1
|
Jerng SK, Hong E, Lee G, Lee B, Jeon JH, Kim J, Chun SH. Integration of Vertical Graphene Onto a Tunnelling Cathode for Digital X-Ray Imaging. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2403721. [PMID: 39148365 DOI: 10.1002/advs.202403721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 07/08/2024] [Indexed: 08/17/2024]
Abstract
As an alternative to thermionic X-ray generators, cold-cathode X-ray tubes are being developed for portable and multichannel tomography. Field emission propagating from needle structures such as carbon nanotubes or Si tips currently dominates related research and development, but various obstacles prevent the widespread of this technology. An old but simple electron emission design is the planar tunnelling cathode using a metal-oxide-semiconductor (MOS) structure, which achieves narrow beam dispersion and low supplying voltage. Directly grown vertical graphene (VG) is employed as the gate electrode of MOS and tests its potential as a new emission source. The emission efficiency of the device is initially ≈1% because of unavoidable fabrication damage during the patterning processes; it drastically improves to >40% after ozone treatment. The resulting emission current obeys the Fowler-Nordheim tunnelling model, and the enhanced emission is attributed to the effective gate thickness reduction by ozone treatment. As a proof-of-concept experiment, a clustered array of 2140 cells is integrated into a system that provides mA-class emission current for X-ray generation. With pulsed digital excitations, X-ray imaging of a chest phantom, demonstrating the feasibility of using a VG MOS electron emission source as a new and innovative X-ray generator is realized.
Collapse
Affiliation(s)
| | - Eunju Hong
- Digital X-ray task, Artificial Intelligence Lab, LG Electronics, Seoul, 07796, South Korea
| | - Giwon Lee
- Digital X-ray task, Artificial Intelligence Lab, LG Electronics, Seoul, 07796, South Korea
| | - Byungkee Lee
- Digital X-ray task, Artificial Intelligence Lab, LG Electronics, Seoul, 07796, South Korea
| | - Jae Ho Jeon
- Department of Physics, Sejong University, Seoul, 05006, South Korea
| | - Jinah Kim
- Digital X-ray task, Artificial Intelligence Lab, LG Electronics, Seoul, 07796, South Korea
| | - Seung-Hyun Chun
- Department of Physics, Sejong University, Seoul, 05006, South Korea
| |
Collapse
|
2
|
Guo Y, Li B, Zhang Y, Deng S, Chen J. Characteristics of Carbon Nanotube Cold Cathode Triode Electron Gun Driven by MOSFET Working at Subthreshold Region. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:1260. [PMID: 39120365 PMCID: PMC11314122 DOI: 10.3390/nano14151260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2024] [Revised: 07/24/2024] [Accepted: 07/26/2024] [Indexed: 08/10/2024]
Abstract
The carbon nanotube cold cathode has important applications in the X-ray source, microwave tube, neutralizer, etc. In this study, the characteristics of carbon nanotube (CNT) electron gun in series with metal-oxide-semiconductor field-effect transistor (MOSFET) were studied. CNTs were prepared on a stainless steel substrate by chemical vapor deposition and assembled with a mesh gate to form an electron gun. The anode current of the electron gun can be accurately regulated by precisely controlling the MOSFET gate voltage in the subthreshold region from 1 to 40 µA. The current stability measurements show the cathode current fluctuation was 0.87% under 10 h continuous operation, and the corresponding anode current fluctuation was 2.3%. The result has demonstrated that the MOSFET can be applied for the precise control of the CNT electron gun and greatly improve current stability.
Collapse
Affiliation(s)
| | | | | | | | - Jun Chen
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China; (Y.G.); (B.L.); (Y.Z.); (S.D.)
| |
Collapse
|
3
|
Yao Q, Wu Y, Song G, Xu Z, Ke Y, Zhan R, Chen J, Zhang Y, Deng S. Effect of Crystallinity on the Field Emission Characteristics of Carbon Nanotube Grown on W-Co Bimetallic Catalyst. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:819. [PMID: 38786778 PMCID: PMC11123676 DOI: 10.3390/nano14100819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 04/27/2024] [Accepted: 04/29/2024] [Indexed: 05/25/2024]
Abstract
Carbon nanotube (CNT) is an excellent field emission material. However, uniformity and stability are the key issues hampering its device application. In this work, a bimetallic W-Co alloy was adopted as the catalyst of CNT in chemical vapor deposition process. The high melting point and stable crystal structure of W-Co helps to increase the grown CNT diameter uniformity and homogeneous crystal structure. High-crystallinity CNTs were grown on the W-Co bimetallic catalyst. Its field emission characteristics demonstrated a low turn-on field, high current density, stable current stability, and uniform emission distribution. The Fowler-Nordheim (FN) and Seppen-Katamuki (SK) analyses revealed that the CNT grown on the W-Co catalyst has a relatively low work function and high field enhancement factor. The high crystallinity and homogeneous crystal structure of CNT also reduce the body resistance and increase the emission current stability and maximum current. The result provides a way to synthesis a high-quality CNT field emitter, which will accelerate the development of cold cathode vacuum electronic device application.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Yu Zhang
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-Sen University, Guangzhou 510275, China; (Q.Y.); (Y.W.); (G.S.); (Z.X.); (Y.K.); (R.Z.); (J.C.); (S.D.)
