Exploring conductivity in ex-situ doped Si thin films as thickness approaches 5nm

dc.check.date2020-06-14
dc.check.infoAccess to this article is restricted until 12 months after publication by request of the publisher.en
dc.contributor.authorMacHale, John
dc.contributor.authorMeaney, Fintan
dc.contributor.authorKennedy, Fintan
dc.contributor.authorEaton, Luke
dc.contributor.authorMirabelli, Gioele
dc.contributor.authorWhite, Mary
dc.contributor.authorThomas, Kevin
dc.contributor.authorPelucchi, Emanuele
dc.contributor.authorHjorth Petersen, Dirch
dc.contributor.authorLin, Rong
dc.contributor.authorPetkov, Nikolay
dc.contributor.authorConnolly, James
dc.contributor.authorHatem, Chris
dc.contributor.authorGity, Farzan
dc.contributor.authorAnsari, Lida
dc.contributor.authorLong, Brenda
dc.contributor.authorDuffy, Ray
dc.contributor.funderEnterprise Irelanden
dc.contributor.funderHorizon 2020en
dc.contributor.funderEuropean Regional Development Funden
dc.contributor.funderScience Foundation Irelanden
dc.contributor.funderHigher Education Authorityen
dc.date.accessioned2019-08-29T15:24:27Z
dc.date.available2019-08-29T15:24:27Z
dc.date.issued2019-06-14
dc.date.updated2019-08-29T15:16:08Z
dc.description.abstractSilicon (Si) has been scaled below 10 nm in multigate and silicon-on-insulator (SOI) device technologies, but clearly Si thickness cannot be reduced indefinitely, as we will run out of atoms eventually. As thickness approaches 5 nm, surfaces and interfaces will significantly impact the electrical behavior of Si, and surface physics cannot be discounted. Below that, bulk material properties will be altered considerably in the few-monolayer limit. One of the most basic defining properties of a semiconductor is its conductivity. To improve conductivity, while inducing a channel by appropriate biasing, it is necessary to define an accurate impurity doping strategy to reduce parasitic resistance. In this paper, we investigated the changing electrical conductivity of SOI films as a function of the Si thickness, in the range of 3–66 nm. SOI films were ex situ doped using three different approaches: liquid/vapor phase monolayer doping of phosphorus using allyldiphenylphosphine, gas-phase doping of arsenic using arsine (AsH3), and room-temperature beam-line ion implantation of phosphorus. The circular transfer length method and micro-four-point probe measurements were used to determine the resistivity of the Si films, mitigating the contribution from contact resistance. The resistivity of the Si films was observed to increase with decreasing Si film thickness below 20 nm, with a dramatic increase observed for a Si thickness at 4.5 nm. This may drastically impact the number of parallel conduction paths (i.e., nanowires) required in gate-all-around devices. Density functional theory modeling indicates that the surface of the Si film with a thickness of 4.5 nm is energetically more favorable for the dopant atom compared to the core of the film.en
dc.description.sponsorshipEuropean Regional Development Fund ((ERDF) under Ireland’s European Structural and Investment Funds Programmes 2014–2020); Science Foundation Ireland and Science Foundation Ireland (SFI/HEA Irish Centre for High-End Computing (ICHEC));en
dc.description.statusPeer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.articleid225709en
dc.identifier.citationMacHale, J., Meaney, F., Kennedy, N., Eaton, L., Mirabelli, G., White, M., Thomas, K., Pelucchi, E., Petersen, D. H., Lin, R., Petkov, N., Connolly, J., Hatem, C., Gity, F., Ansari, L., Long, B. and Duffy, R. (2019) 'Exploring conductivity in ex-situ doped Si thin films as thickness approaches 5 nm', Journal of Applied Physics, 125(22), 225709 (9 pp).en
dc.identifier.doi10.1063/1.5098307en
dc.identifier.eissn1089-7550
dc.identifier.endpage9en
dc.identifier.issn0021-8979
dc.identifier.journaltitleJournal of Applied Physicsen
dc.identifier.startpage1en
dc.identifier.urihttps://hdl.handle.net/10468/8416
dc.identifier.volume125en
dc.language.isoenen
dc.publisherAIP Publishingen
dc.relation.projectinfo:eu-repo/grantAgreement/EC/H2020::RIA/654384/EU/Access to European Nanoelectronics Network/ASCENTen
dc.relation.urihttps://aip.scitation.org/doi/full/10.1063/1.5098307
dc.rights© 2019 Author(s). Published under license by AIP Publishing.en
dc.subjectSiliconen
dc.subjectPhosphorusen
dc.subjectAL2O3en
dc.subjectModelen
dc.subjectDopingen
dc.subjectSemiconductorsen
dc.subjectDensity functional theoryen
dc.subjectThin filmsen
dc.subjectChemical compounds and componentsen
dc.subjectNanowiresen
dc.subjectGas phaseen
dc.subjectParasitic resistancesen
dc.subjectIon implantationen
dc.titleExploring conductivity in ex-situ doped Si thin films as thickness approaches 5nmen
dc.typeArticle (peer-reviewed)en
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