Special Issue "Nanoscale Electrical Characterization of Low Dimensional Materials for Electronics"

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: 31 December 2020.

Special Issue Editors

Dr. Filippo Giannazzo
Website
Guest Editor
Consiglio Nazionale delle Ricerche –Institute for Microelectronics and Microsystems (CNR-IMM), Strada VIII, 5 I-95121 Catania, Italy
Interests: graphene; 2D materials; wide-bandgap semiconductors (SiC, GaN); high power and high frequency electronics; scanning probe microscopy
Special Issues and Collections in MDPI journals
Dr. Umberto Celano
Website
Guest Editor
Interuniversitair Micro-Electronica Centrum (IMEC), Leuven Belgium
Interests: nanoelectronics; functional nanomaterials; 2D materials; VLSI metrology; scanning probe microscopy

Special Issue Information

Dear colleagues,

Low dimensional materials (including the broad family of 2D materials, 1D nanotube or nanowires and 0 D quantum dots) are currently gaining increasing interest in electronics/optoelectronics, as they allow us to extend the performance of traditional semiconductor devices or to demonstrate completely new device concepts and exciting physics.

In this context, combining nanometric spatial resolution with a wide range of physical properties that can be detected, scanning-probe-based characterization techniques have proved themselves to be essential tools to investigate the structural, electrical, chemical and optical properties of low dimensional systems and their heterojunctions with bulk (3D) semiconductors.

This Special Issue will be devoted to new developments in nanoscale electrical characterization techniques, and their applications to the analysis of low dimensional materials, including (i) synthesis, (ii) integration and (iii) novel device architectures. The Special Issue is open to correlation studies of local electrical/optical measurements with high resolution structural/chemical analyses, as well as to theoretical and modelling works for the interpretation of experimental results in these nanoscale systems.

It is our pleasure to invite you to submit a manuscript for this Special Issue. Full papers, short communications, and reviews are welcome.

Dr. Filippo Giannazzo
Dr. Umberto Celano
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Scanning Probe Microscopy
  • Scanning Tunneling Microscopy
  • Conductive Atomic Force Microscopy
  • Scanning Capacitance Microscopy
  • Scanning Microwave Impedance Microscopy
  • Kelvin Probe Force Microscopy
  • Scanning Near Field Optical Microscopy
  • 2D Materials
  • Nanowires
  • Quantum dots

Published Papers (6 papers)

