Nanotechnology for Electronic Materials and Devices

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Nanoelectronics, Nanosensors and Devices".

Deadline for manuscript submissions: closed (15 May 2022) | Viewed by 33045

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Consiglio Nazionale delle Ricerche, Insituto per la Microelettronica e Microsistemi, Catania, Italy
Interests: nanoscaled and nanostructured materials; wide band gap semiconductor; nanoscaled heterostructures; advanced nanoscale characterization techniques; advanced semiconductors

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Consiglio Nazionale delle Ricerche–Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII n. 5, Zona Industriale, 95121 Catania, Italy
Interests: atomic layer deposition; dielectrics; thin films; oxides; nitrides; chemical vapor deposition; power devices; wide band gap semiconductors

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Institute for Technical Physics and Materials Science, Budapest, Hungary

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Linköping University | LiU · Department of Physics, Chemistry and Biology (IFM), Linköping, Sweden
Interests: Semiconductors; 2D materials; sensors

Special Issue Information

Dear Colleagues,

Among the principal goals of the International Roadmap for Devices and Systems, the historical scaling down of electronic devices is now coupled with the need for novel nanomaterials and emerging characterization and fabrication techniques focused on interaction at the nanoscale. Nanomaterials for electronic devices are of growing interest, since their reduced dimensionality can be associated with unique properties which are currently finding rapid application in many technological areas (such as high-frequency electronics, power devices, displays, energy conversion systems, energy storage, photovoltaics, and sensors). On the other hand, the accurate characterization of materials and interfaces at the nanoscale, along with standard metrics and protocols, is crucial for moving from research to technology development in the field and for quality control of innovative products and functionalities.

This Special Issue will cover the most recent developments on nanomaterials and nanotechnologies for electronic devices and sensors, from synthesis to advanced characterization, up to device fabrication.

Specific topics covered by the issue are:

  • Nanoscaled material and their properties: nanostructured thin films (oxides, nitrides), nanocomposites, nanoparticles, and 2D materials (graphene or MX2 M = Mo, W, etc. and X = S, Se, Te, etc.);
  • Synthesis techniques for nanomaterials and thin films: processes and novel approaches;
  • Advanced nanoscale characterization techniques (surface analytical and scanning-probe methods, electron beam methods, optical methods, X-ray methods);
  • Applications of nanostructured materials and nanotechnologies to electronic devices (high frequency and power devices, photovoltaics, sensors, etc.).

Full research papers, communications, and reviews are all welcome.

Dr. Patrick Fiorenza
Dr. Raffaella Lo Nigro
Dr. Béla Pécz
Dr. Jens Eriksson
Guest Editors

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Published Papers (12 papers)

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Editorial

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2 pages, 201 KiB  
Editorial
Nanotechnology for Electronic Materials and Devices
by Raffaella Lo Nigro, Patrick Fiorenza, Béla Pécz and Jens Eriksson
Nanomaterials 2022, 12(19), 3319; https://doi.org/10.3390/nano12193319 - 23 Sep 2022
Cited by 4 | Viewed by 1670
Abstract
The historical scaling down of electronics devices is no longer the main goal of the International Roadmap for Devices and Systems [...] Full article
(This article belongs to the Special Issue Nanotechnology for Electronic Materials and Devices)

