Publications by authors named "Davide Mencarelli"

8 Publications

  • Page 1 of 1

Reversing the Humidity Response of MoS- and WS-Based Sensors Using Transition-Metal Salts.

ACS Appl Mater Interfaces 2021 May 5;13(19):23201-23209. Epub 2021 May 5.

Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain.

Two-dimensional materials, such as transition-metal dichalcogenides (TMDs), are attractive candidates for sensing applications due to their high surface-to-volume ratio, chemically active edges, and good electrical properties. However, their electrical response to humidity is still under debate and experimental reports remain inconclusive. For instance, in different studies, the impedance of MoS-based sensors has been found to either decrease or increase with increasing humidity, compromising the use of MoS for humidity sensing. In this work, we focus on understanding the interaction between water and TMDs. We fabricated and studied humidity sensors based on MoS and WS coated with copper chloride and silver nitrate. The devices exhibited high chemical stability and excellent humidity sensing performance in relative humidity between 4 and 80%, with response and recovery times of 2 and 40 s, respectively. We have systematically investigated the humidity response of the materials as a function of the type and amount of induced metal salt and observed the reverse action of sensing mechanisms. This phenomenon is explained based on a detailed structural analysis of the samples considering the Grotthuss mechanism in the presence of charge trapping, which was represented by an appropriate lumped-element model. Our findings open up a possibility to tune the electrical response in a facile manner and without compromising the high performance of the sensor. They offer an insight into the time-dependent performance and aging of the TMD-based sensing devices.
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http://dx.doi.org/10.1021/acsami.1c03691DOI Listing
May 2021

Heterodyne phase shifting method in scanning probe microscopy.

J Opt Soc Am A Opt Image Sci Vis 2021 Mar;38(3):378-386

The present paper describes a novel implementation of the continuous phase shifting method (PSM), named heterodyne holography, in a scanning probe microscope configuration, able to retrieve the complex scattered field in on-axis configuration. This can be achieved by acquiring a continuous sequence of holograms at different wavelengths in just a single scan through the combination of scanning interference microscopy and a low-coherent signal acquired in the frequency domain. This method exploits the main advantages of the phase shifting technique and avoids some limits relative to off-axis holography in providing quantitative phase imaging.
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http://dx.doi.org/10.1364/JOSAA.415042DOI Listing
March 2021

Modeling and Electrochemical Characterization of Electrodes Based on Epoxy Composite with Functionalized Nanocarbon Fillers at High Concentration.

Nanomaterials (Basel) 2020 Apr 28;10(5). Epub 2020 Apr 28.

INFN-Laboratori Nazionali di Frascati, via E. Fermi 40, 00044 Frascati, Italy.

This paper deals with the electrochemical characterization and the equivalent circuit modeling of screen-printed electrodes, modified by an epoxy composite and loaded with carbon nanotubes (CNTs), pristine and functionalized NH, and graphene nanoplates (GNPs). The fabrication method is optimized in order to obtain a good dispersion even at high concentration, up to 10%, to increase the range of investigation. Due to the rising presence of filler on the surface, the cyclic voltammetric analysis shows an increasing of (i) electrochemical response and (ii) filler concentration as observed by the scanning electron microscopy (SEM). Epoxy/CNTs-NH and epoxy/GNPs, at 10% of concentration, show the best electrochemical behavior. Furthermore, epoxy/CNTs-NH show a lower percolation threshold than epoxy/CNT, probably due to the direct bond created by amino groups. Furthermore, the electrochemical impedance spectroscopy (EIS) is used to obtain an electrical equivalent circuit (EEC). The EEC model is a remarkable evolution of previous circuits present in the literature, by inserting an accurate description of the capacitive/inductive/resistive characteristics, thus leading to an enhanced knowledge of phenomena that occur during electrochemical processes.
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http://dx.doi.org/10.3390/nano10050850DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7712193PMC
April 2020

Advanced numerical investigation of the heat flux in an array of microbolometers.

Sci Rep 2019 Jul 31;9(1):11078. Epub 2019 Jul 31.

IHP Microelectronics, Im Technologiepark 25, 15236, Frankfurt (Oder), Germany.

The investigation of the thermal properties of an array of microbolometers has been carried out by mean of two independent numerical analysis, respectively the Direct-Simulation Monte Carlo (DSMC) and the classic diffusive approach of the Fourier's equation. In particular, the thermal dissipation of a hot membrane placed in a low-pressure cavity has been studied for different values of the temperature of the hot body and for different values of the pressure of the environment. The results for the heat flux derived from the two approaches have then been compared and discussed.
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http://dx.doi.org/10.1038/s41598-019-47472-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6668448PMC
July 2019

Vertically aligned CNT-Cu nano-composite material for stacked through-silicon-via interconnects.

