1
|
Yasir M, Peinetti F, Savi P. Enhanced Graphene Based Electronically Tunable Phase Shifter. MICROMACHINES 2023; 14:1877. [PMID: 37893314 PMCID: PMC10608978 DOI: 10.3390/mi14101877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/22/2023] [Accepted: 09/28/2023] [Indexed: 10/29/2023]
Abstract
In this work, an enhanced tunable microwave phase shifter is presented. The phase shifter consists of three short circuited stubs and a tapered line. The stubs are connected to graphene pads. Graphene's tunable conductivity is varied by a DC voltage. This in turn causes a reactance variation at the input of the tapered line, which causes a phase variation. The physical parameters of the stubs are optimized for a maximum reactance variation by the help of analytical models, circuit and full wave simulations. Measurements of an optimized prototype are performed and a dynamic phase variation of 59∘ is obtained with an amplitude variation of less than 1 dB.
Collapse
Affiliation(s)
- Muhammad Yasir
- Division of Microrobotics and Control Engineering, Department of Computing Science, University of Oldenburg, 26129 Oldenburg, Germany
| | - Fabio Peinetti
- Department of Electronics and Telecommunications, Politecnico di Torino, 10129 Torino, Italy; (F.P.); (P.S.)
| | - Patrizia Savi
- Department of Electronics and Telecommunications, Politecnico di Torino, 10129 Torino, Italy; (F.P.); (P.S.)
| |
Collapse
|
2
|
Rodríguez-Villanueva S, Mendoza F, Weiner BR, Morell G. Graphene Film Growth on Silicon Carbide by Hot Filament Chemical Vapor Deposition. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:3033. [PMID: 36080070 PMCID: PMC9458213 DOI: 10.3390/nano12173033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/24/2022] [Accepted: 08/27/2022] [Indexed: 06/15/2023]
Abstract
The electrical properties of graphene on dielectric substrates, such as silicon carbide (SiC), have received much attention due to their interesting applications. This work presents a method to grow graphene on a 6H-SiC substrate at a pressure of 35 Torr by using the hot filament chemical vapor deposition (HFCVD) technique. The graphene deposition was conducted in an atmosphere of methane and hydrogen at a temperature of 950 °C. The graphene films were analyzed using Raman spectroscopy, scanning electron microscopy, atomic force microscopy, energy dispersive X-ray, and X-ray photoelectron spectroscopy. Raman mapping and AFM measurements indicated that few-layer and multilayer graphene were deposited from the external carbon source depending on the growth parameter conditions. The compositional analysis confirmed the presence of graphene deposition on SiC substrates and the absence of any metal involved in the growth process.
Collapse
Affiliation(s)
- Sandra Rodríguez-Villanueva
- Department of Physics, College of Natural Science, Rio Piedras Campus, University of Puerto Rico, San Juan, PR 00925, USA
- Molecular Sciences Research Center, University of Puerto Rico, San Juan, PR 00927, USA
| | - Frank Mendoza
- Department of Physics, College of Arts and Sciences, Mayagüez Campus, University of Puerto Rico, Mayaguez, PR 00682, USA
| | - Brad R. Weiner
- Molecular Sciences Research Center, University of Puerto Rico, San Juan, PR 00927, USA
- Department of Chemistry, College of Natural Science, Rio Piedras Campus, University of Puerto Rico, San Juan, PR 00925, USA
| | - Gerardo Morell
- Department of Physics, College of Natural Science, Rio Piedras Campus, University of Puerto Rico, San Juan, PR 00925, USA
- Molecular Sciences Research Center, University of Puerto Rico, San Juan, PR 00927, USA
| |
Collapse
|
3
|
Hagita K, Murashima T, Kawakatsu T. Lamellar Domain Spacing of Symmetric Linear, Ring, and Four-Arm-Star Block Copolymer Blends. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Katsumi Hagita
- Department of Applied Physics, National Defense Academy, 1-10-20 Hashirimizu, Yokosuka 239-8686, Japan
| | - Takahiro Murashima
- Department of Physics, Tohoku University, 6-3 Aramaki-aza-Aoba, Aoba-ku, Sendai 980-8578, Japan
| | - Toshihiro Kawakatsu
- Department of Physics, Tohoku University, 6-3 Aramaki-aza-Aoba, Aoba-ku, Sendai 980-8578, Japan
| |
Collapse
|
4
|
Graphene Growth Directly on SiO 2/Si by Hot Filament Chemical Vapor Deposition. NANOMATERIALS 2021; 12:nano12010109. [PMID: 35010059 PMCID: PMC8746613 DOI: 10.3390/nano12010109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 10/21/2021] [Accepted: 10/26/2021] [Indexed: 11/17/2022]
Abstract
We report the first direct synthesis of graphene on SiO2/Si by hot-filament chemical vapor deposition. Graphene deposition was conducted at low pressures (35 Torr) with a mixture of methane/hydrogen and a substrate temperature of 970 °C followed by spontaneous cooling to room temperature. A thin copper-strip was deposited in the middle of the SiO2/Si substrate as catalytic material. Raman spectroscopy mapping and atomic force microscopy measurements indicate the growth of few-layers of graphene over the entire SiO2/Si substrate, far beyond the thin copper-strip, while X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy showed negligible amounts of copper next to the initially deposited strip. The scale of the graphene nanocrystal was estimated by Raman spectroscopy and scanning electron microscopy.