Research

Jump to: Editorial

18 pages, 5826 KiB  
Article
Memory Effects in Nanolaminates of Hafnium and Iron Oxide Films Structured by Atomic Layer Deposition
by Kristjan Kalam, Markus Otsus, Jekaterina Kozlova, Aivar Tarre, Aarne Kasikov, Raul Rammula, Joosep Link, Raivo Stern, Guillermo Vinuesa, José Miguel Lendínez, Salvador Dueñas, Helena Castán, Aile Tamm and Kaupo Kukli
Nanomaterials 2022, 12(15), 2593; https://doi.org/10.3390/nano12152593 - 28 Jul 2022
Cited by 5 | Viewed by 1438
Abstract
HfO2 and Fe2O3 thin films and laminated stacks were grown by atomic layer deposition at 350 °C from hafnium tetrachloride, ferrocene, and ozone. Nonlinear, saturating, and hysteretic magnetization was recorded in the films. Magnetization was expectedly dominated by increasing [...] Read more.
HfO2 and Fe2O3 thin films and laminated stacks were grown by atomic layer deposition at 350 °C from hafnium tetrachloride, ferrocene, and ozone. Nonlinear, saturating, and hysteretic magnetization was recorded in the films. Magnetization was expectedly dominated by increasing the content of Fe2O3. However, coercive force could also be enhanced by the choice of appropriate ratios of HfO2 and Fe2O3 in nanolaminated structures. Saturation magnetization was observed in the measurement temperature range of 5–350 K, decreasing towards higher temperatures and increasing with the films’ thicknesses and crystal growth. Coercive force tended to increase with a decrease in the thickness of crystallized layers. The films containing insulating HfO2 layers grown alternately with magnetic Fe2O3 exhibited abilities to both switch resistively and magnetize at room temperature. Resistive switching was unipolar in all the oxides mounted between Ti and TiN electrodes. Full article
(This article belongs to the Special Issue Nanotechnology for Electronic Materials and Devices)
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16 pages, 10882 KiB  
Article
Investigation of Combinatorial WO3-MoO3 Mixed Layers by Spectroscopic Ellipsometry Using Different Optical Models
by Miklos Fried, Renato Bogar, Daniel Takacs, Zoltan Labadi, Zsolt Endre Horvath and Zsolt Zolnai
Nanomaterials 2022, 12(14), 2421; https://doi.org/10.3390/nano12142421 - 14 Jul 2022
Cited by 4 | Viewed by 1581
Abstract
Reactive (Ar-O2 plasma) magnetron sputtered WO3-MoO3 (nanometer scaled) mixed layers were investigated and mapped by Spectroscopic Ellipsometry (SE). The W- and Mo-targets were placed separately, and 30 × 30 cm glass substrates were slowly moved under the two (W [...] Read more.
Reactive (Ar-O2 plasma) magnetron sputtered WO3-MoO3 (nanometer scaled) mixed layers were investigated and mapped by Spectroscopic Ellipsometry (SE). The W- and Mo-targets were placed separately, and 30 × 30 cm glass substrates were slowly moved under the two (W and Mo) separated targets. We used different (oscillator- and Effective Medium Approximation, EMA-based) optical models to obtain the thickness and composition maps of the sample layer relatively quickly and in a cost-effective and contactless way. In addition, we used Rutherford Backscattering Spectrometry to check the SE results. Herein, we compare the “goodness” of different optical models depending upon the sample preparation conditions, for instance, the speed and cycle number of the substrate motion. Finally, we can choose between appropriate optical models (2-Tauc-Lorentz oscillator model vs. the Bruggeman Effective Medium Approximation, BEMA) depending on the process parameters. If one has more than one “molecular layer” in the “sublayers”, BEMA can be used. If one has an atomic mixture, the multiple oscillator model is better (more precise) for this type of layer structure. Full article
(This article belongs to the Special Issue Nanotechnology for Electronic Materials and Devices)
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9 pages, 6214 KiB  
Article
Device and Circuit Analysis of Double Gate Field Effect Transistor with Mono-Layer WS2-Channel at Sub-2 nm Technology Node
by Jihun Park, Changho Ra, Jaewon Lim and Jongwook Jeon
Nanomaterials 2022, 12(13), 2299; https://doi.org/10.3390/nano12132299 - 04 Jul 2022
Cited by 3 | Viewed by 2131
Abstract
In this work, WS2 was adopted as a channel material among transition metal dichalcogenides (TMD) materials that have recently been in the spotlight, and the circuit power performance (power consumption, operating frequency) of the monolayer WS2 field-effect transistor with a double [...] Read more.
