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The need for higher sensitivity and parallel detection of multiple biological targets drives the research on electronic biosensing platforms based on two-dimensional (2D) materials. However, signal fidelity from individual sensors may be compromised due to the existing nonidealities of 2D electronic devices. Here, we use graphene field effect transistors (gFETs) as a model system to investigate a multisensor device architecture. We identify two potential sources of crosstalk interference between sensors in such a platform: resistive interference through shared gFET channels and capacitive coupling through the shared device substrate. Having illustrated these sources of interference, we offer solutions to mitigate them for ensuring the fidelity of the biosensor signal. This study provides important practical insights for researchers working on 2D biosensor platforms. [ABSTRACT FROM AUTHOR]

The development of a scalable and cost-effective nanofabrication method is of key importance for future advances in nanoelectronics. Thermal scanning probe lithography (t-SPL) is a growing nanopatterning method with potential for parallelization, offering unique capabilities that make it an attractive candidate for industrial nanomanufacturing. Here, we demonstrate the possibility to apply t-SPL for the fabrication of graphene devices. In particular, we use t-SPL to produce high performing graphene-based field effect transistors (FETs). The here described t-SPL process includes the fabrication of high-quality metal contacts, as well as patterning and etching of graphene to define the active region of the device. The electrical measurements on the t-SPL fabricated FETs indicate a symmetric conductance at the Dirac point and a low specific contact resistance without the use of any contact engineering strategy. The entire t-SPL nanofabrication process is performed without the need for masks, and in ambient conditions. Furthermore, thanks to the t-SPL in situ simultaneous patterning and imaging capability, no markers are required. These features substantially decrease fabrication time and cost. [ABSTRACT FROM AUTHOR]

Measurements of the effect of long duration UV irradiation (up to 2905 min) of flight quality diamondlike carbon charge state conversion surfaces for application in space research in the presence of a hydrocarbon atmosphere were done. An isopropanol atmosphere was used for simulating the hydrocarbon gaseous environment for an instrument on a satellite in space. Charge state conversion surfaces are used in neutral particle sensing instruments where neutral atoms have to be ionized prior to the analysis. A narrow-band (126±5 nm) discharge lamp and a broad-band deuterium lamp (112-370 nm) were used as sources of UV radiation. The UV irradiation of a surface results in the desorption of some volatiles present on the surface and the decomposition of others. Desorption of volatiles, mostly water, is observed for both UV sources. The decomposition of the hydrocarbons and the subsequent build-up of a hydrocarbonaceous layer is only observed for the broad-band UV lamp, which is more representative for the space environment. Unfortunately, the hydrocarbonaceous layer cannot be removed thermally, i.e., it is permanent, and causes a degradation of the performance of the charge state conversion surfaces. With the present measurements we can quantify the UV influence at which the degradation of the conversion surfaces becomes noticeable. [ABSTRACT FROM AUTHOR]

The effect of tip radius on atomic force microscopy (AFM) nanoindentation is investigated through indentation on the (111) face of a gold single crystal. The hardness is derived using two different methods: by measuring directly the projected area of the residual indent with AFM images and by measuring the cross-sectional area of the indenter before and after each nanoindentation test. The hardness values obtained from the cross-sectional area of the indenter are comparable with those obtained from images of the residual indent scanned with a sharp tip. Two AFM tips of average radii of 70±12 and 112±26 nm are used to indent the sample to various depths ranging from 4 to 50 nm. For depths above 30 nm, hardness values remain constant around 500 MPa for both indenters. For depths below 30 nm, the hardness increases as the indent depth decreases for the sharp and blunt indenters, and the indent depth dependence is observed over a wider depth range for the sharp indenter. For depths below 30 nm, the hardness values obtained with the sharp indenter are also consistently higher than those obtained with the blunt indenter. The results confirm a size scale effect during nanometer scale indentation for both varying penetration depth and tip radius, both of which influence the volume of material sampled during deformation. [ABSTRACT FROM AUTHOR]

Studies the composition, structure and growth parameters of amorphous diamond-like carbon and carbon nitride (CN[sub x]) films deposited by pulsed laser deposition in vacuum and in nitrogen atmosphere. Core level x-ray photoelectron spectroscopy; Electron energy loss spectroscopy; Micro-Raman spectroscopy.