Collapse
|
5
|
Wei T, Hauke F, Hirsch A. Evolution of Graphene Patterning: From Dimension Regulation to Molecular Engineering. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2104060. [PMID: 34569112 PMCID: PMC11468719 DOI: 10.1002/adma.202104060] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/28/2021] [Indexed: 05/26/2023]
Abstract
The realization that nanostructured graphene featuring nanoscale width can confine electrons to open its bandgap has aroused scientists' attention to the regulation of graphene structures, where the concept of graphene patterns emerged. Exploring various effective methods for creating graphene patterns has led to the birth of a new field termed graphene patterning, which has evolved into the most vigorous and intriguing branch of graphene research during the past decade. The efforts in this field have resulted in the development of numerous strategies to structure graphene, affording a variety of graphene patterns with tailored shapes and sizes. The established patterning approaches combined with graphene chemistry yields a novel chemical patterning route via molecular engineering, which opens up a new era in graphene research. In this review, the currently developed graphene patterning strategies is systematically outlined, with emphasis on the chemical patterning. In addition to introducing the basic concepts and the important progress of traditional methods, which are generally categorized into top-down, bottom-up technologies, an exhaustive review of established protocols for emerging chemical patterning is presented. At the end, an outlook for future development and challenges is proposed.
Collapse
Affiliation(s)
- Tao Wei
- Department of Chemistry and Pharmacy and Joint Institute of Advance Materials and Processes (ZMP)Friedrich‐Alexander University of Erlangen‐NürnbergNikolaus‐Fiebiger‐Strasse 1091058ErlangenGermany
| | - Frank Hauke
- Department of Chemistry and Pharmacy and Joint Institute of Advance Materials and Processes (ZMP)Friedrich‐Alexander University of Erlangen‐NürnbergNikolaus‐Fiebiger‐Strasse 1091058ErlangenGermany
| | - Andreas Hirsch
- Department of Chemistry and Pharmacy and Joint Institute of Advance Materials and Processes (ZMP)Friedrich‐Alexander University of Erlangen‐NürnbergNikolaus‐Fiebiger‐Strasse 1091058ErlangenGermany
| |
Collapse
|
6
|
Danielsen DR, Lyksborg-Andersen A, Nielsen KES, Jessen BS, Booth TJ, Doan MH, Zhou Y, Bøggild P, Gammelgaard L. Super-Resolution Nanolithography of Two-Dimensional Materials by Anisotropic Etching. ACS APPLIED MATERIALS & INTERFACES 2021; 13:41886-41894. [PMID: 34431654 DOI: 10.1021/acsami.1c09923] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nanostructuring allows altering of the electronic and photonic properties of two-dimensional (2D) materials. The efficiency, flexibility, and convenience of top-down lithography processes are, however, compromised by nanometer-scale edge roughness and resolution variability issues, which especially affect the performance of 2D materials. Here, we study how dry anisotropic etching of multilayer 2D materials with sulfur hexafluoride (SF6) may overcome some of these issues, showing results for hexagonal boron nitride (hBN), tungsten disulfide (WS2), tungsten diselenide (WSe2), molybdenum disulfide (MoS2), and molybdenum ditelluride (MoTe2). Scanning electron microscopy and transmission electron microscopy reveal that etching leads to anisotropic hexagonal features in the studied transition metal dichalcogenides, with the relative degree of anisotropy ranked as: WS2 > WSe2 > MoTe2 ∼ MoS2. Etched holes are terminated by zigzag edges while etched dots (protrusions) are terminated by armchair edges. This can be explained by Wulff constructions, taking the relative stabilities of the edges and the AA' stacking order into account. Patterns in WS2 are transferred to an underlying graphite layer, demonstrating a possible use for creating sub-10 nm features. In contrast, multilayer hBN exhibits no lateral anisotropy but shows consistent vertical etch angles, independent of crystal orientation. Using an hBN crystal as the base, ultrasharp corners can be created in lithographic patterns, which are then transferred to a graphite crystal underneath. We find that the anisotropic SF6 reactive ion etching process makes it possible to downsize nanostructures and obtain smooth edges, sharp corners, and feature sizes significantly below the resolution limit of electron beam lithography. The nanostructured 2D materials can be used themselves or as etch masks to pattern other nanomaterials.
