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Schels A, Herdl F, Hausladen M, Wohlfartsstätter D, Edler S, Bachmann M, Pahlke A, Schreiner R, Hansch W. Quantitative Field Emission Imaging for Studying the Doping-Dependent Emission Behavior of Silicon Field Emitter Arrays. MICROMACHINES 2023; 14:2008. [PMID: 38004864 PMCID: PMC10673020 DOI: 10.3390/mi14112008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 10/25/2023] [Accepted: 10/27/2023] [Indexed: 11/26/2023]
Abstract
Field emitter arrays (FEAs) are a promising component for novel vacuum micro- and nanoelectronic devices, such as microwave power amplifiers or fast-switching X-ray sources. However, the interrelated mechanisms responsible for FEA degradation and failure are not fully understood. Therefore, we present a measurement method for quantitative observation of individual emission sites during integral operation using a low-cost, commercially available CMOS imaging sensor. The emission and degradation behavior of three differently doped FEAs is investigated in current-regulated operation. The measurements reveal that the limited current of the p-doped emitters leads to an activation of up to 55% of the individual tips in the array, while the activation of the n-type FEA stopped at around 30%. This enhanced activation results in a more continuous and uniform current distribution for the p-type FEA. An analysis of the individual emitter characteristics before and after a constant current measurement provides novel perspectives on degradation behavior. A burn-in process that trims the emitting tips to an integral current-specific ideal field enhancement factor is observed. In this process, blunt tips are sharpened while sharp tips are dulled, resulting in homogenization within the FEA. The methodology is described in detail, making it easily adaptable for other groups to apply in the further development of promising FEAs.
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Affiliation(s)
- Andreas Schels
- Faculty of Electrical Engineering and Information Technology, University of the Bundeswehr Munich, 85577 Neubiberg, Germany; (F.H.)
| | - Florian Herdl
- Faculty of Electrical Engineering and Information Technology, University of the Bundeswehr Munich, 85577 Neubiberg, Germany; (F.H.)
| | - Matthias Hausladen
- Faculty of Applied Natural and Cultural Sciences, Ostbayerische Technische Hochschule Regensburg, 93053 Regensburg, Germany; (M.H.)
| | | | | | | | | | - Rupert Schreiner
- Faculty of Applied Natural and Cultural Sciences, Ostbayerische Technische Hochschule Regensburg, 93053 Regensburg, Germany; (M.H.)
| | - Walter Hansch
- Faculty of Electrical Engineering and Information Technology, University of the Bundeswehr Munich, 85577 Neubiberg, Germany; (F.H.)
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Go E, Kim JW, Lee JW, Ahn Y, Jeong JW, Kang JT, Park S, Yun KN, Kim SJ, Kim S, Yeon JH, Song YH. Enhanced interfacial reaction of silicon carbide fillers onto the metal substrate in carbon nanotube paste for reliable field electron emitters. NANOTECHNOLOGY 2021; 32:190001. [PMID: 33524956 DOI: 10.1088/1361-6528/abe1ef] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Adhesion of carbon nanotube (CNT) onto a cathode substrate is very crucial for field electron emitters that are operating under high electric fields. As a supporting precursor of CNT field emitters, we adopted silicon carbide (SiC) nano-particle fillers with Ni particles and then enhanced interfacial reactions onto Kovar-alloy substrates through the optimized wet pulverization process of SiC aggregates for reliable field electron emitters. As-purchased SiC aggregates were efficiently pulverized from 20 to less than 1 micro-meter in a median value (D50). CNT pastes for field emitters were distinctively formulated by a mixing process of the pulverized SiC aggregates and pre-dispersed CNTs. X-ray photoelectron spectroscopy studies showed that the optimally pulverized SiC-CNT paste-emitter had a stronger Si 2p3/2 signal in the Ni2Si phase than the as-purchased one. The Si 2p3/2 signal would represent interfacial reaction of the SiC nano-particle onto Ni from the CNT paste and the Kovar substrate, forming the supporting layer for CNT emitters. The optimal paste-emitter even in a vacuum-sealed tube exhibited a highly reliable field emission current with a high current density of 100 mA cm-2 for over 50 h along with good reproducibility. The enhanced interfacial reaction of SiC filler onto the metal substrates could lead to highly reliable field electron emitters for vacuum electronic devices.