Studies the nature of the shear-force interaction routinely used in scanning near-field optical microscope. Use of the heterodyne phase-controlled oscillator method to monitor the resonance frequency and quality factor of the tip oscillations; Investigation of the optical and nonoptical detection of the schemes of the shear force.

Stabilizing and manipulating topological magnetic quasiparticles in thin films is of great interest for potential applications in data storage and information processing. Here, we present a strategy for stabilizing magnetic vortices and Bloch lines with controlled position, vorticity, and chirality in a continuous exchange bias system. By tailoring vectorially the unidirectional anisotropy of the system at the nanoscale, via thermally assisted magnetic scanning probe lithography, we show experimentally and via micromagnetic simulations the non-volatile creation of vortex-antivortex pairs. In addition, we demonstrate the deterministic stabilization of cross and circular Bloch lines within patterned Néel magnetic domain walls. This work enables the implementation of complex functionalities based on the control of tailored topological spin-textures in spintronic and magnonic nanodevices. [ABSTRACT FROM AUTHOR]

Magnonics is envisioned to enable highly efficient data transport and processing, by exploiting propagating perturbations in the spin-texture of magnetic materials. Despite the demonstrations of a plethora of proof-of-principle devices, the efficient excitation, transport and manipulation of spin-waves at the nanoscale is still an open challenge. Recently, we demonstrated that the spin-wave excitation and propagation can be controlled by nanopatterning reconfigurable spin-textures in a continuous exchange biased ferromagnetic film. Here, we show that by patterning 90° stripe-shaped magnetic domains, we spatially modulate the spin-wave excitation in a continuous film, and that by applying an external magnetic field we can reversibly "switch-off" the spin-wave excitation. This opens the way to the use of nanopatterned spin-textures, such as domains and domain walls, for exciting and manipulating magnons in reconfigurable nanocircuits. [ABSTRACT FROM AUTHOR]

High-speed detector systems with high dynamic range and pulse width characteristics in the subnanosecond regime are mandatory for high resolution and highly sensitive time-of-flight mass spectrometers. Typically, for a reasonable detector area, an impedance-matched anode design is necessary to transmit the registered signal fast and distortion-free from the anode to the signal acquisition system. In this report, a high-speed microstrip multi-anode multichannel plate detector is presented and discussed. The anode consists of four separate active concentric anode segments allowing a simultaneous readout of signal with a dynamic range of about eight orders of magnitude. The impedance matched anode segments show pulse width of about 250 ps, measured at full width at half maximum, and rise time of ~170 ps, measured with an oscilloscope with a sampling rate of 20 GS/s and 4 GHz analogue bandwidth. The usage of multichannel plates as signal amplifier allowed the design of a lightweight, low power consuming, and compact detector system, suitable, e.g., for the integration into space instrumentation or portable systems where size, weight, and power consumption are limited parameters. [ABSTRACT FROM AUTHOR]

We present an Atomic Force Microscopy (AFM) based method to investigate the rheological properties of liquids confined within a nanosize gap formed by an AFM tip apex and a solid substrate. In this method, a conventional AFM cantilever is sheared parallel to a substrate surface by means of a lock-in amplifier while it is approaching and retracting from the substrate in liquid. The normal solvation forces and lateral viscoelastic shear forces experienced by the AFM tip in liquid can be simultaneously measured as a function of the tip-substrate distance with sub-nanometer vertical resolution. A new calibration method is applied to compensate for the linear drift of the piezo transducer and substrate system, leading to a more precise determination of the tip-substrate distance. By monitoring the phase lag between the driving signal and the cantilever response in liquid, the frequency dependent viscoelastic properties of the confined liquid can also be derived. Finally, we discuss the results obtained with this technique from different liquid-solid interfaces. Namely, octamethylcy-clotetrasiloxane and water on mica and highly oriented pyrolytic graphite. [ABSTRACT FROM AUTHOR]

