1,720,991 research outputs found
Pseudo spin-valves with Al or Nb as spacer layer: GMR and search for spin switch behaviour
No full textFocus on graphene and related materials
No full textThis focus collection, dedicated to graphene and other 2D materials, summarizes
some of the contributions presented at the International Conference GM-
2016 ‘Graphene and related materials: properties and applications’ held in Paestum,
Italy, in May 2016. It was an intense multidisciplinary meeting that brought together
about 150 physicists, chemists and engineers working on fundamental and applicative
aspects
SWCNT-Si Photodetector with Voltage-Dependent Active Surface
No full textNew works on Carbon Nanotubes-Silicon MIS heterostructures showed that the presence of thickness inhomogeneities in the insulating layer across the device can be exploited to increase its functionalities. In this work, we report the fabrication and the characterization of a device consisting of a Single-Walled Carbon Nanotube (SWCNT) film onto an n-type silicon substrate where the nitride interlayer between the nanotubes
and the silicon has been intentionally etched to obtain different thicknesses. Three different silicon nitride thicknesses allow the formation of three regions, inside the same device, each with different photocurrents and responsivity behaviors. We show that by selecting specific biases, the photoresponse of the regions can be switched on and off.
This peculiar behavior allows the device to be used as a photodetector with a voltage-dependent active surface. Scanning photo response imaging of the device surface, performed at different biases highlights this behavio
Contact resistance and mobility in back-gate graphene transistors
No full textThe metal-graphene contact resistance is one of the major limiting factors toward the technological
exploitation of graphene in electronic devices and sensors. High contact resistance can be detrimental
to device performance and spoil the intrinsic great properties of graphene. In this paper, we fabricate
back-gate graphene field-effect transistors with different geometries to study the contact and channel
resistance as well as the carrier mobility as a function of gate voltage and temperature. We apply the
transfer length method and the y-function method showing that the two approaches can complement
each other to evaluate the contact resistance and prevent artifacts in the estimation of carrier mobility
dependence on the gate-voltage. We find that the gate voltage modulates both the contact and the
channel resistance in a similar way but does not change the carrier mobility. We also show that raising
the temperature lowers the carrier mobility, has a negligible effect on the contact resistance, and can
induce a transition from a semiconducting to a metallic behavior of the graphene sheet resistance,
depending on the applied gate voltage. Finally, we show that eliminating the detrimental effects of the
contact resistance on the transistor channel current almost doubles the carrier field-effect mobility
and that a competitive contact resistance as low as 700 Ω·μm can be achieved by the zig-zag shaping of
the Ni contact
Spin polarized electron transport in a superconductor/ferromagnet junction with intermediate barrier strength
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Environmental Effects on the Electrical Characteristics of Back-Gated WSe2 Field-Effect Transistors
No full textWe study the effect of polymer coating, pressure, temperature, and light on the electrical
characteristics of monolayer WSe2 back-gated transistors with Ni/Au contacts. Our investigation
shows that the removal of a layer of poly(methyl methacrylate) (PMMA) or a decrease of the
pressure change the device conductivity from p- to n-type. From the temperature behavior of
the transistor transfer characteristics, a gate-tunable Schottky barrier at the contacts is demonstrated
and a barrier height of 70 meV in the flat-band condition is measured. We also report and discuss
a temperature-driven change in the mobility and the subthreshold swing that is used to estimate the
trap density at the WSe2/SiO2 interface. Finally, from studying the spectral photoresponse of the
WSe2, it is proven that the device can be used as a photodetector with a responsivity of 0.5 AW1
at 700 nm and 0.37 mW/cm2 optical power
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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