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Affiliation(s)
- Eunsol Go
- ETRI ICT School (Advanced Devices Engineering), University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
- Emerging Devices Research section, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea
| | - Jae-Woo Kim
- Emerging Devices Research section, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea
| | - Jeong-Woong Lee
- ETRI ICT School (Advanced Devices Engineering), University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
- Emerging Devices Research section, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea
| | - Yujung Ahn
- ETRI ICT School (Advanced Devices Engineering), University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
- Emerging Devices Research section, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea
| | - Jin-Woo Jeong
- Emerging Devices Research section, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea
| | - Jun-Tae Kang
- Emerging Devices Research section, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea
| | - Sora Park
- Emerging Devices Research section, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea
| | - Ki Nam Yun
- Emerging Devices Research section, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea
| | - Seong Jun Kim
- Emerging Devices Research section, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea
| | - Sunghee Kim
- Emerging Devices Research section, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea
| | - Ji-Hwan Yeon
- Emerging Devices Research section, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea
| | - Yoon-Ho Song
- ETRI ICT School (Advanced Devices Engineering), University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
- Emerging Devices Research section, Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea
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Laszczyk KU. Field Emission Cathodes to Form an Electron Beam Prepared from Carbon Nanotube Suspensions. MICROMACHINES 2020; 11:mi11030260. [PMID: 32121329 PMCID: PMC7142948 DOI: 10.3390/mi11030260] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 02/20/2020] [Accepted: 02/24/2020] [Indexed: 11/16/2022]
Abstract
In the first decade of our century, carbon nanotubes (CNTs) became a wonderful emitting material for field-emission (FE) of electrons. The carbon nanotube field-emission (CNT-FE) cathodes showed the possibility of low threshold voltage, therefore low power operation, together with a long lifetime, high brightness, and coherent beams of electrons. Thanks to this, CNT-FE cathodes have come ahead of increasing demand for novel self-sustaining and miniaturized devices performing as X-ray tubes, X-ray spectrometers, and electron microscopes, which possess low weight and might work without the need of the specialized equipped room, e.g., in a harsh environment and inaccessible-so-far areas. In this review, the author discusses the current state of CNT-FE cathode research using CNT suspensions. Included in this review are the basics of cathode operation, an evaluation, and fabrication techniques. The cathodes are compared based on performance and correlated issues. The author includes the advancement in field-emission enhancement by postprocess treatments, incorporation of fillers, and the use of film coatings with lower work functions than that of CNTs. Each approach is discussed in the context of the CNT-FE cathode operating factors. Finally, we discuss the issues and perspectives of the CNT-FE cathode research and development.
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Affiliation(s)
- Karolina Urszula Laszczyk
- Wroclaw University of Science and Technology, Faculty of Microelectronic System and Photonics, 50-370 Wroclaw, Poland
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Perales-Martinez IA, Velásquez-García LF. Fully 3D-printed carbon nanotube field emission electron sources with in-plane gate electrode. NANOTECHNOLOGY 2019; 30:495303. [PMID: 31550235 DOI: 10.1088/1361-6528/ab3d17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report the design, fabrication, and experimental characterization of the first fully additively manufactured carbon nanotube (CNT) field emission electron sources. The devices are created via direct ink writing (DIW)-one of the least expensive and most versatile additive manufacturing methods, capable of creating monolithic multi-material objects. The devices are 2.5 cm by 2.5 cm glass substrates coated with two imprints, i.e. a trace made of a CNT ink (the emitting electrode), symmetrically surrounded on both sides by a trace made of Ag microparticle ink (the in-plane extractor gate). The CNT ink is a mixture of (-COOH)-functionalized multiwalled CNTs (MWCNTs), N,N-Dimethylformamide, and ethyl cellulose. Optimization of the formulation of the CNT ink resulted in a MWCNT concentration equal to 0.82 wt% and in imprints with an electrical resistivity equal to 0.78 Ω cm. 3D-printed devices having CNT imprints with active length equal to 25 mm (a single, straight trace with 174.5 μm gap between adjacent Ag microparticle imprints) and 135 mm (a square-loop spiral with 499 μm gap between Ag microparticle adjacent imprints) were characterized in a triode configuration (i.e. using an external anode electrode) at ∼2.5 × 10-7 Torr, yielding emission currents as large as 120 μA (60 μA cm-2), start-up voltages as low as 62 V and gate transmission as high as 99%. The low-cost cold cathode technology is compatible with compact applications such as miniaturized mass spectrometry, handheld x-ray generation, and nanosatellite electric propulsion.
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Affiliation(s)
- Imperio Anel Perales-Martinez
- Escuela de Ingeniería y Ciencias, Tecnológico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N.L., México. Microsystems Technology Laboratories, Massachusetts Institute of Technology, 77 Massachusetts Ave. Cambridge, MA 02139, United States of America
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Kim M, Rho J. Metamaterials and imaging. NANO CONVERGENCE 2015; 2:22. [PMID: 28191408 DOI: 10.1186/s40580-014-0034-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 06/22/2015] [Indexed: 05/23/2023]
Abstract
Resolution of the conventional lens is limited to half the wavelength of the light source by diffraction. In the conventional optical system, evanescent waves, which carry sub-diffraction spatial information, has exponentially decaying amplitude and therefore cannot reach to the image plane. New optical materials called metamaterials have provided new ways to overcome diffraction limit in imaging by controlling the evanescent waves. Such extraordinary electromagnetic properties can be achieved and controlled through arranging nanoscale building blocks appropriately. Here, we review metamaterial-based lenses which offer the new types of imaging components and functions. Perfect lens, superlenses, hyperlenses, metalenses, flat lenses based on metasurfaces, and non-optical lenses including acoustic hyperlens are described. Not all of them offer sub-diffraction imaging, but they provide new imaging mechanisms by controlling and manipulating the path of light. The underlying physics, design principles, recent advances, major limitations and challenges for the practical applications are discussed in this review.
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Affiliation(s)
- Minkyung Kim
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784 Republic of Korea
| | - Junsuk Rho
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784 Republic of Korea ; Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784 Republic of Korea
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