Lattice matched GeSn/InAlAs heterostructure: Role of Sn in energy band alignment, atomic layer diffusion and photoluminescence

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dc.contributor.authorKarthikeyan, Senguntharen
dc.contributor.authorJoshi, Rutwiken
dc.contributor.authorZhao, Jingen
dc.contributor.authorBodnar, Robert J.en
dc.contributor.authorMagill, Brenden A.en
dc.contributor.authorPleimling, Yannicken
dc.contributor.authorKhodaparast, Giti A.en
dc.contributor.authorHudait, Mantu K.en
dc.date.accessioned2025-03-03T14:05:46Zen
dc.date.available2025-03-03T14:05:46Zen
dc.date.issued2023-07-20en
dc.description.abstractGermanium alloyed with α-tin (GeSn) transitions to a direct bandgap semiconductor of significance for optoelectronics. It is essential to localize the carriers within the active region for improving the quantum efficiency in a GeSn based laser. In this work, epitaxial GeSn heterostructure material systems were analyzed to determine the band offsets for carrier confinement: (i) a 0.53% compressively strained Ge0.97Sn0.03/AlAs; (ii) a 0.81% compressively strained Ge0.94Sn0.06/Ge; and (iii) a lattice matched Ge0.94Sn0.06/In0.12Al0.88As. The phonon modes in GeSn alloys were studied using Raman spectroscopy as a function of Sn composition, that showed Sn induced red shifts in wavenumbers of the Ge-Ge longitudinal optical phonon mode peaks. The material parameter b representing strain contribution to Raman shifts of a Ge0.94Sn0.06 alloy was determined as b = 314.81 ± 14 cm−1. Low temperature photoluminescence measurements were performed at 79 K to determine direct and indirect energy bandgaps of Eg,Γ = 0.72 eV and Eg,L = 0.66 eV for 0.81% compressively strained Ge0.94Sn0.06, and Eg,Γ = 0.73 eV and Eg,L = 0.68 eV for lattice matched Ge0.94Sn0.06 epilayers. Chemical effects of Sn atomic species were analyzed using X-ray photoelectron spectroscopy (XPS), revealing a shift in Ge 3d core level (CL) spectra towards the lower binding energy affecting the bonding environment. Large valence band offset of ΔEV = 0.91 ± 0.1 eV and conduction band offset of ΔEC,Γ-X = 0.64 ± 0.1 eV were determined from the Ge0.94Sn0.06/In0.12Al0.88As heterostructure using CL spectra by XPS measurements. The evaluated band offset was found to be of type-I configuration, needed for carrier confinement in a laser. In addition, these band offset values were compared with the first-principles-based calculated Ge/InAlAs band alignment, and it was found to have arsenic up-diffusion limited to 1 monolayer of epitaxial GeSn overlayer, ruling out the possibility of defects induced modification of band alignment. Furthermore, this lattice matched GeSn/InAlAs heterostructure band offset values were significantly higher than GeSn grown on group IV buffer/substrates. Therefore, a lattice matched GeSn/InAlAs material system has large band offsets offering superior carrier confinement to realize a highly efficient GeSn based photonic device.en
dc.description.versionAccepted versionen
dc.format.extentPages 9472-9485en
dc.format.extent14 page(s)en
dc.identifier.doihttps://doi.org/10.1039/d3tc01018jen
dc.identifier.eissn2050-7534en
dc.identifier.issn2050-7526en
dc.identifier.issue28en
dc.identifier.orcidHudait, Mantu [0000-0002-9789-3081]en
dc.identifier.orcidKhodaparast, Giti [0000-0002-1597-6538]en
dc.identifier.orcidMagill, Brenden [0000-0001-7378-4713]en
dc.identifier.orcidBodnar, Robert [0000-0002-3549-2071]en
dc.identifier.urihttps://hdl.handle.net/10919/124760en
dc.identifier.volume11en
dc.language.isoenen
dc.publisherRoyal Society Chemistryen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.titleLattice matched GeSn/InAlAs heterostructure: Role of Sn in energy band alignment, atomic layer diffusion and photoluminescenceen
dc.title.serialJournal of Materials Chemistry Cen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten
dc.type.otherArticleen
dc.type.otherJournalen
pubs.organisational-groupVirginia Techen
pubs.organisational-groupVirginia Tech/Scienceen
pubs.organisational-groupVirginia Tech/Science/Geosciencesen
pubs.organisational-groupVirginia Tech/Science/Physicsen
pubs.organisational-groupVirginia Tech/Engineeringen
pubs.organisational-groupVirginia Tech/Engineering/Electrical and Computer Engineeringen
pubs.organisational-groupVirginia Tech/University Distinguished Professorsen
pubs.organisational-groupVirginia Tech/All T&R Facultyen
pubs.organisational-groupVirginia Tech/Engineering/COE T&R Facultyen
pubs.organisational-groupVirginia Tech/Science/COS T&R Facultyen

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