In this work, WS2 was adopted as a channel material among transition metal dichalcogenides (TMD) materials that have recently been in the spotlight, and the circuit power performance (power consumption, operating frequency) of the monolayer WS2 field-effect transistor with a double gate structure (DG WS2-FET) was analyzed. It was confirmed that the effective capacitance, which is circuit power performance, was greatly changed by the extrinsic capacitance components of DG WS2-FET, and the spacer region length (LSPC) and dielectric constant (KSPC) values of the spacer that could affect the extrinsic capacitance components were analyzed to identify the circuit power performance. As a result, when LSPC is increased by 1.5 nm with the typical spacer material (KSPC = 7.5), increased operating speed (+4.9%) and reduced active power (–6.8%) are expected. In addition, it is expected that the spacer material improvement by developing the low-k spacer from KSPC = 7.5 to KSPC = 2 at typical LSPC = 8 nm can increase the operating speed by 36.8% while maintaining similar active power consumption. Considering back-end-of-line (BEOL), the change in circuit power performance according to wire length was also analyzed. From these results, it can be seen that reducing the capacitance components of the extrinsic region is very important for improving the circuit power performance of the DG WS2-FET. Full article
(This article belongs to the Special Issue Nanotechnology for Electronic Materials and Devices)
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19 pages, 7563 KiB  
Article
Boxcar Averaging Scanning Nonlinear Dielectric Microscopy
by Kohei Yamasue and Yasuo Cho
Nanomaterials 2022, 12(5), 794; https://doi.org/10.3390/nano12050794 - 26 Feb 2022
Cited by 1 | Viewed by 1771
Abstract
Scanning nonlinear dielectric microscopy (SNDM) is a near-field microwave-based scanning probe microscopy method with a wide variety of applications, especially in the fields of dielectrics and semiconductors. This microscopy method has often been combined with contact-mode atomic force microscopy (AFM) for simultaneous topography [...] Read more.
Scanning nonlinear dielectric microscopy (SNDM) is a near-field microwave-based scanning probe microscopy method with a wide variety of applications, especially in the fields of dielectrics and semiconductors. This microscopy method has often been combined with contact-mode atomic force microscopy (AFM) for simultaneous topography imaging and contact force regulation. The combination SNDM with intermittent contact AFM is also beneficial for imaging a sample prone to damage and using a sharp microscopy tip for improving spatial resolution. However, SNDM with intermittent contact AFM can suffer from a lower signal-to-noise (S/N) ratio than that with contact-mode AFM because of the shorter contact time for a given measurement time. In order to improve the S/N ratio, we apply boxcar averaging based signal acquisition suitable for SNDM with intermittent contact AFM. We develop a theory for the S/N ratio of SNDM and experimentally demonstrate the enhancement of the S/N ratio in SNDM combined with peak-force tapping (a trademark of Bruker) AFM. In addition, we apply the proposed method to the carrier concentration distribution imaging of atomically thin van der Waals semiconductors. The proposed method clearly visualizes an anomalous electron doping effect on few-layer Nb-doped MoS2. The proposed method is also applicable to other scanning near-field microwave microscopes combined with peak-force tapping AFM such as scanning microwave impedance microscopy. Our results indicate the possibility of simultaneous nanoscale topographic, electrical, and mechanical imaging even on delicate samples. Full article
(This article belongs to the Special Issue Nanotechnology for Electronic Materials and Devices)
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15 pages, 4229 KiB  
Article
Multiscale Investigation of the Structural, Electrical and Photoluminescence Properties of MoS2 Obtained by MoO3 Sulfurization
by Salvatore E. Panasci, Antal Koos, Emanuela Schilirò, Salvatore Di Franco, Giuseppe Greco, Patrick Fiorenza, Fabrizio Roccaforte, Simonpietro Agnello, Marco Cannas, Franco M. Gelardi, Attila Sulyok, Miklos Nemeth, Béla Pécz and Filippo Giannazzo
Nanomaterials 2022, 12(2), 182; https://doi.org/10.3390/nano12020182 - 06 Jan 2022
Cited by 15 | Viewed by 2554
Abstract
In this paper, we report a multiscale investigation of the compositional, morphological, structural, electrical, and optical emission properties of 2H-MoS2 obtained by sulfurization at 800 °C of very thin MoO3 films (with thickness ranging from ~2.8 nm to ~4.2 nm) on [...] Read more.
