Fabrication of vacancy-independent and intrinsically stable ferroelectric HfO2 through valence-complementary codoping

Fabrication of vacancy-independent and intrinsically stable ferroelectric HfO2 through valence-complementary codoping | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Fabrication of vacancy-independent and intrinsically stable ferroelectric HfO2 through valence-complementary codoping Shutaro Asanunma, Hiroyuki Ota, Yukinori Morita, Shogo Hatayama, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7699479/v3 This work is licensed under a CC BY 4.0 License Status: Posted Version 3 posted You are reading this latest preprint version Show more versions Abstract Ferroelectric HfO 2 is a promising material platform for next-generation devices because it retains ferroelectricity at the nanometer scale and remains compatible with semiconductor processing. In most cases, its ferroelectricity is attributed to a metastable orthorhombic Pca 2 1 phase stabilized by oxygen vacancies. However, the high mobility of oxygen vacancies under an electric field destabilizes this phase and causes remanent-polarization instabilities such as wake-up and fatigue, which limits practical application. Here, a valence-complementary codoping strategy is introduced to stabilize ferroelectricity through cation-induced local electric fields rather than oxygen vacancies. Specifically, Hf4+ is replaced by equimolar Y 3+ and Nb 5+ (6% each), preserving the average cation valence while intentionally creating local charge inhomogeneity and lattice strain. The resulting Y 0.06 Nb 0.06 Hf 0.88 O 2 exhibits a noncentrosymmetric tetragonal P 4 mm structure and remains stable even after annealing in air at 600 °C for 100 h. TaN/YNHO/TaN capacitors endure 10 10 polarization-switching cycles at 3.3 MV cm -1 without wake-up or fatigue, and the frequency dependence of remanent polarization confirms the ferroelectric nature of YNHO. These results demonstrate intrinsically stable, vacancy-independent ferroelectricity and establish valence-complementary codoping as an effective route toward reliable ferroelectric HfO 2 devices. Hard Condensed-matter Physics Materials Science Electronic Materials Nanotechnology Condensed Matter Physics Ceramics and Oxide Materials Ferroelectrics Full Text Additional Declarations The authors declare no competing interests. Supplementary Files SuppementaryInformation.pdf Cite Share Download PDF Status: Posted Version 3 posted You are reading this latest preprint version Show more versions Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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In most cases, its ferroelectricity is attributed to a metastable orthorhombic \u003cem\u003ePca\u003c/em\u003e2\u003csub\u003e1\u003c/sub\u003e phase stabilized by oxygen vacancies. However, the high mobility of oxygen vacancies under an electric field destabilizes this phase and causes remanent-polarization instabilities such as wake-up and fatigue, which limits practical application. Here, a valence-complementary codoping strategy is introduced to stabilize ferroelectricity through cation-induced local electric fields rather than oxygen vacancies. Specifically, Hf4+ is replaced by equimolar Y\u003csup\u003e3+\u003c/sup\u003e and Nb\u003csup\u003e5+\u003c/sup\u003e (6% each), preserving the average cation valence while intentionally creating local charge inhomogeneity and lattice strain. The resulting Y\u003csub\u003e0.06\u003c/sub\u003eNb\u003csub\u003e0.06\u003c/sub\u003eHf\u003csub\u003e0.88\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e exhibits a noncentrosymmetric tetragonal \u003cem\u003eP\u003c/em\u003e4\u003cem\u003emm\u003c/em\u003e structure and remains stable even after annealing in air at 600 °C for 100 h. TaN/YNHO/TaN capacitors endure 10\u003csup\u003e10\u003c/sup\u003e polarization-switching cycles at 3.3 MV cm\u003csup\u003e-1\u003c/sup\u003e without wake-up or fatigue, and the frequency dependence of remanent polarization confirms the ferroelectric nature of YNHO. These results demonstrate intrinsically stable, vacancy-independent ferroelectricity and establish valence-complementary codoping as an effective route toward reliable ferroelectric HfO\u003csub\u003e2\u003c/sub\u003e devices.\u003c/p\u003e","manuscriptTitle":"Fabrication of vacancy-independent and intrinsically stable ferroelectric HfO2 through valence-complementary codoping","msid":"","msnumber":"","nonDraftVersions":[{"code":3,"date":"2026-03-25 19:43:39","doi":"10.21203/rs.3.rs-7699479/v3","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}},{"code":2,"date":"2025-10-07 19:30:25","doi":"10.21203/rs.3.rs-7699479/v2","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}},{"code":1,"date":"2025-09-25 05:12:31","doi":"10.21203/rs.3.rs-7699479/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"596252e6-2030-43f4-93f3-bee167c8d510","owner":[],"postedDate":"March 25th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":55923403,"name":"Hard Condensed-matter Physics"}],"tags":[],"updatedAt":"2025-09-25T05:12:31+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-25 19:43:39","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v3","identity":"rs-7699479","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7699479","identity":"rs-7699479","version":["v3"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}