{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T09:13:24Z","timestamp":1788254004095,"version":"build-2803163510"},"reference-count":26,"publisher":"American Chemical Society (ACS)","issue":"33","license":[{"start":{"date-parts":[[2026,8,11]],"date-time":"2026-08-11T00:00:00Z","timestamp":1786406400000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-029"},{"start":{"date-parts":[[2026,8,11]],"date-time":"2026-08-11T00:00:00Z","timestamp":1786406400000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-037"},{"start":{"date-parts":[[2026,8,11]],"date-time":"2026-08-11T00:00:00Z","timestamp":1786406400000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-045"}],"funder":[{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["RS-2026-25487626"],"award-info":[{"award-number":["RS-2026-25487626"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/na","name":"Samsung Electronics","doi-asserted-by":"publisher","award":["NA"],"award-info":[{"award-number":["NA"]}],"id":[{"id":"10.13039\/na","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,8,26]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Direct three-dimensional visualization of conductive filaments (CFs) in valence change memory is essential for resolving whether their spatial evolution is governed by stochastic defect generation or by electrode geometry. Here, we apply conductive atomic force microscopy tomography to a TiO2 (10 nm)\/Pt structure, extending this technique to TiO2-based CFs previously inaccessible to tomographic characterization. The tomogram reveals a reverse-cone morphology whose terminus preferentially connects to a Pt bottom electrode (BE) protrusion, evidencing dual field enhancement at both interfaces. Current gradient analysis reveals a nonmonotonic conductivity profile, with values of 0.1355, 0.0682, and 0.1035 nA\/nm at the top, middle, and bottom, consistent with lateral electrostatic confinement by the BE protrusion. Competing exponential field dependence of vacancy generation and linear field dependence of drift accounts for the near-tip constriction. These results establish the BE morphology as an active confinement mechanism and identify nanoscale BE roughness as a key parameter influencing switching variability in resistive random access memory.<\/jats:p>","DOI":"10.1021\/acs.nanolett.6c02423","type":"journal-article","created":{"date-parts":[[2026,8,11]],"date-time":"2026-08-11T11:02:23Z","timestamp":1786446143000},"page":"11060-11066","source":"Crossref","is-referenced-by-count":0,"title":["Three-Dimensional\nVisualization of Conductive Filaments\nin TiO2 via Conductive Atomic Force Microscopy Tomography"],"prefix":"10.1021","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0009-0007-2698-4078","authenticated-orcid":true,"given":"Kunwoo","family":"Park","sequence":"first","affiliation":[{"name":"Korea Advanced Institute of Science and Technology (KAIST) , , ,","place":["Daejeon, Republic of Korea, 34141"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chaewon","family":"Gong","sequence":"additional","affiliation":[{"name":"Korea Advanced Institute of Science and Technology (KAIST) , , ,","place":["Daejeon, Republic of Korea, 34141"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-5361-6684","authenticated-orcid":true,"given":"Sunghwan","family":"Park","sequence":"additional","affiliation":[{"name":"Korea Advanced Institute of Science and Technology (KAIST) , , ,","place":["Daejeon, Republic of Korea, 34141"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7165-8211","authenticated-orcid":true,"given":"Sang-Hee Ko","family":"Park","sequence":"additional","affiliation":[{"name":"Korea Advanced Institute of Science and Technology (KAIST) , , ,","place":["Daejeon, Republic of Korea, 34141"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2667-1983","authenticated-orcid":true,"given":"Seungbum","family":"Hong","sequence":"additional","affiliation":[{"name":"Korea Advanced Institute of Science and Technology (KAIST) , , ,","place":["Daejeon, Republic of Korea, 34141"]},{"name":"Korea Advanced Institute of Science and Technology (KAIST) , , ,","place":["Daejeon, Republic of Korea, 34141"]},{"name":"Korea Advanced Institute of Science and Technology (KAIST) , , ,","place":["Daejeon, Republic of Korea, 34141"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,8,11]]},"reference":[{"issue":"7191","key":"2026090104154930900_cit1","doi-asserted-by":"publisher","first-page":"80","DOI":"10.1038\/nature06932","article-title":"The missing memristor\nfound","volume":"453","author":"Strukov","year":"2008","journal-title":"Nature"},{"issue":"7","key":"2026090104154930900_cit2","doi-asserted-by":"publisher","first-page":"076502","DOI":"10.1088\/0034-4885\/75\/7\/076502","article-title":"Emerging\nmemories: resistive switching\nmechanisms and current status","volume":"75","author":"Jeong","year":"2012","journal-title":"Rep. Prog. Phys."