Atomic Layer Deposited Tantalum Silicate on Crystallographically-Oriented Epitaxial Germanium: Interface Chemistry and Band Alignment

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dc.contributor.authorClavel, Michael B.en
dc.contributor.authorBhattacharya, Shuvodipen
dc.contributor.authorHudait, Mantu K.en
dc.date.accessioned2023-02-21T17:51:03Zen
dc.date.available2023-02-21T17:51:03Zen
dc.date.issued2022-05-13en
dc.date.updated2023-02-17T19:51:45Zen
dc.description.abstractThe interface chemistry and energy band alignment properties of atomic layer deposited (ALD) tantalum silicate (TaSiOx) dielectrics on crystallographically-oriented, epitaxial (001)Ge, (110)Ge, and (111)Ge thin-films, grown on GaAs substrates by molecular beam epitaxy, were investigated. The ALD process, consisting of a 6 : 1 Ta : Si precursor super-cycle, was analyzed via sputter depth-dependent elemental analysis utilizing X-ray photoelectron spectroscopy (XPS). The XPS investigations revealed uniform Si incorporation throughout the TaSiOx dielectric, and a measurable amount of cross-diffusion between Ge and Ta atomic species in the vicinity of the oxide/semiconductor heterointerface. The formation of a thin SiO2 interfacial oxide, through the intentional pre-pulsing of the Si precursor prior to the Si : Ta super-cycle process, was observed via cross-sectional transmission electron microscopy analysis. Moreover, the bandgap of Ta-rich Ta0.8Si0.2Ox dielectrics, analyzed using the photoelectron energy loss technique centered on the O 1s binding energy spectra, was determined to be in the range of 4.62 eV-4.66 eV (±0.06 eV). Similarly, the XPS-derived valence band and conduction band offsets (ΔEV and ΔEC, respectively) were found to be ΔEV > 3.0 ± 0.1 eV and ΔEC > 0.6 ± 0.1 eV for the (001)Ge, (110)Ge, and (111)Ge orientations, promoting the increased carrier confinement necessary for reducing operational and off-state leakage current in metal-oxide-semiconductor devices. Thus, the empirical TaSiOx/Ge interfacial energy band offsets, coupled with the uniform dielectric deposition observed herein, provides key guidance for the integration of TaSiOx dielectrics with Ge-based field-effect transistors targeting ultra-low power logic applications.en
dc.description.versionSubmitted versionen
dc.format.extentPages 5001-5011en
dc.format.mimetypeapplication/pdfen
dc.identifier.doihttps://doi.org/10.1039/d2ma00208fen
dc.identifier.eissn2633-5409en
dc.identifier.issn2633-5409en
dc.identifier.issue12en
dc.identifier.orcidHudait, Mantu [0000-0002-9789-3081]en
dc.identifier.urihttp://hdl.handle.net/10919/113890en
dc.identifier.volume3en
dc.language.isoenen
dc.publisherRoyal Society of Chemistryen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.titleAtomic Layer Deposited Tantalum Silicate on Crystallographically-Oriented Epitaxial Germanium: Interface Chemistry and Band Alignmenten
dc.title.serialRSC Materials Advancesen
dc.typeArticleen
dc.type.dcmitypeTexten
dc.type.otherArticleen
pubs.organisational-group/Virginia Techen
pubs.organisational-group/Virginia Tech/Engineeringen
pubs.organisational-group/Virginia Tech/Engineering/Electrical and Computer Engineeringen
pubs.organisational-group/Virginia Tech/All T&R Facultyen
pubs.organisational-group/Virginia Tech/Engineering/COE T&R Facultyen

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