In this paper, we report a multiscale investigation of the compositional, morphological, structural, electrical, and optical emission properties of 2H-MoS2 obtained by sulfurization at 800 °C of very thin MoO3 films (with thickness ranging from ~2.8 nm to ~4.2 nm) on a SiO2/Si substrate. XPS analyses confirmed that the sulfurization was very effective in the reduction of the oxide to MoS2, with only a small percentage of residual MoO3 present in the final film. High-resolution TEM/STEM analyses revealed the formation of few (i.e., 2–3 layers) of MoS2 nearly aligned with the SiO2 surface in the case of the thinnest (~2.8 nm) MoO3 film, whereas multilayers of MoS2 partially standing up with respect to the substrate were observed for the ~4.2 nm one. Such different configurations indicate the prevalence of different mechanisms (i.e., vapour-solid surface reaction or S diffusion within the film) as a function of the thickness. The uniform thickness distribution of the few-layer and multilayer MoS2 was confirmed by Raman mapping. Furthermore, the correlative plot of the characteristic A1g-E2g Raman modes revealed a compressive strain (ε ≈ −0.78 ± 0.18%) and the coexistence of n- and p-type doped areas in the few-layer MoS2 on SiO2, where the p-type doping is probably due to the presence of residual MoO3. Nanoscale resolution current mapping by C-AFM showed local inhomogeneities in the conductivity of the few-layer MoS2, which are well correlated to the lateral changes in the strain detected by Raman. Finally, characteristic spectroscopic signatures of the defects/disorder in MoS2 films produced by sulfurization were identified by a comparative analysis of Raman and photoluminescence (PL) spectra with CVD grown MoS2 flakes. Full article
(This article belongs to the Special Issue Nanotechnology for Electronic Materials and Devices)
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10 pages, 2672 KiB  
Article
Highly Homogeneous Current Transport in Ultra-Thin Aluminum Nitride (AlN) Epitaxial Films on Gallium Nitride (GaN) Deposited by Plasma Enhanced Atomic Layer Deposition
by Emanuela Schilirò, Filippo Giannazzo, Salvatore Di Franco, Giuseppe Greco, Patrick Fiorenza, Fabrizio Roccaforte, Paweł Prystawko, Piotr Kruszewski, Mike Leszczynski, Ildiko Cora, Béla Pécz, Zsolt Fogarassy and Raffaella Lo Nigro
Nanomaterials 2021, 11(12), 3316; https://doi.org/10.3390/nano11123316 - 07 Dec 2021
Cited by 6 | Viewed by 2885
Abstract
This paper reports an investigation of the structural, chemical and electrical properties of ultra-thin (5 nm) aluminum nitride (AlN) films grown by plasma enhanced atomic layer deposition (PE-ALD) on gallium nitride (GaN). A uniform and conformal coverage of the GaN substrate was demonstrated [...] Read more.
This paper reports an investigation of the structural, chemical and electrical properties of ultra-thin (5 nm) aluminum nitride (AlN) films grown by plasma enhanced atomic layer deposition (PE-ALD) on gallium nitride (GaN). A uniform and conformal coverage of the GaN substrate was demonstrated by morphological analyses of as-deposited AlN films. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) analyses showed a sharp epitaxial interface with GaN for the first AlN atomic layers, while a deviation from the perfect wurtzite stacking and oxygen contamination were detected in the upper part of the film. This epitaxial interface resulted in the formation of a two-dimensional electron gas (2DEG) with a sheet charge density ns ≈ 1.45 × 1012 cm−2, revealed by Hg-probe capacitance–voltage (C–V) analyses. Nanoscale resolution current mapping and current–voltage (I–V) measurements by conductive atomic force microscopy (C-AFM) showed a highly homogeneous current transport through the 5 nm AlN barrier, while a uniform flat-band voltage (VFB ≈ 0.3 V) for the AlN/GaN heterostructure was demonstrated by scanning capacitance microscopy (SCM). Electron transport through the AlN film was shown to follow the Fowler–Nordheim (FN) tunneling mechanism with an average barrier height of <ΦB> = 2.08 eV, in good agreement with the expected AlN/GaN conduction band offset. Full article
(This article belongs to the Special Issue Nanotechnology for Electronic Materials and Devices)
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14 pages, 8185 KiB  
Article
Structural Characteristics of the Si Whiskers Grown by Ni-Metal-Induced-Lateral-Crystallization
by Béla Pécz, Nikolaos Vouroutzis, György Zoltán Radnóczi, Nikolaos Frangis and John Stoemenos
Nanomaterials 2021, 11(8), 1878; https://doi.org/10.3390/nano11081878 - 22 Jul 2021
Cited by 5 | Viewed by 1864
Abstract
Si whiskers grown by Ni-Metal-Induced-Lateral-Crystallization (Ni-MILC) were grown at 413 °C, intentionally below the threshold for Solid State Crystallization, which is 420 °C. These whiskers have significant common characteristics with whiskers grown by the Vapor Liquid Solid (VLS) method. The crystalline quality of [...] Read more.
