1
|
Raja SN, Jain S, Kipen J, Jaldén J, Stemme G, Herland A, Niklaus F. Electromigrated Gold Nanogap Tunnel Junction Arrays: Fabrication and Electrical Behavior in Liquid and Gaseous Media. ACS APPLIED MATERIALS & INTERFACES 2024; 16:37131-37146. [PMID: 38954436 PMCID: PMC11261569 DOI: 10.1021/acsami.4c03282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 06/19/2024] [Accepted: 06/19/2024] [Indexed: 07/04/2024]
Abstract
Tunnel junctions have been suggested as high-throughput electronic single molecule sensors in liquids with several seminal experiments conducted using break junctions with reconfigurable gaps. For practical single molecule sensing applications, arrays of on-chip integrated fixed-gap tunnel junctions that can be built into compact systems are preferable. Fabricating nanogaps by electromigration is one of the most promising approaches to realize on-chip integrated tunnel junction sensors. However, the electrical behavior of fixed-gap tunnel junctions immersed in liquid media has not been systematically studied to date, and the formation of electromigrated nanogap tunnel junctions in liquid media has not yet been demonstrated. In this work, we perform a comparative study of the formation and electrical behavior of arrays of gold nanogap tunnel junctions made by feedback-controlled electromigration immersed in various liquid and gaseous media (deionized water, mesitylene, ethanol, nitrogen, and air). We demonstrate that tunnel junctions can be obtained from microfabricated gold nanoconstrictions inside liquid media. Electromigration of junctions in air produces the highest yield (61-67%), electromigration in deionized water and mesitylene results in a lower yield than in air (44-48%), whereas electromigration in ethanol fails to produce viable tunnel junctions due to interfering electrochemical processes. We map out the stability of the conductance characteristics of the resulting tunnel junctions and identify medium-specific operational conditions that have an impact on the yield of forming stable junctions. Furthermore, we highlight the unique challenges associated with working with arrays of large numbers of tunnel junctions in batches. Our findings will inform future efforts to build single molecule sensors using on-chip integrated tunnel junctions.
Collapse
Affiliation(s)
- Shyamprasad N. Raja
- Division
of Micro and Nanosystems (MST), School of Electrical Engineering and
Computer Science (EECS), KTH Royal Institute
of Technology, SE-10044 Stockholm, Sweden
| | - Saumey Jain
- Division
of Micro and Nanosystems (MST), School of Electrical Engineering and
Computer Science (EECS), KTH Royal Institute
of Technology, SE-10044 Stockholm, Sweden
- Division
of Nanobiotechnology, SciLifeLab, Department of Protein Science, School
of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Javier Kipen
- Division
of Information Science and Engineering (ISE), School of Electrical
Engineering and Computer Science (EECS), KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Joakim Jaldén
- Division
of Information Science and Engineering (ISE), School of Electrical
Engineering and Computer Science (EECS), KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Göran Stemme
- Division
of Micro and Nanosystems (MST), School of Electrical Engineering and
Computer Science (EECS), KTH Royal Institute
of Technology, SE-10044 Stockholm, Sweden
| | - Anna Herland
- Division
of Nanobiotechnology, SciLifeLab, Department of Protein Science, School
of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
- AIMES-Center
for the Advancement of Integrated Medical and Engineering Sciences,
Department of Neuroscience, Karolinska Institute, SE-17177 Solna, Sweden
| | - Frank Niklaus
- Division
of Micro and Nanosystems (MST), School of Electrical Engineering and
Computer Science (EECS), KTH Royal Institute
of Technology, SE-10044 Stockholm, Sweden
| |
Collapse
|
2
|
Li T, Bandari VK, Schmidt OG. Molecular Electronics: Creating and Bridging Molecular Junctions and Promoting Its Commercialization. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2209088. [PMID: 36512432 DOI: 10.1002/adma.202209088] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 11/28/2022] [Indexed: 06/02/2023]
Abstract
Molecular electronics is driven by the dream of expanding Moore's law to the molecular level for next-generation electronics through incorporating individual or ensemble molecules into electronic circuits. For nearly 50 years, numerous efforts have been made to explore the intrinsic properties of molecules and develop diverse fascinating molecular electronic devices with the desired functionalities. The flourishing of molecular electronics is inseparable from the development of various elegant methodologies for creating nanogap electrodes and bridging the nanogap with molecules. This review first focuses on the techniques for making lateral and vertical nanogap electrodes by breaking, narrowing, and fixed modes, and highlights their capabilities, applications, merits, and shortcomings. After summarizing the approaches of growing single molecules or molecular layers on the electrodes, the methods of constructing a complete molecular circuit are comprehensively grouped into three categories: 1) directly bridging one-molecule-electrode component with another electrode, 2) physically bridging two-molecule-electrode components, and 3) chemically bridging two-molecule-electrode components. Finally, the current state of molecular circuit integration and commercialization is discussed and perspectives are provided, hoping to encourage the community to accelerate the realization of fully scalable molecular electronics for a new era of integrated microsystems and applications.