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Research

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Open AccessArticle
Comprehensive Electrostatic Modeling of Exposed Quantum Dots in Graphene/Hexagonal Boron Nitride Heterostructures
Nanomaterials 2020, 10(6), 1154; https://doi.org/10.3390/nano10061154 - 12 Jun 2020
Abstract
Recent experimental advancements have enabled the creation of tunable localized electrostatic potentials in graphene/hexagonal boron nitride (hBN) heterostructures without concealing the graphene surface. These potentials corral graphene electrons yielding systems akin to electrostatically defined quantum dots (QDs). The spectroscopic characterization of these exposed [...] Read more.
Recent experimental advancements have enabled the creation of tunable localized electrostatic potentials in graphene/hexagonal boron nitride (hBN) heterostructures without concealing the graphene surface. These potentials corral graphene electrons yielding systems akin to electrostatically defined quantum dots (QDs). The spectroscopic characterization of these exposed QDs with the scanning tunneling microscope (STM) revealed intriguing resonances that are consistent with a tunneling probability of 100% across the QD walls. This effect, known as Klein tunneling, is emblematic of relativistic particles, underscoring the uniqueness of these graphene QDs. Despite the advancements with electrostatically defined graphene QDs, a complete understanding of their spectroscopic features still remains elusive. In this study, we address this lapse in knowledge by comprehensively considering the electrostatic environment of exposed graphene QDs. We then implement these considerations into tight binding calculations to enable simulations of the graphene QD local density of states. We find that the inclusion of the STM tip’s electrostatics in conjunction with that of the underlying hBN charges reproduces all of the experimentally resolved spectroscopic features. Our work provides an effective approach for modeling the electrostatics of exposed graphene QDs. The methods discussed here can be applied to other electrostatically defined QD systems that are also exposed. Full article
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Open AccessFeature PaperArticle
Dynamic Modification of Fermi Energy in Single-Layer Graphene by Photoinduced Electron Transfer from Carbon Dots
Nanomaterials 2020, 10(3), 528; https://doi.org/10.3390/nano10030528 - 15 Mar 2020
Abstract
Graphene (Gr)—a single layer of two-dimensional sp2 carbon atoms—and Carbon Dots (CDs)—a novel class of carbon nanoparticles—are two outstanding nanomaterials, renowned for their peculiar properties: Gr for its excellent charge-transport, and CDs for their impressive emission properties. Such features, coupled with a [...] Read more.
Graphene (Gr)—a single layer of two-dimensional sp2 carbon atoms—and Carbon Dots (CDs)—a novel class of carbon nanoparticles—are two outstanding nanomaterials, renowned for their peculiar properties: Gr for its excellent charge-transport, and CDs for their impressive emission properties. Such features, coupled with a strong sensitivity to the environment, originate the interest in bringing together these two nanomaterials in order to combine their complementary properties. In this work, the investigation of a solid-phase composite of CDs deposited on Gr is reported. The CD emission efficiency is reduced by the contact of Gr. At the same time, the Raman analysis of Gr demonstrates the increase of Fermi energy when it is in contact with CDs under certain conditions. The interaction between CDs and Gr is modeled in terms of an electron-transfer from photoexcited CDs to Gr, wherein an electron is first transferred from the carbon core to the surface states of CDs, and from there to Gr. There, the accumulated electrons determine a dynamical n-doping effect modulated by photoexcitation. The CD–graphene interaction unveiled herein is a step forward in the understanding of the mutual influence between carbon-based nanomaterials, with potential prospects in light conversion applications. Full article
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Open AccessArticle
Effect of Piezoresistive Behavior on Electron Emission from Individual Silicon Carbide Nanowire
Nanomaterials 2019, 9(7), 981; https://doi.org/10.3390/nano9070981 - 06 Jul 2019
Cited by 2
Abstract
The excellent properties of silicon carbide (SiC) make it widely applied in high-voltage, high-power, and high-temperature electronic devices. SiC nanowires combine the excellent physical properties of SiC material and the advantages of nanoscale structures, thus attracting significant attention from researchers. Herein, the electron [...] Read more.
The excellent properties of silicon carbide (SiC) make it widely applied in high-voltage, high-power, and high-temperature electronic devices. SiC nanowires combine the excellent physical properties of SiC material and the advantages of nanoscale structures, thus attracting significant attention from researchers. Herein, the electron vacuum tunneling emission characteristics of an individual SiC nanowire affected by the piezoresistive effect are investigated using in situ electric measurement in a scanning electron microscope (SEM) chamber. The results demonstrate that the piezoresistive effect caused by the electrostatic force has a significant impact on the electronic transport properties of the nanowire, and the excellent electron emission characteristics can be achieved in the pulse voltage driving mode, including lower turn-on voltage and higher maximum current. Furthermore, a physical model about the piezoresistive effect of SiC nanowire is proposed to explain the transformation of electronic transport under the action of electrostatic force in DC voltage and pulsed voltage driving modes. The findings can provide a way to obtain excellent electron emission characteristics from SiC nanowires. Full article
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Open AccessArticle
Pinch-Off Formation in Monolayer and Multilayers MoS2 Field-Effect Transistors
Nanomaterials 2019, 9(6), 882; https://doi.org/10.3390/nano9060882 - 14 Jun 2019
Cited by 2
Abstract
The discovery of layered materials, including transition metal dichalcogenides (TMD), gives rise to a variety of novel nanoelectronic devices, including fast switching field-effect transistors (FET), assembled heterostructures, flexible electronics, etc. Molybdenum disulfide (MoS2), a transition metal dichalcogenides semiconductor, is considered an [...] Read more.
The discovery of layered materials, including transition metal dichalcogenides (TMD), gives rise to a variety of novel nanoelectronic devices, including fast switching field-effect transistors (FET), assembled heterostructures, flexible electronics, etc. Molybdenum disulfide (MoS2), a transition metal dichalcogenides semiconductor, is considered an auspicious candidate for the post-silicon era due to its outstanding chemical and thermal stability. We present a Kelvin probe force microscopy (KPFM) study of a MoS2 FET device, showing direct evidence for pinch-off formation in the channel by in situ monitoring of the electrostatic potential distribution along the conducting channel of the transistor. In addition, we present a systematic comparison between a monolayer MoS2 FET and a few-layer MoS2 FET regarding gating effects, electric field distribution, depletion region, and pinch-off formation in such devices. Full article
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Open AccessArticle
Probing the Optical Properties of MoS2 on SiO2/Si and Sapphire Substrates
Nanomaterials 2019, 9(5), 740; https://doi.org/10.3390/nano9050740 - 14 May 2019
Cited by 3
Abstract
As an important supplementary material to graphene in the optoelectronics field, molybdenum disulfide (MoS2) has attracted attention from researchers due to its good light absorption capacity and adjustable bandgap. In this paper, MoS2 layers are respectively grown on SiO2 [...] Read more.
As an important supplementary material to graphene in the optoelectronics field, molybdenum disulfide (MoS2) has attracted attention from researchers due to its good light absorption capacity and adjustable bandgap. In this paper, MoS2 layers are respectively grown on SiO2/Si and sapphire substrates by atmospheric pressure chemical vapor deposition (APCVD). Atomic force microscopy, optical microscopy, and Raman and photoluminescence spectroscopy are used to probe the optical properties of MoS2 on SiO2/Si and sapphire substrates systematically. The peak shift between the characteristic A1g and E12g peaks increases, and the I peak of the PL spectrum on the SiO2/Si substrate redshifts slightly when the layer numbers were increased, which can help in obtaining the layer number and peak position of MoS2. Moreover, the difference from monolayer MoS2 on the SiO2/Si substrate is that the B peak of the PL spectrum has a blueshift of 56 meV and the characteristic E12g peak of the Raman spectrum has no blueshift. The 1- and 2-layer MoS2 on a sapphire substrate had a higher PL peak intensity than that of the SiO2/Si substrate. When the laser wavelength is transformed from 532 to 633 nm, the position of I exciton peak has a blueshift of 16 meV, and the PL intensity of monolayer MoS2 on the SiO2/Si substrate increases. The optical properties of MoS2 can be obtained, which is helpful for the fabrication of optoelectronic devices. Full article
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Review

