the importance of the localization of the exposure, and mainly of the beam energy of the electrons. From the analysis, optimal exposure conditions are defined to attempt the fabrication of monolithically integrated nanomechanical devices into CMOS circuits (CMOS-NEMS) by electron-beam lithography or ion beam lithography. Examples of these fabrication approaches are shown.

A low resistivity ohmic contact to Si-implanted GaN was achieved using a metal combination of Ti/Al. The effect of a protection cap during post-implantation annealing is investigated, and how it affects the specific contact resistivity ( ρ c ). Relevant differences between the protected (PR) sample with SiO 2 and unprotected (UP) sample during the post-implantation annealing were observed after metal alloying at 700 °C. The lower values of ρ c have been obtained for UP sample, but with very low reproducibility. In contrast, SiO 2 cap layer has demonstrated its relevance in yielding a much more uniformity of a relatively low ρ c around 10 −5 Ω cm 2 . Related mechanism for the uniformity in ρ c was discussed based on the results obtained from electrical measurements, XRD (X-ray diffraction) analysis, AFM (atomic force microscopy) and SEM (scanning electron microscopy) observations.

We report on a recently developed liquid nanodispensing technique (NADIS) using an atomic force microscope probe with an aperture at its apex, to deposit nanodroplets with volumes in the femto- to atto-liter range on a surface. Besides its potential applications in terms of nanopatterning, NADIS is also an efficient tool for studies on wetting at micro to nanometer scale. We illustrate this point by the monitoring of the evaporation of femtoliter sessile droplets using a nanomechanical mass sensor.

We report on the specialised characterization of the local electron beam irradiation of carbon nanotube (CNT) based devices motivated by previous studies on device electrical characteristics. In particular, Kelvin probe force microscopy provides surface potential description of the device under exposure. The experimental characterization is complemented with 3-dimensional electric field modelling of the devices using finite element methods. The modelling includes the effect of electron charging and AFM tip potential. Comparison of simulation and experiments shows good agreement and contributes to assess the distortion of electrical characteristics of CNT based devices under electron beam irradiation.

Control over single wall carbon nanotube structure, positioning and orientation is one of the main challenges for the development of carbon nanotube based electronics. A novel approach consists in placing carbon nanotubes catalyst inside the pores of a zeolite so that control over the nanotube diameter and its growth direction can be achieved. We present the relation between CVD process and carbon nanotube growth when placing the catalyst inside the pores of AlPO4-5 and L type zeolites. By SEM and Raman characterization, we have determined the influence of vacuum pre-treatment and catalyst activation steps. This is the first step towards obtaining batch synthesis of oriented nanotubes at wafer scale.

The behaviour of a new epoxy based resist (mr-EBL 6000.1 XP) as a negative resist for e-beam lithography is presented. We demonstrate that it is possible to define sub-100nm patterns when irradiating thin (120nm) layers of resist with a 10keV electron beam. The dependence of resolution and remaining thickness on electron dose, electron energy and photo acid generator (PAG) content is determined. After the electron beam lithography process, the resist is used as a mask for reactive ion etching. It presents a good etch resistance, that allows transfer of patterns to the substrate with resolution below 100nm.

We study the effect of local charge irradiation on carbon nanotube field effect transistors (CNT-FET), in order to determine the nature of the degradation of the electrical characteristics of CNT-FETs exposed to charged beams, as for example it happens during the fabrication of the device. The study is performed by analyzing the extension of the charge distribution by means of electrical force microscopy (EFM) images, by Monte Carlo simulation of electron trajectories, and by comparing both with the change of the electrical characteristics of the devices after local irradiation with an electron beam under different conditions (beam energy and dose). The CNT-FET device characteristics show a temporary degradation, which depends on the beam energy and irradiated area, and is produced by the charging of the underlying silicon.

Scanning probe techniques such as atomic force microscopy (AFM) or scanning probe lithography are powerful methods for the investigation and modification of surfaces at the nanometer scale. In these techniques, the tip curvature radius and aspect ratio of the probe play a crucial role. Here, we employ carbon nanofiber (CNF) as the tip apex of AFM probes. We show that CNF-AFM probes provide good performance in terms of both resolution and reliability when operating the AFM in dynamic mode. In addition, the CNF apex is responsible for an enhancement of the field-induced chemical reaction in a specific form of scanning probe lithography, local anodic oxidation (LAO), which allows the fabrication of silicon oxide (SiOx) patterns with sub-10 nm resolution. Keywords—carbon nanofiber; atomic force microscope

We report the fabrication of polycrystalline silicon piezoresistive cantilevers with submicron width and thickness for static force measurements, using electron beam lithography (EBL) and silicon micromachining. For cantilevers with length of 150 µm, leg width of 500 nm and thickness of 320 nm, a force sensitivity of 97 µV/pN and a resolution of 30 pN have been obtained. Bigger cantilevers (leg width 6 µm, thickness 650 nm) fabricated with nominally identical processing conditions have shown a lower resistivity and a higher gauge factor. We show that the differences result from an increased effect of the grain boundaries for the smaller cantilevers. But these have a better force sensitivity and resolution due to their reduced lateral dimensions.

Electrodes with novel architectures may enable the construction of high power density batteries with ultrafast charge/discharge performances, which are fundamental for todays power tools, medical devices and transportation systems. Hereby, we demonstrate the application of vertically arranged multilayered-graphene, namely carbon nanowalls (CNW), as a potential high power anode to be used in Li-ion secondary batteries. CNWs are deposited onto Cu foils using microwave plasma enhanced chemical vapor deposition (MPE-CVD) technique. MPE-CVD is a simple and rapid technique, which is effectively proven to produce self-standing layered anodes by single step processing. The direct deposition over Cu avoids the addition of foreign ingredients such as binders and conductive agents. This opens up the possibility to reduce the number of processing steps and processing time, which are key aspects when upscaling is sought. The superior cycling behaviour of the newly elaborated CNWs is demonstrated in lab-scale Li-metal and Li-ion cells (LiFePO4 cathode) capable of very stable and prolonged reversible cycling with excellent durability (>1000 cycles), good specific capacity and capacity retention when subjected to ultrafast current regimes.

© 2015 Society of Photo-Optical Instrumentation Engineers (SPIE). The nanomechanical properties of solvent-cast polymer thin films have been investigated using PeakForce™ Quantitative Nanomechanical Mapping. The samples consisted of films of polystyrene (PS) and poly(methyl methacrylate) (PMMA) obtained after the dewetting of toluene solution on a polymeric brush layer. Additionally, we have probed the mechanical properties of poly(styrene-b-methyl methacrylate) block copolymers (BCP) as randomly oriented thin films. The probed films have a critical thickness, This work was partially funded by the projects SNM (FP7-ICT-2011-8) and FORCE-for-FUTURE (CSD2010-00024).

Micro/nanomechanical resonators have been designed and fabricated with the aim to be used as distributed mass sensors for in situ measurement of the thickness of ultra-thin layers. First, we present a comparative study of three kinds of oscillating devices (cantilever, bridge and quad beam). The quad beam design has been selected for fabrication because it combines high sensitivity and good electrical response. The complete fabrication process of the device is based on electron beam lithography, lift-off and reactive ion etching. The frequency response has been characterized by means of electrical excitation and capacitive read-out.