Interfacial band alignment and structural properties of nanoscale TiO2 thin films for integration with epitaxial crystallographic oriented germanium

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dc.contributorVirginia Tech. Bradley Department of Electrical and Computer Engineering. Advanced Devices & Sustainable Energy Laboratory (ADSEL)en
dc.contributorVirginia Tech. Center for Energy Harvesting Materials and Systems (CEHMS)en
dc.contributor.authorJain, Nikhilen
dc.contributor.authorZhu, Yizhengen
dc.contributor.authorMaurya, Deepamen
dc.contributor.authorVarghese, Ronnieen
dc.contributor.authorPriya, Shashanken
dc.contributor.authorHudait, Mantu K.en
dc.contributor.departmentElectrical and Computer Engineeringen
dc.date.accessed2015-04-24en
dc.date.accessioned2015-05-04T16:58:30Zen
dc.date.available2015-05-04T16:58:30Zen
dc.date.issued2014-01-14en
dc.description.abstractWe have investigated the structural and band alignment properties of nanoscale titanium dioxide (TiO2) thin films deposited on epitaxial crystallographic oriented Ge layers grown on (100), (110), and (111) A GaAs substrates by molecular beam epitaxy. The TiO2 thin films deposited at low temperature by physical vapor deposition were found to be amorphous in nature, and high-resolution transmission electron microscopy confirmed a sharp heterointerface between the TiO2 thin film and the epitaxially grown Ge with no traceable interfacial layer. A comprehensive assessment on the effect of substrate orientation on the band alignment at the TiO2/Ge heterointerface is presented by utilizing x-ray photoelectron spectroscopy and spectroscopic ellipsometry. A band-gap of 3.33 +/- 0.02 eV was determined for the amorphous TiO2 thin film from the Tauc plot. Irrespective of the crystallographic orientation of the epitaxial Ge layer, a sufficient valence band-offset of greater than 2 eV was obtained at the TiO2/Ge heterointerface while the corresponding conduction band-offsets for the aforementioned TiO2/Ge system were found to be smaller than 1 eV. A comparative assessment on the effect of Ge substrate orientation revealed a valence band-offset relation of Delta E-V(100)> Delta E-V(111)> Delta E-V(110) and a conduction band-offset relation of Delta E-C(110) > Delta E-C(111)> Delta E-C(100). These band-offset parameters are of critical importance and will provide key insight for the design and performance analysis of TiO2 for potential high-k dielectric integration and for future metal-insulator-semiconductor contact applications with next generation of Ge based metal-oxide field-effect transistors. (C) 2014 AIP Publishing LLC.en
dc.description.sponsorshipNational Science Foundation - Grant No. ECCS-1348653en
dc.description.sponsorshipIntel Corporationen
dc.description.sponsorshipU.S. Department of Energy. Office of Basic Energy Science - Grant No. DE-FG02-06ER46290en
dc.format.extent9 pagesen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationJain, N., Zhu, Y., Maurya, D., Varghese, R., Priya, S., Hudait, M. K. (2014). Interfacial band alignment and structural properties of nanoscale TiO2 thin films for integration with epitaxial crystallographic oriented germanium. Journal of Applied Physics, 115(2). doi: 10.1063/1.4861137en
dc.identifier.doihttps://doi.org/10.1063/1.4861137en
dc.identifier.issn0021-8979en
dc.identifier.urihttp://hdl.handle.net/10919/51972en
dc.identifier.urlhttp://scitation.aip.org/content/aip/journal/jap/115/2/10.1063/1.4861137en
dc.language.isoenen
dc.publisherAmerican Institute of Physicsen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectGermaniumen
dc.subjectElemental semiconductorsen
dc.subjectEpitaxyen
dc.subjectThin film depositionen
dc.subjectX-ray photoelectron spectroscopyen
dc.titleInterfacial band alignment and structural properties of nanoscale TiO2 thin films for integration with epitaxial crystallographic oriented germaniumen
dc.title.serialJournal of Applied Physicsen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten

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