Si whiskers grown by Ni-Metal-Induced-Lateral-Crystallization (Ni-MILC) were grown at 413 °C, intentionally below the threshold for Solid State Crystallization, which is 420 °C. These whiskers have significant common characteristics with whiskers grown by the Vapor Liquid Solid (VLS) method. The crystalline quality of the whiskers in both methods is the same. However, in VLS, a crystalline substrate is required, in contrast to the amorphous one in Ni-MILC for the growth of single crystalline whiskers. Moreover, whiskers grown by VLS have a polygonal cross-section with their diameter determined by the diameter of the hemispherical metallic catalysts. On the other hand, in the Ni-MILC, the cross-section of the whiskers depends on the size of the NiSi2 grain from which they are emanated. This was confirmed by observing the crossing whiskers and the rotational Moiré patterns in the crossing area. The structure of disturbed short and thin nonlinear branches on the side-walls of the whiskers was studied. In the whiskers grown by the VLS method, significant contamination occurs by the metallic catalyst degrading the electrical characteristics of the whisker. Such Si whiskers are not compatible with the current CMOS process. Whiskers grown by Ni-MILC at 413 °C are also contaminated by Ni. However, the excess Ni is in the form of tetrahedral NiSi2 inclusions which are coherent with the Si matrix due to the very low misfit of 0.4% between them. These whiskers are compatible with current CMOS process and Thin Film Transistors (TFTs). Full article
(This article belongs to the Special Issue Nanotechnology for Electronic Materials and Devices)
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11 pages, 2787 KiB  
Article
High-Resolution Two-Dimensional Imaging of the 4H-SiC MOSFET Channel by Scanning Capacitance Microscopy
by Patrick Fiorenza, Mario S. Alessandrino, Beatrice Carbone, Alfio Russo, Fabrizio Roccaforte and Filippo Giannazzo
Nanomaterials 2021, 11(6), 1626; https://doi.org/10.3390/nano11061626 - 21 Jun 2021
Cited by 9 | Viewed by 2540
Abstract
In this paper, a two-dimensional (2D) planar scanning capacitance microscopy (SCM) method is used to visualize with a high spatial resolution the channel region of large-area 4H-SiC power MOSFETs and estimate the homogeneity of the channel length over the whole device perimeter. The [...] Read more.
In this paper, a two-dimensional (2D) planar scanning capacitance microscopy (SCM) method is used to visualize with a high spatial resolution the channel region of large-area 4H-SiC power MOSFETs and estimate the homogeneity of the channel length over the whole device perimeter. The method enabled visualizing the fluctuations of the channel geometry occurring under different processing conditions. Moreover, the impact of the ion implantation parameters on the channel could be elucidated. Full article
(This article belongs to the Special Issue Nanotechnology for Electronic Materials and Devices)
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11 pages, 2567 KiB  
Article
Effect of Back-Gate Voltage on the High-Frequency Performance of Dual-Gate MoS2 Transistors
by Qingguo Gao, Chongfu Zhang, Ping Liu, Yunfeng Hu, Kaiqiang Yang, Zichuan Yi, Liming Liu, Xinjian Pan, Zhi Zhang, Jianjun Yang and Feng Chi
Nanomaterials 2021, 11(6), 1594; https://doi.org/10.3390/nano11061594 - 17 Jun 2021
Cited by 7 | Viewed by 4244
Abstract
As an atomically thin semiconductor, 2D molybdenum disulfide (MoS2) has demonstrated great potential in realizing next-generation logic circuits, radio-frequency (RF) devices and flexible electronics. Although various methods have been performed to improve the high-frequency characteristics of MoS2 RF transistors, the [...] Read more.
As an atomically thin semiconductor, 2D molybdenum disulfide (MoS2) has demonstrated great potential in realizing next-generation logic circuits, radio-frequency (RF) devices and flexible electronics. Although various methods have been performed to improve the high-frequency characteristics of MoS2 RF transistors, the impact of the back-gate bias on dual-gate MoS2 RF transistors is still unexplored. In this work, we study the effect of back-gate control on the static and RF performance metrics of MoS2 high-frequency transistors. By using high-quality chemical vapor deposited bilayer MoS2 as channel material, high-performance top-gate transistors with on/off ratio of 107 and on-current up to 179 μA/μm at room temperature were realized. With the back-gate modulation, the source and drain contact resistances decrease to 1.99 kΩ∙μm at Vbg = 3 V, and the corresponding on-current increases to 278 μA/μm. Furthermore, both cut-off frequency and maximum oscillation frequency improves as the back-gate voltage increases to 3 V. In addition, a maximum intrinsic fmax of 29.7 GHz was achieved, which is as high as 2.1 times the fmax without the back-gate bias. This work provides significant insights into the influence of back-gate voltage on MoS2 RF transistors and presents the potential of dual-gate MoS2 RF transistors for future high-frequency applications. Full article