Collapse
Affiliation(s)
- Dorte R Danielsen
- Department of Physics, Technical University of Denmark (DTU), Kgs. Lyngby 2800, Denmark
- Centre for Nanostructured Graphene (CNG), Technical University of Denmark, Ørsteds Plads 345C, Kgs. Lyngby DK-2800, Denmark
| | - Anton Lyksborg-Andersen
- Centre for Nanostructured Graphene (CNG), Technical University of Denmark, Ørsteds Plads 345C, Kgs. Lyngby DK-2800, Denmark
- DTU Nanolab - National Centre for Nano Fabrication and Characterization, Technical University of Denmark (DTU), Kgs. Lyngby 2800, Denmark
| | - Kirstine E S Nielsen
- Department of Physics, Technical University of Denmark (DTU), Kgs. Lyngby 2800, Denmark
- Centre for Nanostructured Graphene (CNG), Technical University of Denmark, Ørsteds Plads 345C, Kgs. Lyngby DK-2800, Denmark
| | - Bjarke S Jessen
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Timothy J Booth
- Department of Physics, Technical University of Denmark (DTU), Kgs. Lyngby 2800, Denmark
- Centre for Nanostructured Graphene (CNG), Technical University of Denmark, Ørsteds Plads 345C, Kgs. Lyngby DK-2800, Denmark
| | - Manh-Ha Doan
- Department of Physics, Technical University of Denmark (DTU), Kgs. Lyngby 2800, Denmark
- Centre for Nanostructured Graphene (CNG), Technical University of Denmark, Ørsteds Plads 345C, Kgs. Lyngby DK-2800, Denmark
| | - Yingqiu Zhou
- Department of Physics, Technical University of Denmark (DTU), Kgs. Lyngby 2800, Denmark
- Centre for Nanostructured Graphene (CNG), Technical University of Denmark, Ørsteds Plads 345C, Kgs. Lyngby DK-2800, Denmark
| | - Peter Bøggild
- Department of Physics, Technical University of Denmark (DTU), Kgs. Lyngby 2800, Denmark
- Centre for Nanostructured Graphene (CNG), Technical University of Denmark, Ørsteds Plads 345C, Kgs. Lyngby DK-2800, Denmark
| | - Lene Gammelgaard
- Department of Physics, Technical University of Denmark (DTU), Kgs. Lyngby 2800, Denmark
- Centre for Nanostructured Graphene (CNG), Technical University of Denmark, Ørsteds Plads 345C, Kgs. Lyngby DK-2800, Denmark
| |
Collapse
|
7
|
Hagita K, Aoyagi T, Abe Y, Genda S, Honda T. Deep learning-based estimation of Flory-Huggins parameter of A-B block copolymers from cross-sectional images of phase-separated structures. Sci Rep 2021; 11:12322. [PMID: 34112914 PMCID: PMC8192782 DOI: 10.1038/s41598-021-91761-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 05/31/2021] [Indexed: 02/05/2023] Open
Abstract
In this study, deep learning (DL)-based estimation of the Flory-Huggins χ parameter of A-B diblock copolymers from two-dimensional cross-sectional images of three-dimensional (3D) phase-separated structures were investigated. 3D structures with random networks of phase-separated domains were generated from real-space self-consistent field simulations in the 25-40 χN range for chain lengths (N) of 20 and 40. To confirm that the prepared data can be discriminated using DL, image classification was performed using the VGG-16 network. We comprehensively investigated the performances of the learned networks in the regression problem. The generalization ability was evaluated from independent images with the unlearned χN. We found that, except for large χN values, the standard deviation values were approximately 0.1 and 0.5 for A-component fractions of 0.2 and 0.35, respectively. The images for larger χN values were more difficult to distinguish. In addition, the learning performances for the 4-class problem were comparable to those for the 8-class problem, except when the χN values were large. This information is useful for the analysis of real experimental image data, where the variation of samples is limited.
