{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,29]],"date-time":"2026-08-29T05:18:44Z","timestamp":1787980724579,"version":"build-2784847793"},"reference-count":30,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T00:00:00Z","timestamp":1787788800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Science and Technology Council","award":["114-2221-E-390-011"],"award-info":[{"award-number":["114-2221-E-390-011"]}]},{"award":["114-2221-E-390-011"],"award-info":[{"award-number":["114-2221-E-390-011"]}],"id":[{"id":"https:\/\/ror.org\/02kv4zf79","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Micromachines"],"abstract":"<jats:p>This study presents a comprehensive experimental and theoretical investigation into dual-gate field-emission devices fabricated using a standard 0.35 \u00b5m CMOS-MEMS process. Two emitter configurations, the concave-tip and triangular-tip, are characterized, and their performance is rigorously analyzed using three-dimensional simulations based on Fowler\u2013Nordheim emission theory. To account for discrepancies between initial designs and fabricated devices, the influence of critical geometric parameters, including tip apex radius, cathode-anode spacing, and tip sharpness, is systematically evaluated regarding emission current and threshold voltage. Compared to the floating-gate baseline (~38 V), dual-gate (DG) operation lowers the threshold voltage by ~70% (~10 V), enhances low-voltage emission over tenfold, and provides a 3.4-fold boost in differential output conductance. Simulation analysis indicates this improvement stems from enhanced electrostatic field distribution governed by the gates. Furthermore, the top gate, due to its proximity to the emitter tip relative to the bottom gate, provides superior control over emission current at lower operating voltages. Three-dimensional simulations corroborate these findings, revealing that minimizing both the tip radius and cathode-anode spacing substantially enhances tunneling electron flow. Additionally, gate voltage sweeps confirm that electron trajectories are effectively directed by electrostatic steering. These findings establish critical design guidelines for integrating field-emission devices into standard CMOS platforms, facilitating the development of on-chip electrostatically controlled electron sources for integrated vacuum microelectronics.<\/jats:p>","DOI":"10.3390\/mi17091014","type":"journal-article","created":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T10:58:21Z","timestamp":1787828301000},"page":"1014","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Design, Simulation, and Experimental Characterization of a Superimposed Top- and Bottom-Gate Field-Emission Triode Fabricated Using a Post-CMOS MEMS Process"],"prefix":"10.3390","volume":"17","author":[{"given":"Yu-Hsien","family":"Wu","sequence":"first","affiliation":[{"name":"Department of Electrical Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"You-Ting","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ting-Wei","family":"Chang","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5056-5275","authenticated-orcid":false,"given":"Wen-Teng","family":"Chang","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"19696","DOI":"10.1021\/acsnano.3c02916","article-title":"Vacuum tunneling transistor with nano vacuum chamber for harsh environments","volume":"17","author":"Heo","year":"2023","journal-title":"ACS Nano"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2410734","DOI":"10.1002\/advs.202410734","article-title":"Circular-gate nanoscale air channel transistors: Achieving ultralow subthreshold swing and working voltage","volume":"12","author":"Zhao","year":"2025","journal-title":"Adv. Sci."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Bhattacharjee, R., Oberbeck, C., West, J., Del Rio, C.W.S., Chern, W., Karaulac, N., Rughoobur, G., Turchetti, M., Yeung, M., and Nardi, A. (2024, January 23\u201325). Field emitter failure mechanisms and harsh environment robustness studies. Proceedings of the Joint International Vacuum Electronics Conference and International Vacuum Electron Sources Conference (IVEC + IVESC), Monterey, CA, USA.","DOI":"10.1109\/IVECIVESC60838.2024.10694979"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"714","DOI":"10.1016\/j.nanoms.2024.01.002","article-title":"Nanoscale air channel devices-inheritance and breakthrough of vacuum tube","volume":"6","author":"Chen","year":"2024","journal-title":"Nano Mater. Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"052801","DOI":"10.1116\/6.0003823","article-title":"Radio frequency side-gate nanoscale vacuum channel triode","volume":"42","author":"Shen","year":"2024","journal-title":"J. Vac. Sci. Technol. B"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"013505","DOI":"10.1063\/5.0150034","article-title":"Lateral nanoscale field emission comb for frequency mixing","volume":"123","author":"Jones","year":"2023","journal-title":"Appl. Phys. Lett."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"135301","DOI":"10.1088\/1361-6463\/ab642f","article-title":"Study on electrical properties and structure optimization of side-gate nanoscale vacuum channel transistor","volume":"53","author":"Xu","year":"2020","journal-title":"J. Phys. D Appl. Phys."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Xu, J., Lin, C., Li, Y., Zhao, X., Shi, Y., and Zhang, X. (2023). Structure optimization of planar nanoscale vacuum channel transistor. Micromachines, 14.","DOI":"10.3390\/mi14020488"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"022805","DOI":"10.1116\/6.0004317","article-title":"Optimal structural design of nanoscale dual-gate air-channel triode via 3D simulation","volume":"43","author":"Shen","year":"2025","journal-title":"J. Vac. Sci. Technol. B"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"105314","DOI":"10.1063\/1.5123280","article-title":"A 3-dimensional calculation of the field emission current and emission angle of a vacuum transistor as a function of gate voltage and radius of curvature of the emitter","volume":"9","author":"Tsagarakis","year":"2019","journal-title":"AIP Adv."