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Roy A, Ta BQ, Azadmehr M, Aasmundtveit KE. Post-CMOS processing challenges and design developments of CMOS-MEMS microheaters for local CNT synthesis. MICROSYSTEMS & NANOENGINEERING 2023; 9:136. [PMID: 37937184 PMCID: PMC10625928 DOI: 10.1038/s41378-023-00598-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 07/31/2023] [Accepted: 08/16/2023] [Indexed: 11/09/2023]
Abstract
Carbon nanotubes (CNTs) can be locally grown on custom-designed CMOS microheaters by a thermal chemical vapour deposition (CVD) process to utilize the sensing capabilities of CNTs in emerging micro- and nanotechnology applications. For such a direct CMOS-CNT integration, a key requirement is the development of necessary post-processing steps on CMOS chips for fabricating CMOS-MEMS polysilicon heaters that can locally generate the required CNT synthesis temperatures (~650-900 °C). In our post-CMOS processing, a subtractive fabrication technique is used for micromachining the polysilicon heaters, where the passivation layers in CMOS are used as masks to protect the electronics. For dielectric etching, it is necessary to achieve high selectivity, uniform etching and a good etch rate to fully expose the polysilicon layers without causing damage. We achieved successful post-CMOS processing by developing two-step reactive ion etching (RIE) of the SiO2 dielectric layer and making design improvements to a second-generation CMOS chip. After the dry etching process, CMOS-MEMS microheaters are partially suspended by SiO2 wet etching with minimum damage to the exposed aluminium layers, to obtain high thermal isolation. The fabricated microheaters are then successfully utilized for synthesizing CNTs by a local thermal CVD process. The CMOS post-processing challenges and design aspects to fabricate CMOS-MEMS polysilicon microheaters for such high-temperature applications are detailed in this article. Our developed process for heterogeneous monolithic integration of CMOS-CNT shows promise for wafer-level manufacturing of CNT-based sensors by incorporating additional steps in an already existing foundry CMOS process.
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Affiliation(s)
- Avisek Roy
- Department of Microsystems, University of South-Eastern Norway, 3184 Horten, Norway
| | - Bao Q. Ta
- Department of Microsystems, University of South-Eastern Norway, 3184 Horten, Norway
| | - Mehdi Azadmehr
- Department of Microsystems, University of South-Eastern Norway, 3184 Horten, Norway
| | - Knut E. Aasmundtveit
- Department of Microsystems, University of South-Eastern Norway, 3184 Horten, Norway
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Liu Z, Li B, Li Z, Zhang H. Pillar[n]arene-Mimicking/Assisted/Participated Carbon Nanotube Materials. MATERIALS (BASEL, SWITZERLAND) 2022; 15:6119. [PMID: 36079500 PMCID: PMC9458132 DOI: 10.3390/ma15176119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 06/15/2023]
Abstract
The recent progress in pillar[n]arene-assisted/participated carbon nanotube hybrid materials were initially summarized and discussed. The molecular structure of pillar[n]arene could serve different roles in the fabrication of attractive carbon nanotube-based materials. Firstly, pillar[n]arene has the ability to provide the structural basis for enlarging the cylindrical pillar-like architecture by forming one-dimensional, rigid, tubular, oligomeric/polymeric structures with aromatic moieties as the linker, or forming spatially "closed", channel-like, flexible structures by perfunctionalizing with peptides and with intramolecular hydrogen bonding. Interestingly, such pillar[n]arene-based carbon nanotube-resembling structures were used as porous materials for the adsorption and separation of gas and toxic pollutants, as well as for artificial water channels and membranes. In addition to the art of organic synthesis, self-assembly based on pillar[n]arene, such as self-assembled amphiphilic molecules, is also used to promote and control the dispersion behavior of carbon nanotubes in solution. Furthermore, functionalized pillar[n]arene derivatives integrated carbon nanotubes to prepare advanced hybrid materials through supramolecular interactions, which could also incorporate various compositions such as Ag and Au nanoparticles for catalysis and sensing.