Collapse
Affiliation(s)
- Tianming Li
- Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany
- Material Systems for Nanoelectronics, Chemnitz University of Technology, 09111, Chemnitz, Germany
| | - Vineeth Kumar Bandari
- Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany
- Material Systems for Nanoelectronics, Chemnitz University of Technology, 09111, Chemnitz, Germany
| | - Oliver G Schmidt
- Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany
- Material Systems for Nanoelectronics, Chemnitz University of Technology, 09111, Chemnitz, Germany
- Nanophysics, Dresden University of Technology, 01069, Dresden, Germany
| |
Collapse
|
3
|
Hu KJ, Yan W, Zhang M, Song F. Electrical devices designed based on inorganic clusters. NANOTECHNOLOGY 2022; 33:502001. [PMID: 36063786 DOI: 10.1088/1361-6528/ac8f4e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Accepted: 09/04/2022] [Indexed: 06/15/2023]
Abstract
The idea of exploring the bottom brink of material science has been carried out for more than two decades. Clusters science is the frontmost study of all nanoscale structures. Being an example of 0-dimensional quantum dot, nanocluster serves as the bridge between atomic and conventionally understood solid-state physics. The forming mechanism of clusters is found to be the mutual effects of electronic and geometric configuration. It is found that electronic shell structure influences the properties and geometric structure of the cluster until its size becomes larger, where electronic effects submerge in geometric structure. The discrete electronic structures depend on the size and conformation of clusters, which can be controlled artificially for potential device applications. Especially, small clusters with a size of 1-2 nm, whose electronic states are possibly discrete enough to overcome thermal fluctuations, are expected to build a single-electron transistor with room temperature operation. However, exciting as the progress may be seen, cluster science still falls within the territory of merely the extension of atomic and molecular science. Its production rate limits the scientific and potential application research of nanoclusters. It is suggested in this review that the mass-produce ability without losing the atomic precision selectivity would be the milestone for nanoclusters to advance to material science.
Collapse
Affiliation(s)
- Kuo-Juei Hu
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, Jiangsu, People's Republic of China
| | - Weicheng Yan
- College of Integrated Circuit Science and Engineering, Nanjing University of Posts and Telecommunications, 210023, Qixia District, Nanjing 210023, Jiangsu, People's Republic of China
| | - Minhao Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, Jiangsu, People's Republic of China
| | - Fengqi Song
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, Jiangsu, People's Republic of China
| |
Collapse
|
4
|
Luo S, Mancini A, Wang F, Liu J, Maier SA, de Mello JC. High-Throughput Fabrication of Triangular Nanogap Arrays for Surface-Enhanced Raman Spectroscopy. ACS NANO 2022; 16:7438-7447. [PMID: 35381178 PMCID: PMC9134500 DOI: 10.1021/acsnano.1c09930] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 04/01/2022] [Indexed: 05/31/2023]
Abstract
Squeezing light into nanometer-sized metallic nanogaps can generate extremely high near-field intensities, resulting in dramatically enhanced absorption, emission, and Raman scattering of target molecules embedded within the gaps. However, the scarcity of low-cost, high-throughput, and reproducible nanogap fabrication methods offering precise control over the gap size is a continuing obstacle to practical applications. Using a combination of molecular self-assembly, colloidal nanosphere lithography, and physical peeling, we report here a high-throughput method for fabricating large-area arrays of triangular nanogaps that allow the gap width to be tuned from ∼10 to ∼3 nm. The nanogap arrays function as high-performance substrates for surface-enhanced Raman spectroscopy (SERS), with measured enhancement factors as high as 108 relative to a thin gold film. Using the nanogap arrays, methylene blue dye molecules can be detected at concentrations as low as 1 pM, while adenine biomolecules can be detected down to 100 pM. We further show that it is possible to achieve sensitive SERS detection on binary-metal nanogap arrays containing gold and platinum, potentially extending SERS detection to the investigation of reactive species at platinum-based catalytic and electrochemical surfaces.
Collapse
Affiliation(s)
- Sihai Luo
- Department
of Chemistry, Norwegian University of Science
and Technology (NTNU), 7491 Trondheim, Norway
| | - Andrea Mancini
- Chair
in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maximilians-Universität München, Königinstrasse 10, 80539 München, Germany
| | - Feng Wang
- Department
of Structural Engineering, Norwegian University
of Science and Technology (NTNU), Trondheim 7491, Norway
| | - Junyang Liu
- College
of Chemistry and Chemical Engineering, Xiamen
University, Xiamen 361005, China
| | - Stefan A. Maier
- Chair
in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maximilians-Universität München, Königinstrasse 10, 80539 München, Germany
- Blackett
Laboratory, Imperial College London, Prince Consort Road, London SW7 2BZ, United Kingdom
| | - John C. de Mello
- Department
of Chemistry, Norwegian University of Science
and Technology (NTNU), 7491 Trondheim, Norway
| |
Collapse
|
5
|
Flexible Sensory Systems: Structural Approaches. Polymers (Basel) 2022; 14:polym14061232. [PMID: 35335562 PMCID: PMC8955130 DOI: 10.3390/polym14061232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/14/2022] [Accepted: 03/14/2022] [Indexed: 11/25/2022] Open
Abstract
Biology is characterized by smooth, elastic, and nonplanar surfaces; as a consequence, soft electronics that enable interfacing with nonplanar surfaces allow applications that could not be achieved with the rigid and integrated circuits that exist today. Here, we review the latest examples of technologies and methods that can replace elasticity through a structural approach; these approaches can modify mechanical properties, thereby improving performance, while maintaining the existing material integrity. Furthermore, an overview of the recent progress in wave/wrinkle, stretchable interconnect, origami/kirigami, crack, nano/micro, and textile structures is provided. Finally, potential applications and expected developments in soft electronics are discussed.