Collapse
Affiliation(s)
- Katsumi Hagita
- Department of Applied Physics, National Defense Academy, 1-10-20 Hashirimizu, Yokosuka, 239-8686, Japan.
| | - Takeshi Aoyagi
- Research Center for Computational Design of Advanced Functional Materials, National Institute of Advanced Industrial Science and Technology, Central 2, 1-1-1, Umezono, Tsukuba, Ibaraki, 305-8568, Japan
| | - Yuto Abe
- Department of Applied Physics, National Defense Academy, 1-10-20 Hashirimizu, Yokosuka, 239-8686, Japan
| | - Shinya Genda
- Department of Applied Physics, National Defense Academy, 1-10-20 Hashirimizu, Yokosuka, 239-8686, Japan
| | - Takashi Honda
- Zeon Corporation, 1-2-1 Yako, Kawasaki-ku, Kawasaki, 210-9507, Japan
| |
Collapse
|
8
|
Wei T, Bao L, Hauke F, Hirsch A. Recent Advances in Graphene Patterning. Chempluschem 2020; 85:1655-1668. [PMID: 32757359 DOI: 10.1002/cplu.202000419] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/08/2020] [Indexed: 02/04/2023]
Abstract
As an emerging field of research, graphene patterning has received considerable attention because of its ability to tailor the structure of graphene and the respective properties, aiming at practical applications such as electronic devices, catalysts, and sensors. Recent efforts in this field have led to the development of a variety of different approaches to pattern graphene sheets, providing a multitude of graphene patterns with different shapes and sizes. These established patterning techniques in combination with graphene chemistry have paved the road towards highly attractive chemical patterning approaches, establishing a very promising and vigorously developing research topic. In this review, an overview of commonly used strategies is presented that are categorized into top-down and bottom-up routes for graphene patterning, focusing mainly on new advances. Other than the introduction of basic concepts of each method, the advantages/disadvantages are compared as well. In addition, for the first time, an overview of chemical patterning techniques is outlined. At the end, the challenges and future perspectives in the field are envisioned.
Collapse
Affiliation(s)
- Tao Wei
- Department of Chemistry and Pharmacy & Joint Institute of Advance Materials and Processes (ZMP), Friedrich-Alexander University of Erlangen-Nürnberg, Nikolaus-Fiebiger-Strasse 10, 91058, Erlangen, Germany
| | - Lipiao Bao
- Department of Chemistry and Pharmacy & Joint Institute of Advance Materials and Processes (ZMP), Friedrich-Alexander University of Erlangen-Nürnberg, Nikolaus-Fiebiger-Strasse 10, 91058, Erlangen, Germany
| | - Frank Hauke
- Department of Chemistry and Pharmacy & Joint Institute of Advance Materials and Processes (ZMP), Friedrich-Alexander University of Erlangen-Nürnberg, Nikolaus-Fiebiger-Strasse 10, 91058, Erlangen, Germany
| | - Andreas Hirsch
- Department of Chemistry and Pharmacy & Joint Institute of Advance Materials and Processes (ZMP), Friedrich-Alexander University of Erlangen-Nürnberg, Nikolaus-Fiebiger-Strasse 10, 91058, Erlangen, Germany
| |
Collapse
|
9
|
Tharmavaram M, Rawtani D, Pandey G. Fabrication routes for one-dimensional nanostructures via block copolymers. NANO CONVERGENCE 2017; 4:12. [PMID: 28546902 PMCID: PMC5423919 DOI: 10.1186/s40580-017-0106-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Accepted: 04/17/2017] [Indexed: 06/07/2023]
Abstract
Nanotechnology is the field which deals with fabrication of materials with dimensions in the nanometer range by manipulating atoms and molecules. Various synthesis routes exist for the one, two and three dimensional nanostructures. Recent advancements in nanotechnology have enabled the usage of block copolymers for the synthesis of such nanostructures. Block copolymers are versatile polymers with unique properties and come in many types and shapes. Their properties are highly dependent on the blocks of the copolymers, thus allowing easy tunability of its properties. This review briefly focusses on the use of block copolymers for synthesizing one-dimensional nanostructures especially nanowires, nanorods, nanoribbons and nanofibers. Template based, lithographic, and solution based approaches are common approaches in the synthesis of nanowires, nanorods, nanoribbons, and nanofibers. Synthesis of metal, metal oxides, metal oxalates, polymer, and graphene one dimensional nanostructures using block copolymers have been discussed as well.