},{"issue":"1","key":"2026090104154930900_cit3","doi-asserted-by":"publisher","first-page":"13","DOI":"10.1038\/nnano.2012.240","article-title":"Memristive\ndevices for computing","volume":"8","author":"Yang","year":"2013","journal-title":"Nature Nanotechnol."},{"issue":"11","key":"2026090104154930900_cit4","doi-asserted-by":"publisher","first-page":"833","DOI":"10.1038\/nmat2023","article-title":"Nanoionics-based resistive switching memories","volume":"6","author":"Waser","year":"2007","journal-title":"Nat. Mater."},{"issue":"2","key":"2026090104154930900_cit5","doi-asserted-by":"publisher","first-page":"148","DOI":"10.1038\/nnano.2009.456","article-title":"Atomic structure of conducting nanofilaments\nin TiO2 resistive switching memory","volume":"5","author":"Kwon","year":"2010","journal-title":"Nat. Nanotechnol."},{"issue":"1","key":"2026090104154930900_cit6","doi-asserted-by":"publisher","first-page":"1800143","DOI":"10.1002\/aelm.201800143","article-title":"Recommended Methods to Study Resistive Switching Devices","volume":"5","author":"Lanza","year":"2019","journal-title":"Advanced Electronic Materials"},{"key":"2026090104154930900_cit7","doi-asserted-by":"publisher","first-page":"171","DOI":"10.1016\/j.mee.2015.04.025","article-title":"Causes and\nconsequences of the stochastic aspect of filamentary RRAM","volume":"147","author":"Degraeve","year":"2015","journal-title":"Microelectron. Eng."},{"key":"2026090104154930900_cit8","doi-asserted-by":"publisher","first-page":"67","DOI":"10.1016\/j.mee.2013.06.001","article-title":"Scanning probe microscopy as a scalpel\nto probe filament formation in conductive bridging memory devices","volume":"120","author":"Celano","year":"2014","journal-title":"Microelectron. Eng."},{"issue":"5","key":"2026090104154930900_cit9","doi-asserted-by":"publisher","first-page":"2401","DOI":"10.1021\/nl500049g","article-title":"Three-Dimensional\nObservation of the Conductive Filament\nin Nanoscaled Resistive Memory Devices","volume":"14","author":"Celano","year":"2014","journal-title":"Nano\nLett."},{"issue":"7","key":"2026090104154930900_cit10","doi-asserted-by":"publisher","first-page":"075706","DOI":"10.1088\/1361-6528\/ab53a9","article-title":"Conductive\nfilament shape in HfO2 electrochemical metallization cells under a\nrange of forming voltages","volume":"31","author":"Clarke","year":"2020","journal-title":"Nanotechnology"},{"issue":"10","key":"2026090104154930900_cit11","doi-asserted-by":"publisher","first-page":"2209925","DOI":"10.1002\/adma.202209925","article-title":"Three-Dimensional Reconstruction\nof Conductive Filaments in HfOx-Based Memristor","volume":"35","author":"Wei","year":"2023","journal-title":"Adv. Mater."},{"key":"2026090104154930900_cit12","doi-asserted-by":"crossref","unstructured":"Zhang, W.; Tang, J.; Gao, B.; Sun, W.; Liu, W.; Wang, K.; Wu, W.; Qian, H.; Wu, H.\n          Impact of Bottom Electrode\nRoughness on the Analog Switching Characteristics in Nanoscale RRAM\nArray.  2021 Device Research Conference (DRC), June 20\u201323, 2021; DRC, 2021; pp 1 and 2. 10.1109\/DRC52342.2021.9467220.","DOI":"10.1109\/DRC52342.2021.9467220"},{"key":"2026090104154930900_cit13","doi-asserted-by":"publisher","first-page":"111194","DOI":"10.1016\/j.mee.2019.111194","article-title":"Impact of roughness of TiN bottom electrode\non the forming voltage of HfO2 based resistive memories","volume":"221","author":"Charpin-Nicolle","year":"2020","journal-title":"Microelectron. 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Lett."},{"issue":"1","key":"2026090104154930900_cit17","doi-asserted-by":"publisher","first-page":"7844","DOI":"10.1038\/srep07844","article-title":"Dual Conical Conducting Filament\nModel in Resistance Switching TiO2 Thin Films","volume":"5","author":"Kim","year":"2015","journal-title":"Sci. Rep."},{"issue":"2","key":"2026090104154930900_cit18","doi-asserted-by":"publisher","first-page":"155","DOI":"10.1080\/00018732.2022.2084006","article-title":"Nanoionic\nmemristive phenomena in\nmetal oxides: the valence change mechanism","volume":"70","author":"Dittmann","year":"2021","journal-title":"Adv. Phys."},{"issue":"7","key":"2026090104154930900_cit19","doi-asserted-by":"publisher","first-page":"429","DOI":"10.1038\/nnano.2008.160","article-title":"Memristive switching mechanism for\nmetal\/oxide\/metal\nnanodevices","volume":"3","author":"Yang","year":"2008","journal-title":"Nat. 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