Collapse
|
6
|
Zhao Q, Yang H, Nie B, Luo Y, Shao J, Li G. Wafer-Scale and Cost-Effective Manufacturing of Controllable Nanogap Arrays for Highly Sensitive SERS Sensing. ACS APPLIED MATERIALS & INTERFACES 2022; 14:3580-3590. [PMID: 34983178 DOI: 10.1021/acsami.1c22465] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The metallic nanogap has been proved as an efficient architecture for surface-enhanced Raman scattering (SERS) applications. Although a lot of nanogap fabrication methods have been proposed in the last few decades, the economical and high-yield manufacturing of sub-10 nm gaps remains a challenge. Here, we present a convenient and cost-effective fabrication method for wafer-scale patterning of metallic nanogaps, which simply combines photolithographic metal patterning, swelling-induced nanocracking, and superimposition metal sputtering without requiring expensive nanofabrication equipment. By controlling the swelling time and metal deposition thickness, the gap size can be precisely defined, down to the sub-10 nm scale. Furthermore, we demonstrate that the fabricated nanogap array can be used as an excellent SERS substrate for molecule measurements and shows a high Raman enhancement factor of ∼108 and a high sensitivity for the detection of rhodamine 6G (R6G) molecules, even down to 10-14 M, indicating an extraordinary capability for single-molecule detection. Due to its high controllability and wafer-scale fabrication capability, this nanogap fabrication method offers a promising route for highly sensitive and economical SERS detections.
Collapse
Affiliation(s)
- Qiang Zhao
- Key Laboratory of Optoelectronic Technology and Systems, Ministry of Education, Defense Key Disciplines Lab of Novel Micro-Nano Devices and System Technology, Chongqing University, Chongqing 400044, China
- Micro-/Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Huan Yang
- Micro-/Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Bangbang Nie
- Micro-/Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Yongsong Luo
- Micro-/Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Jinyou Shao
- Micro-/Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Gang Li
- Key Laboratory of Optoelectronic Technology and Systems, Ministry of Education, Defense Key Disciplines Lab of Novel Micro-Nano Devices and System Technology, Chongqing University, Chongqing 400044, China
| |
Collapse
|
7
|
Luo S, Hoff BH, Maier SA, de Mello JC. Scalable Fabrication of Metallic Nanogaps at the Sub-10 nm Level. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2102756. [PMID: 34719889 PMCID: PMC8693066 DOI: 10.1002/advs.202102756] [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: 06/29/2021] [Revised: 08/09/2021] [Indexed: 06/01/2023]
Abstract
Metallic nanogaps with metal-metal separations of less than 10 nm have many applications in nanoscale photonics and electronics. However, their fabrication remains a considerable challenge, especially for applications that require patterning of nanoscale features over macroscopic length-scales. Here, some of the most promising techniques for nanogap fabrication are evaluated, covering established technologies such as photolithography, electron-beam lithography (EBL), and focused ion beam (FIB) milling, plus a number of newer methods that use novel electrochemical and mechanical means to effect the patterning. The physical principles behind each method are reviewed and their strengths and limitations for nanogap patterning in terms of resolution, fidelity, speed, ease of implementation, versatility, and scalability to large substrate sizes are discussed.
Collapse
Affiliation(s)
- Sihai Luo
- Department of ChemistryNorwegian University of Science and Technology (NTNU)TrondheimNO‐7491Norway
| | - Bård H. Hoff
- Department of ChemistryNorwegian University of Science and Technology (NTNU)TrondheimNO‐7491Norway
| | - Stefan A. Maier
- Nano‐Institute MunichFaculty of PhysicsLudwig‐Maximilians‐Universität MünchenMünchen80539Germany
- Blackett LaboratoryDepartment of PhysicsImperial College LondonLondonSW7 2AZUK
| | - John C. de Mello
- Department of ChemistryNorwegian University of Science and Technology (NTNU)TrondheimNO‐7491Norway
| |
Collapse
|
8
|
Li N, Zhang B, He Y, Luo Y. Sub-Picosecond Nanodiodes for Low-Power Ultrafast Electronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2100874. [PMID: 34245057 DOI: 10.1002/adma.202100874] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 04/27/2021] [Indexed: 06/13/2023]
Abstract
The tradeoff between ultrahigh speed and low power is a dominant challenge in continuously improving modern electronics. Fundamental electronic devices with ultrafast response are highly desired in low-power electronics. However, conventional semiconductor electronic devices now near the speed limit from the physical roadblocks including short-channel effect, restricted carrier velocity, and heat death. Currently emerging electronic devices also face formidable difficulties to achieve high-speed performance at low operating voltage without heat disturbance. Here, a novel fabricated coplanar tip-to-edge semiconductor-free nanostructure with asymmetric sub-10 nm air channel is reported, stimulating electric-field accelerated scattering-free transport of electrons and resulting in ultrafast response of record sub-picoseconds at a low turn-on voltage around 0.7 V. Simulation results show a typical electrical response down to 64 fs, which is ≈103 times faster than that of conventional semiconductor electronic devices. The coplanar asymmetric nanostructure allows a high rectifying ratio up to 106 which is superior to that of the most promising 2D semiconducting nanodiodes. In addition, heat death is overcome due to the inherent advantages from the novel nanostructure and underlying working mechanism. The intriguing nanodiodes will attract broadly interests in electronics due to their potential as rudimentary building blocks in ultrafast electronic integrated circuits.