Collapse
Affiliation(s)
- Maithri Tharmavaram
- Institute of Research & Development, Gujarat Forensic Sciences University, Sector 18-A, Near Police Bhavan, Gandhinagar, Gujarat 382007 India
| | - Deepak Rawtani
- Institute of Research & Development, Gujarat Forensic Sciences University, Sector 18-A, Near Police Bhavan, Gandhinagar, Gujarat 382007 India
| | - Gaurav Pandey
- Institute of Research & Development, Gujarat Forensic Sciences University, Sector 18-A, Near Police Bhavan, Gandhinagar, Gujarat 382007 India
| |
Collapse
|
10
|
Tang GP, Zhang ZH, Deng XQ, Fan ZQ, Zhang H, Sun L. The effect of different hydrogen terminations on the structural and electronic properties in the triangular array graphene nanomeshes. RSC Adv 2017. [DOI: 10.1039/c6ra27465j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Constructing periodic nanoscale holes on graphene to form graphene nanomeshes (GNMs) is an effective way for opening band gaps. The GNMs terminated by di-hydrogenation could open a sizable band gap due to the stronger on-site potential between holes.
Collapse
Affiliation(s)
- G. P. Tang
- Institute of Nanomaterial and Nanostructure
- Changsha University of Science & Technology
- Changsha 410114
- China
| | - Z. H. Zhang
- Institute of Nanomaterial and Nanostructure
- Changsha University of Science & Technology
- Changsha 410114
- China
| | - X. Q. Deng
- Institute of Nanomaterial and Nanostructure
- Changsha University of Science & Technology
- Changsha 410114
- China
| | - Z. Q. Fan
- Institute of Nanomaterial and Nanostructure
- Changsha University of Science & Technology
- Changsha 410114
- China
| | - H. L. Zhang
- Institute of Nanomaterial and Nanostructure
- Changsha University of Science & Technology
- Changsha 410114
- China
| | - L. Sun
- Institute of Nanomaterial and Nanostructure
- Changsha University of Science & Technology
- Changsha 410114
- China
| |
Collapse
|
11
|
Wang Z, Li T, Schulte L, Almdal K, Ndoni S. Photocatalytic Nanostructuring of Graphene Guided by Block Copolymer Self-Assembly. ACS APPLIED MATERIALS & INTERFACES 2016; 8:8329-8334. [PMID: 26999508 DOI: 10.1021/acsami.6b01021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Nanostructured graphene exhibits many intriguing properties. For example, precisely controlled graphene nanomeshes can be applied in electronic, photonic, or sensing devices. However, fabrication of nanopatterned graphene with periodic supperlattice remains a challenge. In this work, periodic graphene nanomesh was fabricated by photocatalysis of single-layer graphene suspended on top of TiO2-covered nanopillars, which were produced by combining block copolymer nanolithography with atomic layer deposition. Graphene nanoribbons were also prepared by the same method applied to a line-forming block copolymer template. This mask-free and nonchemical/nonplasma route offers an exciting platform for nanopatterning of graphene and other UV-transparent materials for device engineering.
Collapse
Affiliation(s)
- Zhongli Wang
- Department of Micro- and Nanotechnology and ‡Center for Nanostructured Graphene, Technical University of Denmark , 2800 Konegs Lyngby, Denmark
| | - Tao Li
- Department of Micro- and Nanotechnology and ‡Center for Nanostructured Graphene, Technical University of Denmark , 2800 Konegs Lyngby, Denmark
| | - Lars Schulte
- Department of Micro- and Nanotechnology and ‡Center for Nanostructured Graphene, Technical University of Denmark , 2800 Konegs Lyngby, Denmark
| | - Kristoffer Almdal
- Department of Micro- and Nanotechnology and ‡Center for Nanostructured Graphene, Technical University of Denmark , 2800 Konegs Lyngby, Denmark
| | - Sokol Ndoni
- Department of Micro- and Nanotechnology and ‡Center for Nanostructured Graphene, Technical University of Denmark , 2800 Konegs Lyngby, Denmark
| |
Collapse
|