Minimizing interface defects and enhancing optical brightness of µLEDs through polymeric encapsulants

Minimizing interface defects and enhancing optical brightness of µLEDs through polymeric encapsulants | 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 Article Minimizing interface defects and enhancing optical brightness of µLEDs through polymeric encapsulants William Wong, Pranav Gavirneni This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7313012/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract The need for high resolution microLED (µLED) arrays, for applications in chip-level optical interconnects and augmented/virtual reality displays, requires the continuing miniaturization of the LED to reduce the pixel size and enable high pixel density. This miniaturisation degrades the µLED optical brightness due to non-radiative recombination from side-wall defects as the surface-to- volume ratio increases with decreasing µLED size. In this investigation, we demonstrated a fabrication approach combining dry and wet etching processes with polymeric passivation layers, to construct InGaN-based µLEDs that showed negligible degradation due to sidewall effects for devices having diameters as small as 6 µm. The µLEDs exhibited extremely low surface-recombination velocities (<10 cm/s) and high wall plug efficiencies, 𝜂 WPE , of 20.3 % at a current density of 2.5 A/cm 2 with an optical power density of 1.4 W/cm 2 . A simple model was developed to explain the dependence of the µLED performance as a function of the µLED geometry. The model identified the minimum µLED size at which surface-driven degradation becomes dominant and informed the development and demonstration of a fabrication method that reduces these scaling effects in high-resolution displays. Physical sciences/Optics and photonics/Lasers, LEDs and light sources/Inorganic LEDs Physical sciences/Engineering/Electrical and electronic engineering Physical sciences/Physics/Electronics, photonics and device physics/Photonic devices Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SupplementalInformation.pdf Supplementary Information Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version 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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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7313012","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":500230944,"identity":"2149134d-ba9a-49a5-862b-92923953d6ad","order_by":0,"name":"William Wong","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA10lEQVRIiWNgGAWjYPACGyhdQLyWNCBmBmID4rUcJkGLwfkzho8Lfp1P3HD8/MHHFQY2cgzshx/g13Ijx9h4Zt/txA1nkpkNzxikGTPwpOG3y+wG7zZp3p7bidsOJLNJNhgcTmyQIOA8s/NnQVrOJW47/5j9J0QL+wf8Wg7kbpPm+XEgcduNZDZGiBYe/LbY38j/bMzbkGy8/8ZjY6DD0ozZeHLwx45k/7HExzx/7GRn9ic+/NhQYSPHz358A14tYMDYhsRhI6weBP4Qp2wUjIJRMApGKAAA88hH+olOhdQAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0001-7543-9761","institution":"University of Waterloo","correspondingAuthor":true,"prefix":"","firstName":"William","middleName":"","lastName":"Wong","suffix":""},{"id":500230945,"identity":"40ba0c2a-4e2a-45c7-8e98-7175e323261e","order_by":1,"name":"Pranav Gavirneni","email":"","orcid":"https://orcid.org/0000-0001-6497-7978","institution":"University of Waterloo","correspondingAuthor":false,"prefix":"","firstName":"Pranav","middleName":"","lastName":"Gavirneni","suffix":""}],"badges":[],"createdAt":"2025-08-06 21:20:18","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7313012/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7313012/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":90377816,"identity":"b48c4bbe-3522-4276-bac8-d5ebab38827b","added_by":"auto","created_at":"2025-09-02 06:16:21","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3216501,"visible":true,"origin":"","legend":"Article File","description":"","filename":"UwaterloouLEDNatCommManuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7313012/v1_covered_bb953d0c-9ef3-4744-83d7-2ce8584f485b.pdf"},{"id":90377013,"identity":"feed76fd-ed44-42ac-936f-4ac72509c466","added_by":"auto","created_at":"2025-09-02 06:08:26","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":152688,"visible":true,"origin":"","legend":"Supplementary Information","description":"","filename":"SupplementalInformation.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7313012/v1/1e1446b3ab108d7e4692cc61.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Minimizing interface defects and enhancing optical brightness of µLEDs through polymeric encapsulants","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7313012/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7313012/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"The need for high resolution microLED (µLED) arrays, for applications in chip-level optical interconnects and augmented/virtual\r\nreality displays, requires the continuing miniaturization of the LED to reduce the pixel size and enable high pixel density. This\r\nminiaturisation degrades the µLED optical brightness due to non-radiative recombination from side-wall defects as the surface-to-\r\nvolume ratio increases with decreasing µLED size. In this investigation, we demonstrated a fabrication approach combining dry\r\nand wet etching processes with polymeric passivation layers, to construct InGaN-based µLEDs that showed negligible degradation\r\ndue to sidewall effects for devices having diameters as small as 6 µm. The µLEDs exhibited extremely low surface-recombination\r\nvelocities (\u003c10 cm/s) and high wall plug efficiencies, 𝜂\u003csub\u003eWPE\u003c/sub\u003e , of 20.3 % at a current density of 2.5 A/cm\u003csup\u003e2\u003c/sup\u003e with an optical power density of 1.4 W/cm\u003csup\u003e2\u003c/sup\u003e . A simple model was developed to explain the dependence of the µLED performance as a function of the µLED geometry. The model identified the minimum µLED size at which surface-driven degradation becomes dominant and informed the development and demonstration of a fabrication method that reduces these scaling effects in high-resolution displays.","manuscriptTitle":"Minimizing interface defects and enhancing optical brightness of µLEDs through polymeric encapsulants","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-02 06:08:12","doi":"10.21203/rs.3.rs-7313012/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"communications-engineering","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"commseng","sideBox":"Learn more about [Communications Engineering](http://link.springer.com/journal/44172)","snPcode":"44172","submissionUrl":"https://mts-commseng.nature.com/cgi-bin/main.plex","title":"Communications Engineering","twitterHandle":"@commseng","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"686de6b2-7326-4688-a695-e575da7aee75","owner":[],"postedDate":"September 2nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":53138769,"name":"Physical sciences/Optics and photonics/Lasers, LEDs and light sources/Inorganic LEDs"},{"id":53138770,"name":"Physical sciences/Engineering/Electrical and electronic engineering"},{"id":53138771,"name":"Physical sciences/Physics/Electronics, photonics and device physics/Photonic devices"}],"tags":[],"updatedAt":"2025-09-02T06:08:12+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-02 06:08:12","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7313012","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7313012","identity":"rs-7313012","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}