Collapse
Affiliation(s)
- Nannan Li
- Micro/Nano Fabrication Laboratory (MNFL), Microsystem and Terahertz Research Center, CAEP, Chengdu, 610200, China
- Institute of Electronic Engineering, CAEP, Mianyang, 621900, China
| | - Binglei Zhang
- Micro/Nano Fabrication Laboratory (MNFL), Microsystem and Terahertz Research Center, CAEP, Chengdu, 610200, China
- Institute of Electronic Engineering, CAEP, Mianyang, 621900, China
| | - Yue He
- Institute of Electronic Engineering, CAEP, Mianyang, 621900, China
- Terahertz Communication and Radar Technology Research Laboratory, Microsystem and Terahertz Research Center, CAEP, Chengdu, 610200, China
| | - Yi Luo
- Micro/Nano Fabrication Laboratory (MNFL), Microsystem and Terahertz Research Center, CAEP, Chengdu, 610200, China
| |
Collapse
|
9
|
Zhou S, Li X, Huang J, Wang Z, Liu Y, Gao S, Xu Z, Jiang L. Fabrication of nanogap structures through spatially shaped femtosecond laser modification with the assistance of wet chemical etching. OPTICS LETTERS 2021; 46:3560-3563. [PMID: 34329224 DOI: 10.1364/ol.431385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 06/23/2021] [Indexed: 06/13/2023]
Abstract
Fabricating nanostructures with an extremely small feature size through a near-infrared femtosecond laser is a considerable challenge. In this Letter, we report a flexible, facile, and mask-free method that enables the formation of nanogap structures with a controllable size on silicon. This method involves spatially shaped femtosecond laser single-pulse modification assisted with chemical etching. Nanogaps obtained after etching can be divided into two categories, namely a ring dimer with a nanogap (type I) and Crack-nanogap (type II). The nanogap between the ring dimer could be reduced to 68 nm with a gradual increase in the laser fluence. For the Crack-nanogap obtained through crack propagation induced by stress release during a wet etching process, the smallest gap size is approximately 9 nm.
Collapse
|
10
|
Kim T, Kim D, Yoon J, Joo Y, Hong Y. Stamp-Perforation-Inspired Micronotch for Selectively Tearing Fiber-Bridged Carbon Nanotube Thin Films and Its Applications for Strain Classification. ACS APPLIED MATERIALS & INTERFACES 2021; 13:32307-32315. [PMID: 34181397 DOI: 10.1021/acsami.1c08590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Cracks typically deteriorate the structural and electrical properties of materials when not properly controlled. A few papers recently reported the controlling methods of crack formation in the brittle materials utilizing the lateral V-notch structure. For ductile materials, however, there have been few papers reporting cracking phenomenon, but full cracking control including predesigned initiation, propagation, and termination has not been reported yet. Therefore, we report a predesigned full cracking control in ductile conductive carbon nanotube (CNT) films by introducing inkjet-printed L-shape micronotch (LMN) structures inspired by directional stamp perforation marks. In spite of the high fracture toughness of CNT films, the LMNs determine locations of initial crack formation and guide crack propagation in a predesigned way. Selective connection of isolated cracks in the CNT film increases its resistance monotonically under tensile strain and thus tremendously well maintains high linearity (adj. R2 value > 0.99) in resistance change over record large strain ranges of 0.01-100%, which enables us to quantitatively classify strain values accurately for previously reported practical body signals for the first time. We believe that our facile printing-based crack control strategy not only provides a comprehensive solution to various stretchable sensor applications but also builds a new milestone for cracking mechanism studies in fracture mechanics.
Collapse
Affiliation(s)
- Taehoon Kim
- Department of Electrical and Computer Engineering and Inter-University Semiconductor Research Center (ISRC), Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, South Korea
| | - Daesik Kim
- Department of Electrical and Computer Engineering and Inter-University Semiconductor Research Center (ISRC), Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, South Korea
| | - Jaeyoung Yoon
- Department of Electrical and Computer Engineering and Inter-University Semiconductor Research Center (ISRC), Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, South Korea
| | - Yunsik Joo
- Department of Electrical and Computer Engineering and Inter-University Semiconductor Research Center (ISRC), Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, South Korea
| | - Yongtaek Hong
- Department of Electrical and Computer Engineering and Inter-University Semiconductor Research Center (ISRC), Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, South Korea
| |
Collapse
|
11
|
Jung J, Kim KK, Suh YD, Hong S, Yeo J, Ko SH. Recent progress in controlled nano/micro cracking as an alternative nano-patterning method for functional applications. NANOSCALE HORIZONS 2020; 5:1036-1049. [PMID: 32469038 DOI: 10.1039/d0nh00241k] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Generally, cracking occurs for many reasons connected to uncertainties and to the non-uniformity resulting from intrinsic deficiencies in materials or the non-linearity of applied external (thermal, mechanical, etc.) stresses. However, recently, an increased level of effort has gone into analyzing the phenomenon of cracking and also into methods for controlling it. Sophisticated manipulation of cracking has yielded various cutting-edge technologies such as transparent conductors, mechanical sensors, microfluidics, and energy devices. In this paper, we present some of the recent progress that has been made in controlling cracking by giving an overview of the fabrication methods and working mechanisms used for various mediums. In addition, we discuss recent progress in the various applications of methods that use controlled cracking as an alternative to patterning tools.