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"7082","DOI":"10.1109\/TED.2024.3462678","article-title":"Modulating the cathode by back-gate for planar nanoscale vacuum\/air channel electron tube","volume":"71","author":"Wang","year":"2024","journal-title":"IEEE Trans. Electron Devices"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1924","DOI":"10.1116\/1.588956","article-title":"Modeling and comparisons of field emitter devices with various geometries","volume":"14","author":"Kang","year":"1996","journal-title":"J. Vac. Sci. Technol. B"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"247","DOI":"10.1016\/j.ultramic.2015.10.018","article-title":"Simulation of the enhancement factor from an individual 3D hemisphere-on-post field emitter by using finite elements method","volume":"160","author":"Roveri","year":"2016","journal-title":"Ultramicroscopy"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"022902","DOI":"10.1116\/1.5063733","article-title":"Minimal domain size necessary to simulate the field enhancement factor numerically with specified precision","volume":"37","year":"2019","journal-title":"J. Vac. Sci. Technol. B"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"5583","DOI":"10.1038\/s41467-025-60607-6","article-title":"Uncovering a widely applicable empirical formula for field emission characteristics of metallic nanotips in nanogaps","volume":"16","author":"Li","year":"2025","journal-title":"Nat. Commun."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"4676","DOI":"10.1038\/srep04676","article-title":"Enhanced cold field emission of large-area arrays of vertically aligned ZnO nanotapers via sharpening: Experiment and theory","volume":"4","author":"Zhang","year":"2014","journal-title":"Sci. Rep."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"3004","DOI":"10.1109\/TED.2026.3669154","article-title":"On-chip field emission triode in a 0.35-\u00b5m CMOS-MEMS process","volume":"73","author":"Tsai","year":"2026","journal-title":"IEEE Trans. Electron Devices"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"292","DOI":"10.1109\/LED.2021.3136875","article-title":"Nanoscale vacuum field emission triode with a double gate structure","volume":"43","author":"Wang","year":"2022","journal-title":"IEEE Electron Device Lett."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"3961","DOI":"10.1109\/TED.2019.2928545","article-title":"Field electrons intercepted by coplanar gates in nanoscale air channel","volume":"66","author":"Chang","year":"2019","journal-title":"IEEE Trans. Electron Devices"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"024503","DOI":"10.1063\/5.0237672","article-title":"Coplanar nanoscale vacuum electron field emission triode with controllable gate distance","volume":"137","author":"Fang","year":"2025","journal-title":"J. Appl. Phys."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"466","DOI":"10.1109\/LED.2022.3148397","article-title":"Gated Si-tip with on-tip integrated gate-all-around field effect transistor for actively controlled field electron emission","volume":"43","author":"Zeng","year":"2022","journal-title":"IEEE Electron Device Lett."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"023201","DOI":"10.1116\/6.0003346","article-title":"Investigation of silicon-on-insulator back-gate nano vacuum channel transistor array","volume":"42","author":"Weng","year":"2024","journal-title":"J. Vac. Sci. Technol. B"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1530","DOI":"10.1134\/S1063784219100177","article-title":"Ten approaches to define the field emission area","volume":"64","author":"Popov","year":"2019","journal-title":"Tech. Phys."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Li, X., and Feng, J. (2023). Review of nanoscale vacuum devices. Electronics, 12.","DOI":"10.3390\/electronics12040802"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Xu, J., Lin, C., Shi, Y., Li, Y., Zhao, X., Zhang, X., and Zhang, J. (2022). Optimization of a field emission electron source based on nano-vacuum channel structures. Micromachines, 13.","DOI":"10.3390\/mi13081274"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"20140811","DOI":"10.1098\/rspa.2014.0811","article-title":"Derivation of a generalized Fowler\u2013Nordheim equation for nanoscopic field-emitters","volume":"471","author":"Kyritsakis","year":"2015","journal-title":"Proc. R. Soc. A"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"021801","DOI":"10.1116\/1.5064403","article-title":"Curvature correction to the field emission current","volume":"37","author":"Biswas","year":"2019","journal-title":"J. Vac. Sci. Technol. B"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"094304","DOI":"10.1063\/5.0138100","article-title":"Fast and accurate determination of the curvature-corrected field emission current","volume":"133","author":"Biswas","year":"2023","journal-title":"J. Appl. Phys."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"2907","DOI":"10.1098\/rspa.2007.0030","article-title":"Reformulation of the standard theory of Fowler\u2013Nordheim tunnelling and cold field electron emission","volume":"463","author":"Forbes","year":"2007","journal-title":"Proc. R. Soc. A"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"5696","DOI":"10.1109\/TED.2024.3436032","article-title":"Diode-like field emission devices fabricated by standard 0.35-\u03bcm CMOS MEMS process","volume":"71","author":"Chang","year":"2024","journal-title":"IEEE Trans. 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