Nanotechnology 2016 Aug 7;27(33):335705. Epub 2016 Jul 7.

SMIT Center, School of Mechanical Engineering and Automation and Institute of NanomicroEnergy, Jiading Campus, Shanghai University, 201800 Shanghai, People's Republic of China. Electronics Materials and Systems Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.

For future miniaturization of electronic systems using 3D chip stacking, new fine-pitch materials for through-silicon-via (TSV) applications are likely required. In this paper, we propose a novel carbon nanotube (CNT)/copper nanocomposite material consisting of high aspect ratio, vertically aligned CNT bundles coated with copper. These bundles, consisting of hundreds of tiny CNTs, were uniformly coated by copper through electroplating, and aspect ratios as high as 300:1 were obtained. The resistivity of this nanomaterial was found to be as low as ∼10(-8) Ω m, which is of the same order of magnitude as the resistivity of copper, and its temperature coefficient was found to be only half of that of pure copper. The main advantage of the composite TSV nanomaterial is that its coefficient of thermal expansion (CTE) is similar to that of silicon, a key reliability factor. A finite element model was set up to demonstrate the reliability of this composite material and thermal cycle simulations predicted very promising results. In conclusion, this composite nanomaterial appears to be a very promising material for future 3D TSV applications offering both a low resistivity and a low CTE similar to that of silicon.
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http://dx.doi.org/10.1088/0957-4484/27/33/335705DOI Listing
August 2016

Fast ultrahigh-density writing of low-conductivity patterns on semiconducting polymers.

Nat Commun 2013 ;4:2668

Department of Information Engineering, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.

The exceptional interest in improving the limitations of data storage, molecular electronics and optoelectronics has promoted the development of an ever increasing number of techniques used to pattern polymers at micro and nanoscale. Most of them rely on atomic force microscopy to thermally or electrostatically induce mass transport, thereby creating topographic features. Here we show that the mechanical interaction between the tip of the atomic force microscope and the surface of π-conjugated polymeric films produces a local increase of molecular disorder, inducing a localized lowering of the semiconductor conductivity, not associated to detectable modifications in the surface topography. This phenomenon allows for the swift production of low-conductivity patterns on the film surface at a speed exceeding 20 μm s⁻¹; paths have a resolution in the order of the tip size (20 nm) and are detected by a conducting-atomic force microscopy tip in the conductivity maps.
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http://dx.doi.org/10.1038/ncomms3668DOI Listing
June 2014

Disentangling time in a near-field approach to scanning probe microscopy.

Nanoscale 2011 Sep 1;3(9):3589-93. Epub 2011 Aug 1.

DIBET, Università Politecnica delle Marche, Via Brecce Bianche, 60131, Ancona, Italy.

Microwave microscopy has recently attracted intensive effort, owing to its capability to provide quantitative information about the local composition and the electromagnetic response of a sample. Nonetheless, the interpretation of microwave images remains a challenge as the electromagnetic waves interact with the sample and the surrounding in a multitude of ways following different paths: microwave images are a convolution of all contributions. In this work we show that examining the time evolution of the electromagnetic waves allows us to disentangle each contribution, providing images with striking quality and unexplored scenarios for near-field microscopy.
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http://dx.doi.org/10.1039/c1nr10491hDOI Listing
September 2011

A multichannel model for the self-consistent analysis of coherent transport in graphene nanoribbons.

ACS Nano 2011 Aug 12;5(8):6109-18. Epub 2011 Jul 12.

Dipartimento di Ingegneria Biomedica Elettronica e Telecomunicazioni, Università Politecnica delle Marche, Via Brecce Bianche, 60100 Ancona, Italy.

In this contribution, we analyze the multichannel coherent transport in graphene nanoribbons (GNRs) by a scattering matrix approach. We consider the transport properties of GNR devices of a very general form, involving multiple bands and multiple leads. The 2D quantum transport over the whole GNR surface, described by the Schrödinger equation, is strongly nonlinear as it implies calculation of self-generated and externally applied electrostatic potentials, solutions of the 3D Poisson equation. The surface charge density is computed as a balance of carriers traveling through the channel at all of the allowed energies. Moreover, formation of bound charges corresponding to a discrete modal spectrum is observed and included in the model. We provide simulation examples by considering GNR configurations typical for transistor devices and GNR protrusions that find an interesting application as cold cathodes for X-ray generation. With reference to the latter case, a unified model is required in order to couple charge transport and charge emission. However, to a first approximation, these could be considered as independent problems, as in the example.
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http://dx.doi.org/10.1021/nn2011333DOI Listing
August 2011