Collapse
Affiliation(s)
- Jinwook Jung
- Applied Nano and Thermal Science Lab, Department of Mechanical Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.
| | | | | | | | | | | |
Collapse
|
12
|
Enrico A, Dubois V, Niklaus F, Stemme G. Scalable Manufacturing of Single Nanowire Devices Using Crack-Defined Shadow Mask Lithography. ACS APPLIED MATERIALS & INTERFACES 2019; 11:8217-8226. [PMID: 30698940 PMCID: PMC6426283 DOI: 10.1021/acsami.8b19410] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 01/30/2019] [Indexed: 05/08/2023]
Abstract
Single nanowires (NWs) have a broad range of applications in nanoelectronics, nanomechanics, and nanophotonics, but, to date, no technique can produce single sub-20 nm wide NWs with electrical connections in a scalable fashion. In this work, we combine conventional optical and crack lithographies to generate single NW devices with controllable and predictable dimensions and placement and with individual electrical contacts to the NWs. We demonstrate NWs made of gold, platinum, palladium, tungsten, tin, and metal oxides. We have used conventional i-line stepper lithography with a nominal resolution of 365 nm to define crack lithography structures in a shadow mask for large-scale manufacturing of sub-20 nm wide NWs, which is a 20-fold improvement over the resolution that is possible with the utilized stepper lithography. Overall, the proposed method represents an effective approach to generate single NW devices with useful applications in electrochemistry, photonics, and gas- and biosensing.
Collapse
Affiliation(s)
- Alessandro Enrico
- Department of Micro and Nanosystems, School of Electrical
Engineering and Computer Science, KTH Royal
Institute of Technology, SE-10044 Stockholm, Sweden
| | | | - Frank Niklaus
- Department of Micro and Nanosystems, School of Electrical
Engineering and Computer Science, KTH Royal
Institute of Technology, SE-10044 Stockholm, Sweden
| | - Göran Stemme
- Department of Micro and Nanosystems, School of Electrical
Engineering and Computer Science, KTH Royal
Institute of Technology, SE-10044 Stockholm, Sweden
| |
Collapse
|
13
|
Yang Y, Gu C, Li J. Sub-5 nm Metal Nanogaps: Physical Properties, Fabrication Methods, and Device Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1804177. [PMID: 30589217 DOI: 10.1002/smll.201804177] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 11/29/2018] [Indexed: 05/26/2023]
Abstract
Sub-5 nm metal nanogaps have attracted widespread attention in physics, chemistry, material sciences, and biology due to their physical properties, including great plasmon-enhanced effects in light-matter interactions and charge tunneling, Coulomb blockade, and the Kondo effect under an electrical stimulus. These properties especially meet the needs of many cutting-edge devices, such as sensing, optical, molecular, and electronic devices. However, fabricating sub-5 nm nanogaps is still challenging at the present, and scaled and reliable fabrication, improved addressability, and multifunction integration are desired for further applications in commercial devices. The aim of this work is to provide a comprehensive overview of sub-5 nm nanogaps and to present recent advancements in metal nanogaps, including their physical properties, fabrication methods, and device applications, with the ultimate aim to further inspire scientists and engineers in their research.
Collapse
Affiliation(s)
- Yang Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Changzhi Gu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Junjie Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| |
Collapse
|
14
|
Eklöf-Österberg J, Gschneidtner T, Tebikachew B, Lara-Avila S, Moth-Poulsen K. Parallel Fabrication of Self-Assembled Nanogaps for Molecular Electronic Devices. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1803471. [PMID: 30358919 DOI: 10.1002/smll.201803471] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 10/04/2018] [Indexed: 06/08/2023]
Abstract
Single molecule electronics might be a way to add additional function to nanoscale devices and continue miniaturization beyond current state of the art. Here, a combined top-down and bottom-up strategy is employed to assemble single molecules onto prefabricated electrodes. Protodevices, which are self-assembled nanogaps composed by two gold nanoparticles linked by a single or a few molecules, are guided onto top-down prefabricated nanosized nickel electrodes with sandwiched palladium layers. It is shown that an optimized geometry of multilayered metallic (top-down) electrodes facilitates the assembly of (bottom-up) nanostructures by surface charge interactions. Moreover, such assembly process results in an electrode-nanoparticle interface free from linking molecules that enable electrical measurements to probe electron transport properties of the nanoparticle-molecule-nanoparticle protodevices.