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Open AccessReview
Conductive Atomic Force Microscopy of Semiconducting Transition Metal Dichalcogenides and Heterostructures
Nanomaterials 2020, 10(4), 803; https://doi.org/10.3390/nano10040803 - 22 Apr 2020
Cited by 1
Abstract
Semiconducting transition metal dichalcogenides (TMDs) are promising materials for future electronic and optoelectronic applications. However, their electronic properties are strongly affected by peculiar nanoscale defects/inhomogeneities (point or complex defects, thickness fluctuations, grain boundaries, etc.), which are intrinsic of these materials or introduced during [...] Read more.
Semiconducting transition metal dichalcogenides (TMDs) are promising materials for future electronic and optoelectronic applications. However, their electronic properties are strongly affected by peculiar nanoscale defects/inhomogeneities (point or complex defects, thickness fluctuations, grain boundaries, etc.), which are intrinsic of these materials or introduced during device fabrication processes. This paper reviews recent applications of conductive atomic force microscopy (C-AFM) to the investigation of nanoscale transport properties in TMDs, discussing the implications of the local phenomena in the overall behavior of TMD-based devices. Nanoscale resolution current spectroscopy and mapping by C-AFM provided information on the Schottky barrier uniformity and shed light on the mechanisms responsible for the Fermi level pinning commonly observed at metal/TMD interfaces. Methods for nanoscale tailoring of the Schottky barrier in MoS2 for the realization of ambipolar transistors are also illustrated. Experiments on local conductivity mapping in monolayer MoS2 grown by chemical vapor deposition (CVD) on SiO2 substrates are discussed, providing a direct evidence of the resistance associated to the grain boundaries (GBs) between MoS2 domains. Finally, C-AFM provided an insight into the current transport phenomena in TMD-based heterostructures, including lateral heterojunctions observed within MoxW1–xSe2 alloys, and vertical heterostructures made by van der Waals stacking of different TMDs (e.g., MoS2/WSe2) or by CVD growth of TMDs on bulk semiconductors. Full article
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