(This article belongs to the Special Issue Nanotechnology for Electronic Materials and Devices)
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12 pages, 3087 KiB  
Article
Enhanced Electrical Performance of Monolayer MoS2 with Rare Earth Element Sm Doping
by Shijie Li, Shidai Tian, Yuan Yao, Meng He, Li Chen, Yan Zhang and Junyi Zhai
Nanomaterials 2021, 11(3), 769; https://doi.org/10.3390/nano11030769 - 18 Mar 2021
Cited by 13 | Viewed by 6017
Abstract
Rare earth (RE) element-doped two-dimensional (2D) transition metal dichalcogenides (TMDCs) with applications in luminescence and magnetics have received considerable attention in recent years. To date, the effect of RE element doping on the electronic properties of monolayer 2D-TMDCs remains unanswered due to challenges [...] Read more.
Rare earth (RE) element-doped two-dimensional (2D) transition metal dichalcogenides (TMDCs) with applications in luminescence and magnetics have received considerable attention in recent years. To date, the effect of RE element doping on the electronic properties of monolayer 2D-TMDCs remains unanswered due to challenges including the difficulty of achieving valid monolayer doping and introducing RE elements with distinct valence and atomic configurations. Herein, we report a unique strategy to grow the Sm-doped monolayer MoS2 film by using an atmospheric pressure chemical vapor deposition method with the substrate face down on top of the growth source. A stable monolayer triangular Sm-doped MoS2 was achieved. The threshold voltage of an Sm-doped MoS2-based field effect transistor (FET) moved from −12 to 0 V due to the p-type character impurity state introduced by Sm ions in monolayer MoS2. Additionally, the electrical performance of the monolayer MoS2-based FET was improved by RE element Sm doping, including a 500% increase of the on/off current ratio and a 40% increase of the FET’s mobility. The electronic property enhancement resulted from Sm doping MoS2, which led internal lattice strain and changes in Fermi energy levels. These findings provide a general approach to synthesize RE element-doped monolayer 2D-TMDCs and to enrich their applications in electrical devices. Full article
(This article belongs to the Special Issue Nanotechnology for Electronic Materials and Devices)
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9 pages, 3857 KiB  
Article
A Rational Fabrication Method for Low Switching-Temperature VO2
by László Pósa, György Molnár, Benjamin Kalas, Zsófia Baji, Zsolt Czigány, Péter Petrik and János Volk
Nanomaterials 2021, 11(1), 212; https://doi.org/10.3390/nano11010212 - 15 Jan 2021
Cited by 12 | Viewed by 1783
Abstract
Due to its remarkable switching effect in electrical and optical properties, VO2 is a promising material for several applications. However, the stoichiometry control of multivalent vanadium oxides, especially with a rational deposition technique, is still challenging. Here, we propose and optimize a [...] Read more.
Due to its remarkable switching effect in electrical and optical properties, VO2 is a promising material for several applications. However, the stoichiometry control of multivalent vanadium oxides, especially with a rational deposition technique, is still challenging. Here, we propose and optimize a simple fabrication method for VO2 rich layers by the oxidation of metallic vanadium in atmospheric air. It was shown that a sufficiently broad annealing time window of 3.0–3.5 h can be obtained at an optimal oxidation temperature of 400 °C. The presence of VO2 was detected by selected area diffraction in a transmission electron microscope. According to the temperature dependent electrical measurements, the resistance contrast (R30 °C/R100 °C) varied between 44 and 68, whereas the optical switching was confirmed using in situ spectroscopic ellipsometric measurement by monitoring the complex refractive indices. The obtained phase transition temperature, both for the electrical resistance and for the ellipsometric angles, was found to be 49 ± 7 °C, i.e., significantly lower than that of the bulk VO2 of 68 ± 6 °C. Full article
(This article belongs to the Special Issue Nanotechnology for Electronic Materials and Devices)
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