Collapse
Affiliation(s)
- Johnas Eklöf-Österberg
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, 412 96, Sweden
| | - Tina Gschneidtner
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, 412 96, Sweden
| | - Behabitu Tebikachew
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, 412 96, Sweden
| | - Samuel Lara-Avila
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, Gothenburg, 412 96, Sweden
- National Physical Laboratory, Teddington, TW11 0LW, UK
| | - Kasper Moth-Poulsen
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, 412 96, Sweden
| |
Collapse
|
15
|
Dubois V, Bleiker SJ, Stemme G, Niklaus F. Scalable Manufacturing of Nanogaps. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1801124. [PMID: 30156331 DOI: 10.1002/adma.201801124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/23/2018] [Indexed: 05/24/2023]
Abstract
The ability to manufacture a nanogap in between two electrodes has proven a powerful catalyst for scientific discoveries in nanoscience and molecular electronics. A wide range of bottom-up and top-down methodologies are now available to fabricate nanogaps that are less than 10 nm wide. However, most available techniques involve time-consuming serial processes that are not compatible with large-scale manufacturing of nanogap devices. The scalable manufacturing of sub-10 nm gaps remains a great technological challenge that currently hinders both experimental nanoscience and the prospects for commercial exploitation of nanogap devices. Here, available nanogap fabrication methodologies are reviewed and a detailed comparison of their merits is provided, with special focus on large-scale and reproducible manufacturing of nanogaps. The most promising approaches that could achieve a breakthrough in research and commercial applications are identified. Emerging scalable nanogap manufacturing methodologies will ultimately enable applications with high scientific and societal impact, including high-speed whole genome sequencing, electromechanical computing, and molecular electronics using nanogap electrodes.
Collapse
Affiliation(s)
- Valentin Dubois
- Department of Micro and Nano Systems, KTH Royal Institute of Technology, 100 44, Stockholm, Sweden
| | - Simon J Bleiker
- Department of Micro and Nano Systems, KTH Royal Institute of Technology, 100 44, Stockholm, Sweden
| | - Göran Stemme
- Department of Micro and Nano Systems, KTH Royal Institute of Technology, 100 44, Stockholm, Sweden
| | - Frank Niklaus
- Department of Micro and Nano Systems, KTH Royal Institute of Technology, 100 44, Stockholm, Sweden
| |
Collapse
|
16
|
Dubois V, Raja SN, Gehring P, Caneva S, van der Zant HSJ, Niklaus F, Stemme G. Massively parallel fabrication of crack-defined gold break junctions featuring sub-3 nm gaps for molecular devices. Nat Commun 2018; 9:3433. [PMID: 30143636 PMCID: PMC6109151 DOI: 10.1038/s41467-018-05785-2] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 07/25/2018] [Indexed: 11/08/2022] Open
Abstract
Break junctions provide tip-shaped contact electrodes that are fundamental components of nano and molecular electronics. However, the fabrication of break junctions remains notoriously time-consuming and difficult to parallelize. Here we demonstrate true parallel fabrication of gold break junctions featuring sub-3 nm gaps on the wafer-scale, by relying on a novel self-breaking mechanism based on controlled crack formation in notched bridge structures. We achieve fabrication densities as high as 7 million junctions per cm2, with fabrication yields of around 7% for obtaining crack-defined break junctions with sub-3 nm gaps of fixed gap width that exhibit electron tunneling. We also form molecular junctions using dithiol-terminated oligo(phenylene ethynylene) (OPE3) to demonstrate the feasibility of our approach for electrical probing of molecules down to liquid helium temperatures. Our technology opens a whole new range of experimental opportunities for nano and molecular electronics applications, by enabling very large-scale fabrication of solid-state break junctions.
Collapse
Affiliation(s)
- Valentin Dubois
- Department of Micro and Nanosystems (MST), School of Electrical Engineering and Computer Science (EECS), KTH Royal Institute of Technology, SE-10044, Stockholm, Sweden
| | - Shyamprasad N Raja
- Department of Micro and Nanosystems (MST), School of Electrical Engineering and Computer Science (EECS), KTH Royal Institute of Technology, SE-10044, Stockholm, Sweden
| | - Pascal Gehring
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands
| | - Sabina Caneva
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands
| | - Herre S J van der Zant
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands
| | - Frank Niklaus
- Department of Micro and Nanosystems (MST), School of Electrical Engineering and Computer Science (EECS), KTH Royal Institute of Technology, SE-10044, Stockholm, Sweden.
| | - Göran Stemme
- Department of Micro and Nanosystems (MST), School of Electrical Engineering and Computer Science (EECS), KTH Royal Institute of Technology, SE-10044, Stockholm, Sweden.