| | | |
Collapse
|
4
|
Xiao D, Du H, Sun L, Suo X, Wang Y, Zhang Y, Zhang S, Kuang S, Hu F, Tu L, Yu D, Song P. Boosting the electron beam transmittance of field emission cathode using a self-charging gate. Nat Commun 2024; 15:764. [PMID: 38278943 PMCID: PMC10817892 DOI: 10.1038/s41467-024-45142-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 01/16/2024] [Indexed: 01/28/2024] Open
Abstract
The gate-type carbon nanotubes cathodes exhibit advantages in long-term stable emission owing to the uniformity of electrical field on the carbon nanotubes, but the gate inevitably reduces the transmittance of electron beam, posing challenges for system stabilities. In this work, we introduce electron beam focusing technique using the self-charging SiNx/Au/Si gate. The potential of SiNx is measured to be approximately -60 V quickly after the cathode turning on, the negative potential can be maintained as the emission goes on. The charged surface generates rebounding electrostatic forces on the following electrons, significantly focusing the electron beam on the center of gate hole and allowing them to pass through gate with minimal interceptions. An average transmittance of 96.17% is observed during 550 hours prototype test, the transmittance above 95% is recorded for the cathode current from 2.14 μA to 3.25 mA with the current density up to 17.54 mA cm-2.
Collapse
Affiliation(s)
- Dongyang Xiao
- School of Optics and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China
| | - Huanhuan Du
- School of Optics and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China
| | - Leimeng Sun
- School of Optics and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China.
| | - Xiaochen Suo
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China
| | - Yurong Wang
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China
| | - Yili Zhang
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China
| | - Shaolin Zhang
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China
| | - Shuangyang Kuang
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, Hubei, China
| | - Fangjing Hu
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China
| | - Liangcheng Tu
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China
- MOE Key Laboratory of TianQin Mission, TianQin Research Center for Gravitational Physics & School of Physics and Astronomy, Frontiers Science Center for TianQin, Gravitational Wave Research Center of CNSA, Sun Yat-sen University (Zhuhai Campus), Zhuhai, 519082, China
| | - Daren Yu
- Lab of Plasma Propulsion, Harbin Institute of Technology (HIT), Harbin, 150001, China
| | - Peiyi Song
- MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China.
| |
Collapse
|
5
|
Insley B, Bartkoski D, Balter P, Prajapati S, Tailor R, Salehpour M, Jaffray D. Proof-of-concept for a thin conical X-ray target optimized for intensity and directionality for use in a carbon nanotube-based compact X-ray tube. Med Phys 2024; 51:447-463. [PMID: 37947472 DOI: 10.1002/mp.16835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 10/20/2023] [Accepted: 10/29/2023] [Indexed: 11/12/2023] Open
Abstract
BACKGROUND Carbon nanotube-based cold cathode technology has revolutionized the miniaturization of X-ray tubes. However, current applications of these devices required optimization for large, uniform fields with low intensity. PURPOSE This work investigated the feasibility and radiological characteristics of a novel conical X-ray target optimized for high intensity and high directionality to be used in a compact X-ray tube. METHODS The proposed device uses an ultrathin, conical tungsten-diamond target that exhibits significant heat loading while maintaining a small focal spot size and promoting forward-directedness of the X-ray field through preferential attenuation of oblique-angled photons. The electrostatic and thermal properties of the theoretical tube were calculated and analyzed using COMSOL Multiphysics software. The production, transport, and calculation of radiological properties associated with the resultant X-ray field were performed using the Geant4 toolkit via its wrapper, TOPAS. RESULTS Heat transfer analysis of this X-ray tube demonstrated the feasibility of a 200-kV electron beam bombarding the proposed target at a maximum current of 100 mA using a 1-ms symmetric duty cycle. The cathode of the X-ray tube was designed to be segmented into nine switchable electrical segments for modulation of the focal spot size from 0.4- to 10.8-mm. After importing the COMSOL-derived electron beam into TOPAS for X-ray production simulations, radiological analysis of the resultant field demonstrated high levels of intrinsic beam collimation while maintaining high intensity. A maximum dose rate of 17,887 cGy/min was calculated for 1-mm depth in water at 7-cm distance. CONCLUSIONS The proposed X-ray tube design can create highly directional X-ray fields with superior fluence compared to that of current commercial X-ray tubes of comparable size.