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Affiliation(s)
- Zhaona Liu
- Medical School, Xi’an Peihua University, Xi’an 710125, China
| | - Bing Li
- School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an 710049, China
| | - Zhizheng Li
- School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an 710049, China
| | - Huacheng Zhang
- School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an 710049, China
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Tabata H, Matsuyama H, Goto T, Kubo O, Katayama M. Visible-Light-Activated Response Originating from Carrier-Mobility Modulation of NO 2 Gas Sensors Based on MoS 2 Monolayers. ACS NANO 2021; 15:2542-2553. [PMID: 33528994 DOI: 10.1021/acsnano.0c06996] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Some gas sensors exhibit significant increases in their sensitivity and response/recovery rates under light illumination. This photoactivation of the gas response is considered a promising alternative to conventional thermal activation, which requires high power consumption. Thin layers of molybdenum disulfide (MoS2) are known to exhibit an effective photoactivated gas response under visible light. However, the mechanism of the photoactivated response has not yet been studied in detail. In this study, we fabricated field-effect-transistor (FET) gas sensors based on MoS2 monolayers and investigated their photoactivated gas responses to NO2 gas under illumination at various irradiances of visible light. A photocurrent was generated mainly due to the photovoltaic effect, which decreased upon exposure to NO2. The conductance-based sensor response showed a dependence on NO2 concentration according to the Langmuir adsorption isotherm, thereby suggesting that the response is proportional to the surface coverage of NO2 molecules on the MoS2 layer. The response and recovery rates showed a linear increase with increasing irradiance. Analysis based on the Langmuir adsorption model revealed that both photostimulated adsorption and desorption are involved in the photoactivated response. In contrast, despite the strong dependence of the photocurrent on the irradiance, the magnitude of the sensor response was independent of the irradiance. Based on this result and the change in transfer characteristics of the FET during NO2 exposure, we concluded that the fast response/recovery of the photoactivated response is due to the carrier mobility modulation of MoS2, which is caused by the dipole scattering of adsorbed NO2 molecules.
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Affiliation(s)
- Hiroshi Tabata
- Division of Electrical, Electronic and Infocommunications Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hiroaki Matsuyama
- Division of Electrical, Electronic and Infocommunications Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Taishi Goto
- Division of Electrical, Electronic and Infocommunications Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Osamu Kubo
- Division of Electrical, Electronic and Infocommunications Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Mitsuhiro Katayama
- Division of Electrical, Electronic and Infocommunications Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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Li J, Xu J, Xie Z, Gao X, Zhou J, Xiong Y, Chen C, Zhang J, Liu Z. Diatomite-Templated Synthesis of Freestanding 3D Graphdiyne for Energy Storage and Catalysis Application. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1800548. [PMID: 29603430 DOI: 10.1002/adma.201800548] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 02/13/2018] [Indexed: 06/08/2023]
Abstract
Graphdiyne (GDY), a new kind of two-dimensional (2D) carbon allotropes, has extraordinary electrical, mechanical, and optical properties, leading to advanced applications in the fields of energy storage, photocatalysis, electrochemical catalysis, and sensors. However, almost all reported methods require metallic copper as a substrate, which severely limits their large-scale application because of the high cost and low specific surface area (SSA) of copper substrate. Here, freestanding three-dimensional GDY (3DGDY) is successfully prepared using naturally abundant and inexpensive diatomite as template. In addition to the intrinsic properties of GDY, the fabricated 3DGDY exhibits a porous structure and high SSA that enable it to be directly used as a lithium-ion battery anode material and a 3D scaffold to create Rh@3DGDY composites, which would hold great potential applications in energy storage and catalysts, respectively.
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Affiliation(s)
- Jiaqiang Li
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
- College of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 401331, P. R. China
| | - Jing Xu
- College of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 401331, P. R. China
| | - Ziqian Xie
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
| | - Xin Gao
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
| | - Jingyuan Zhou
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
| | - Yan Xiong
- College of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 401331, P. R. China
| | - Changguo Chen
- College of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 401331, P. R. China
| | - Jin Zhang
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
| | - Zhongfan Liu
- Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
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