| |
Collapse
|
17
|
Chen Y, Guo Q, Huang G, Li G, Wang L, Tian Z, Qin Y, Di Z, Mei Y. Multifunctional Nanocracks in Silicon Nanomembranes by Notch-Assisted Transfer Printing. ACS APPLIED MATERIALS & INTERFACES 2018; 10:25644-25651. [PMID: 29992807 DOI: 10.1021/acsami.8b06962] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Manipulating nanocracks to produce various nanodevices has attracted increasing interest. Here, based on the mature transfer printing technique, a novel notch-assisted transfer printing technique was engaged to produce nanocracks by simply introducing notch structures into the transferred nanomembranes. Both experiments and finite element simulations were used to elucidate the probability of nanocrack formation during the transfer process, and the results demonstrated that the geometry of nanomembranes played a key role in concentrating stress and producing nanocracks. We further demonstrated that the obtained nanocrack can be used as a surface-enhanced Raman scattering substrate because of the significant enhancement of electric fields. In addition, the capillary condensation of water molecules in the nanocrack led to an obvious change of resistance, thus providing an opportunity for the crack-based structure to be used as an ultrasensitive humidity sensor. The current approach can be applied to producing nanocracks from multiple materials and will have important applications in the field of nanodevices.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Zengfeng Di
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology , Chinese Academy of Sciences , Shanghai 200050 , People's Republic of China
| | | |
Collapse
|
18
|
Cai H, Meng Q, Zhao H, Li M, Dai Y, Lin Y, Ding H, Pan N, Tian Y, Luo Y, Wang X. High-Throughput Fabrication of Ultradense Annular Nanogap Arrays for Plasmon-Enhanced Spectroscopy. ACS APPLIED MATERIALS & INTERFACES 2018; 10:20189-20195. [PMID: 29799180 DOI: 10.1021/acsami.8b04810] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The confinement of light into nanometer-sized metallic nanogaps can lead to an extremely high field enhancement, resulting in dramatically enhanced absorption, emission, and surface-enhanced Raman scattering (SERS) of molecules embedded in nanogaps. However, low-cost, high-throughput, and reliable fabrication of ultra-high-dense nanogap arrays with precise control of the gap size still remains a challenge. Here, by combining colloidal lithography and atomic layer deposition technique, a reproducible method for fabricating ultra-high-dense arrays of hexagonal close-packed annular nanogaps over large areas is demonstrated. The annular nanogap arrays with a minimum diameter smaller than 100 nm and sub-1 nm gap width have been produced, showing excellent SERS performance with a typical enhancement factor up to 3.1 × 106 and a detection limit of 10-11 M. Moreover, it can also work as a high-quality field enhancement substrate for studying two-dimensional materials, such as MoSe2. Our method provides an attractive approach to produce controllable nanogaps for enhanced light-matter interaction at the nanoscale.
Collapse
Affiliation(s)
| | | | | | | | - Yanmeng Dai
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering , Shenzhen University , Shenzhen 518060 , China
| | | | | | | | - Yangchao Tian
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230027 , China
| | | | | |
Collapse
|
19
|
Pan R, Yang Y, Wang Y, Li S, Liu Z, Su Y, Quan B, Li Y, Gu C, Li J. Nanocracking and metallization doubly defined large-scale 3D plasmonic sub-10 nm-gap arrays as extremely sensitive SERS substrates. NANOSCALE 2018; 10:3171-3180. [PMID: 29364303 DOI: 10.1039/c7nr08646f] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Considering the technological difficulties in the existing approaches to form nanoscale gaps, a convenient method to fabricate three-dimensional (3D) sub-10 nm Ag/SiNx gap arrays has been demonstrated in this study, controlled by a combination of stress-induced nanocracking of a SiNx nanobridge and Ag nanofilm deposition. This scalable 3D plasmonic nanogap is specially suspended above a substrate, having a tunable nanogap width and large height-to-width ratio to form a nanocavity underneath. As a surface-enhanced Raman scattering (SERS) substrate, the 3D Ag/SiNx nanogap shows a large Raman enhancement factor of ∼108 and extremely high sensitivity for the detection of Rhodamine 6G (R6G) molecules, even down to 10-16 M, indicating an extraordinary capability for single-molecule detection. Further, we verified that the Fabry-Perot resonance occurred in the deep SiNx nanocavity under the Ag nanogap and contributed prominently to a tremendous enhancement of the local field in the Ag-nanogap zone and hence ultrasensitive SERS detection. This method circumvents the technological limitations to fabricate a sub-10 nm metal nanogap with unique features for wide applications in important scientific and technological areas.
Collapse
Affiliation(s)
- Ruhao Pan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Purohit G, Deepak, Katiyar M. Nanolithography using thermal stresses. RSC Adv 2018; 8:4928-4936. [PMID: 35539559 PMCID: PMC9077770 DOI: 10.1039/c8ra00278a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 01/11/2018] [Indexed: 11/21/2022] Open
Abstract
Nanometer separation (nanogap) in electrodes is a fundamental requirement for several nanoscale devices having applications in nanoelectronics, nanophotonics, biosensing, nanoporous filters, healthcare and medical diagnostics. Most nanolithography techniques, other than extreme/deep ultraviolet lithography are serial processes, such as e-beam lithography, and therefore not scalable. We demonstrate fabrication of nanogaps in Au electrodes over a large area/wafer in parallel processing mode resulting in high throughput. The proposed technique requires tools that are already available in a typical semiconductor device fabrication facility. The concept involves designing a ceramic/metal multilayer structure which is heated to bring the ceramic under tensile stress, and as a result it develops cracks due to low fracture toughness of the ceramic. The feasibility of this idea was established by calculating thermal stresses in different multilayers when heated to a specified temperature level. At practical temperatures, below 500 °C, the developed tensile stresses are higher than the critical stress needed for fracture. Subsequent to separation in the ceramic layer at the desired location, the underlying metal layer can be wet etched leading to separation in the metal also. For electrode fabrication, a predefined notch in the multilayer structure is used to obtain the nanogap at the desired location. For experimental validation, SiO x /Au/Ti layers on glass and silicon are patterned in I-shaped electrodes using conventional optical lithography. After vacuum annealing and etching, nanogaps in Au electrodes are simultaneously formed across a large area substrate/wafer. The nanoscale gaps formed in the Au electrodes were inspected using optical microscopy, FE-SEM imaging and finally were verified using an electrical isolation test. We achieved nanogaps with dimensions of ∼150-300 nm in Au electrodes on glass substrates.