This is a comprehensive review of the combination of scanning probe microscopy (SPM) with various optical spectroscopies, with a particular focus on Raman spectroscopy. Efforts to combine SPM with optical spectroscopy will be described, and the technical difficulties encountered will be examined. These efforts have so far focused mainly on the development of tip-enhanced Raman spectroscopy, a powerful technique to detect and image chemical signatures with single molecule sensitivity, which will be reviewed. Beyond tip-enhanced Raman spectroscopy and/or topography measurements, combinations of SPM with optical spectroscopy have a great potential in the characterization of structure and quantitative measurements of physical properties, such as mechanical, optical, or electrical properties, in delicate biological samples and nanomaterials. The different approaches to improve the spatial resolution, the chemical sensitivity, and the accuracy of physical properties measurements will be discussed. Applications of such combinations for the characterization of structure, defects, and physical properties in biology and materials science will be reviewed. Due to the versatility of SPM probes for the manipulation and characterization of small and/or delicate samples, this review will mainly focus on the apertureless techniques based on SPM probes. [ABSTRACT FROM AUTHOR]

We report the use of thermochemical nanolithography to convert a precursor polymer film to poly(p-phenylene vinylene) with sub-100 nm spatial resolution, in ambient conditions. The local thermochemical conversion is verified by Raman spectroscopy, fluorescence imaging, and atomic force microscopy. This convenient direct writing of conjugated polymer nanostructures could be desirable for the design and fabrication of future nanoelectronic, nanophotonic, and biosensing devices. [ABSTRACT FROM AUTHOR]

We present a method, polarized Raman (PR) spectroscopy combined with atomic force microscopy (AFM), to characterize in situ and nondestructively the structure and the physical properties of individual nanostructures. PR-AFM applied to individual ZnO nanobelts reveals the interplay between growth direction, point defects, morphology, and mechanical properties of these nanostructures. In particular, we find that the presence of point defects can decrease the elastic modulus of the nanobelts by one order of magnitude. More generally, PR-AFM can be extended to different types of nanostructures, which can be in as-fabricated devices. [ABSTRACT FROM AUTHOR]

The wettability of a thin polymer film was modified twice by thermochemical nanolithography. By means of a first local chemical modification induced by an atomic force microscope tip heated to 110±20 °C, hydrophilic patterns are written over an originally hydrophobic polymer surface. By further heating to 190±20 °C, a second chemical modification reverses the local wettability change introduced by the first chemical modification. This write-read-overwrite capability can be particularly useful in the design of complex nanofluidic devices. [ABSTRACT FROM AUTHOR]

We study nanoscopic friction forces between an atomic force microscope tip and a glass sample. We show how and why it is possible to tune friction forces in a predictable way by changing either the sample temperature, or the humidity in the experimental chamber. We relate the friction behavior to confined water phase transitions. We find that the water gas-liquid phase diagram is the same at the macroscopic scale as at the nanoscopic tip-sample contact. [ABSTRACT FROM AUTHOR]

We present an atomic force microscope study of nanoscopic sliding friction on diamond, diamond-like carbon, and on three CrN thin films with varying hardness obtained by different growth temperatures. For the CrN films, we show that the changes in the friction coefficient can be traced back to variations of the Young modulus. More generally, we show for all samples investigated and in wearless regime, that the nanoscopic friction coefficient is directly linked to the Young modulus. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Studies intersubband relaxation time for InGaAs/AlAs quantum wells with large transition energy. Differential transmission decays; Intersubband transitions in optoelectronic devices.

We report on the measurement of the radial modulus of boron nitride nanotubes (BN-NTs) with various sizes and thicknesses. These BN-NTs are radially much stiffer than previously reported thinner and smaller BN-NTs. Here, we show the key role of the morphology of the nanotubes in determining their radial rigidity; in particular, we find that the external and internal radii, Rext and Rint, have a stronger influence on the radial modulus than the nanotube's thickness. The radial modulus decreases nonlinearly with 1/Rext until reaching, for a large number of layers and a large radius, the transverse elastic modulus of bulk h-BN. [ABSTRACT FROM AUTHOR]