Collapse
Affiliation(s)
- Ben Insley
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Dirk Bartkoski
- Empyrean Medical Systems, Inc., 950 Peninsula Corp Cir, Boca Raton, USA
| | - Peter Balter
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Surendra Prajapati
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Ramesh Tailor
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Mohammad Salehpour
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - David Jaffray
- Division of Office of the Sr. VP & Chief Technology and Digital Officer, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| |
Collapse
|
6
|
Han SE, Go H, Lee H, Lee CJ. Densification effect on field emission characteristics of CNT film emitters for electron emission devices. NANOTECHNOLOGY 2023; 35:065701. [PMID: 37852212 DOI: 10.1088/1361-6528/ad0482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 10/17/2023] [Indexed: 10/20/2023]
Abstract
Field electron emission characteristics of the carbon nanotube (CNT) film emitters were investigated according to densification conditions such as nitric acid, acetic acid, and salicylic acid. The emission performance of the CNT film emitters was strongly affected by the densification conditions. Salicylic acid exhibits the best field electron emission properties of the CNT film emitters, followed by nitric acid and acetic acid. The efficient densification of the CNT film emitter by salicylic acid is caused by the role of polarity and p orbitals, nitric acid by hydrogen ions, and acetic acid by weak polarity. After the densification with salicylic acid, the turn-on field of the CNT film emitter decreases from 1.94 Vμm-1to 1.86 Vμm-1, the threshold field decreases from 3.41 Vμm-1to 2.95 Vμm-1, the emission current significantly increases from 20.92 mA to 43.98 mA, and the degradation rate from the long-term emission stability decreases from 49.9% to 21%. The improved emission characteristics are attributed to the increased emission sites at the CNT film and the increased electrical conductivity of the CNT film. The densification is a useful way to enhance the field electron emission properties of CNT film emitters.
Collapse
Affiliation(s)
- Si Eun Han
- School of Electrical Engineering, Korea University, Seoul, 02841, Republic of Korea
- LuminaX Co., Ltd, Seoul, 02841, Republic of Korea
| | - Hanbin Go
- School of Electrical Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Hyunjea Lee
- LuminaX Co., Ltd, Seoul, 02841, Republic of Korea
| | - Cheol Jin Lee
- School of Electrical Engineering, Korea University, Seoul, 02841, Republic of Korea
- LuminaX Co., Ltd, Seoul, 02841, Republic of Korea
| |
Collapse
|
7
|
Lu L, Peng S, Zhao L, Zhang M, Xiao J, Wen H, Zhang P, Yakovlev AN, Qiu J, Yu X, Wang T, Xu X. Visualized X-ray Dosimetry for Multienvironment Applications. NANO LETTERS 2023; 23:8753-8760. [PMID: 37712849 DOI: 10.1021/acs.nanolett.3c02826] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/16/2023]
Abstract
X-ray dose detection plays a critical role in various scientific fields, including chemistry, materials, and medicine. However, the current materials used for this purpose face challenges in both immediate and delayed radiation detections. Here, we present a visual X-ray dosimetry method for multienvironment applications, utilizing NaLuF4 nanocrystals (NCs) that undergo a color change from green to red upon X-ray irradiation. By adjustment of the concentrations of Ho3+, the emission color of the NCs can be tuned thanks to the cross-relaxation effects. Furthermore, X-ray irradiation induces generation of trapping centers in NaLuF4:Ho3+ NCs, endowing the generation of mechanoluminescence (ML) behavior upon mechanical stimulation after X-ray irradiation ceases. The ML intensity shows a linear correlation with the X-ray dose, facilitating the detection of delayed radiation. This breakthrough facilitates X-ray dose inspection in flaw detection, nuclear medicine, customs, and civil protection, thereby enhancing opportunities for radiation monitoring and control.
Collapse
Affiliation(s)
- Lan Lu
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, People's Republic of China
| | - Songcheng Peng
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, People's Republic of China
| | - Lei Zhao
- College of Physics and Optoelectronic Technology, Collaborative Innovation Center of Rare-Earth Functional Materials and Devices Development, Baoji University of Arts and Sciences, Baoji 721016, People's Republic of China
| | - Meiguang Zhang
- College of Physics and Optoelectronic Technology, Collaborative Innovation Center of Rare-Earth Functional Materials and Devices Development, Baoji University of Arts and Sciences, Baoji 721016, People's Republic of China
| | - Jianqiang Xiao
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, People's Republic of China
| | - Hongyu Wen
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, People's Republic of China
| | - Peng Zhang
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, People's Republic of China
| | | | - Jianbei Qiu
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, People's Republic of China
| | - Xue Yu
- School of Mechanical Engineering, Institute for Advanced Materials Deformation and Damage from Multi-Scale, Chengdu University, Chengdu 610106, People's Republic of China
| | - Ting Wang
- School of Materials and Chemistry and Chemical Engineering, Chengdu University of Technology, Chengdu 610059, Sichuan, People's Republic of China
| | - Xuhui Xu
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, People's Republic of China
| |
Collapse
|
8
|
Pickhardt PJ. Abdominal Imaging in the Coming Decades: Better, Faster, Safer, and Cheaper? Radiology 2023; 307:e222551. [PMID: 36916892 DOI: 10.1148/radiol.223087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Affiliation(s)
- Perry J Pickhardt
- From the Department of Radiology, University of Wisconsin School of Medicine & Public Health, 600 Highland Ave, E3/311 Clinical Science Center, Madison, WI 53792-3252
| |
Collapse
|