Collapse
Affiliation(s)
- Gangadhar Purohit
- Materials Science & Engineering, Indian Institute of Technology Kanpur UP-208016 India
- National Centre for Flexible Electronics, Indian Institute of Technology Kanpur UP-208016 India
| | - Deepak
- Materials Science & Engineering, Indian Institute of Technology Kanpur UP-208016 India
- National Centre for Flexible Electronics, Indian Institute of Technology Kanpur UP-208016 India
| | - Monica Katiyar
- Materials Science & Engineering, Indian Institute of Technology Kanpur UP-208016 India
- National Centre for Flexible Electronics, Indian Institute of Technology Kanpur UP-208016 India
| |
Collapse
|
21
|
Samadi Khoshkhoo M, Maiti S, Schreiber F, Chassé T, Scheele M. Surface Functionalization with Copper Tetraaminophthalocyanine Enables Efficient Charge Transport in Indium Tin Oxide Nanocrystal Thin Films. ACS APPLIED MATERIALS & INTERFACES 2017; 9:14197-14206. [PMID: 28398030 DOI: 10.1021/acsami.7b00555] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Macroscopic superlattices of tin-doped indium oxide (ITO) nanocrystals (NCs) are prepared by self-assembly at the air/liquid interface followed by simultaneous ligand exchange with the organic semiconductor copper 4,4',4″,4‴-tetraaminophthalocyanine (Cu4APc). By using X-ray photoelectron spectroscopy (XPS), grazing-incidence small-angle X-ray scattering (GISAXS), and ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy, we demonstrate that the semiconductor molecules largely replace the native surfactant from the ITO NC surface and act as cross-linkers between neighboring particles. Transport measurements reveal an increase in electrical conductance by 9 orders of magnitude, suggesting that Cu4APc provides efficient electronic coupling for neighboring ITO NCs. This material provides the opportunity to study charge and spin transport through phthalocyanine monolayers.
Collapse
Affiliation(s)
- Mahdi Samadi Khoshkhoo
- Institute of Physical and Theoretical Chemistry, ‡Institute of Applied Physics, and §Center for Light-Matter Interaction, Sensors & Analytics LISA+, University of Tübingen , 72076 Tübingen, Germany
| | - Santanu Maiti
- Institute of Physical and Theoretical Chemistry, ‡Institute of Applied Physics, and §Center for Light-Matter Interaction, Sensors & Analytics LISA+, University of Tübingen , 72076 Tübingen, Germany
| | - Frank Schreiber
- Institute of Physical and Theoretical Chemistry, ‡Institute of Applied Physics, and §Center for Light-Matter Interaction, Sensors & Analytics LISA+, University of Tübingen , 72076 Tübingen, Germany
| | - Thomas Chassé
- Institute of Physical and Theoretical Chemistry, ‡Institute of Applied Physics, and §Center for Light-Matter Interaction, Sensors & Analytics LISA+, University of Tübingen , 72076 Tübingen, Germany
| | - Marcus Scheele
- Institute of Physical and Theoretical Chemistry, ‡Institute of Applied Physics, and §Center for Light-Matter Interaction, Sensors & Analytics LISA+, University of Tübingen , 72076 Tübingen, Germany
| |
Collapse
|
22
|
Dubois V, Niklaus F, Stemme G. Design and fabrication of crack-junctions. MICROSYSTEMS & NANOENGINEERING 2017; 3:17042. [PMID: 31057876 PMCID: PMC6444981 DOI: 10.1038/micronano.2017.42] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 06/01/2017] [Accepted: 06/19/2017] [Indexed: 05/06/2023]
Abstract
Nanogap electrodes consist of pairs of electrically conducting tips that exhibit nanoscale gaps. They are building blocks for a variety of applications in quantum electronics, nanophotonics, plasmonics, nanopore sequencing, molecular electronics, and molecular sensing. Crack-junctions (CJs) constitute a new class of nanogap electrodes that are formed by controlled fracture of suspended bridge structures fabricated in an electrically conducting thin film under residual tensile stress. Key advantages of the CJ methodology over alternative technologies are that CJs can be fabricated with wafer-scale processes, and that the width of each individual nanogap can be precisely controlled in a range from <2 to >100 nm. While the realization of CJs has been demonstrated in initial experiments, the impact of the different design parameters on the resulting CJs has not yet been studied. Here we investigate the influence of design parameters such as the dimensions and shape of the notches, the length of the electrode-bridge and the design of the anchors, on the formation and propagation of cracks and on the resulting features of the CJs. We verify that the design criteria yields accurate prediction of crack formation in electrode-bridges featuring a beam width of 280 nm and beam lengths ranging from 1 to 1.8 μm. We further present design as well as experimental guidelines for the fabrication of CJs and propose an approach to initiate crack formation after release etching of the suspended electrode-bridge, thereby enabling the realization of CJs with pristine electrode surfaces.
Collapse
Affiliation(s)
- Valentin Dubois
- KTH Royal Institute of Technology, Micro and Nanosystem, Osquldas väg 10, Stockholm 100 44, Sweden
| | - Frank Niklaus
- KTH Royal Institute of Technology, Micro and Nanosystem, Osquldas väg 10, Stockholm 100 44, Sweden
| | - Göran Stemme
- KTH Royal Institute of Technology, Micro and Nanosystem, Osquldas väg 10, Stockholm 100 44, Sweden
| |
Collapse
|