Electronic and optical properties of SixGe1-x-ySny alloys lattice-matched to Ge

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dc.contributor.authorPearce, Phoebe M.
dc.contributor.authorBroderick, Christopher A.
dc.contributor.authorNielsen, Michael P.
dc.contributor.authorJohnson, Andrew D.
dc.contributor.authorEkins-Daukes, Nicholas J.
dc.contributor.funderEngineering and Physical Sciences Research Councilen
dc.contributor.funderNational University of Irelanden
dc.contributor.funderScience Foundation Irelanden
dc.contributor.funderRoyal Societyen
dc.contributor.funderRoyal Irish Academyen
dc.date.accessioned2022-04-13T14:23:21Z
dc.date.available2022-04-13T14:23:21Z
dc.date.issued2022-01-18
dc.date.updated2022-04-13T13:58:39Z
dc.description.abstractWe present a combined experimental and theoretical analysis of the evolution of the near-band-gap electronic and optical properties of SixGe1-x-ySny alloys lattice-matched to Ge and GaAs substrates. We perform photoreflectance (PR) and photoluminescence (PL) measurements on SixGe1-x-ySny epitaxial layers grown via chemical vapor deposition for Si (Sn) compositions up to x=9.6% (y=2.5%). Our measurements indicate the presence of an indirect fundamental band gap, with PL observed Ë 200-250 meV lower in energy than the direct E0 transition identified by PR measurements. The measured PL is Ge-like, suggesting that the alloy conduction band (CB) edge is primarily derived from the Ge L-point CB minimum. Interpretation of the PR and PL measurements is supported by atomistic electronic structure calculations. Effective alloy band structures calculated via density functional theory confirm the presence of an indirect fundamental band gap, and reveal the origin of the observed inhomogeneous broadening of the measured optical spectra as being alloy-induced band hybridization occurring close in energy to the CB edge. To analyze the evolution of the band gap, semiempirical tight-binding (TB) calculations are employed to enable calculations for large supercell sizes. TB calculations reveal that the alloy CB edge is hybridized in nature, consisting at low Si and Sn compositions of an admixture of Ge L-, G-, and X-point CB edge states, and confirm that the alloy CB edge retains primarily Ge L-point CB edge character. Our experimental measurements and theoretical calculations confirm a direct transition energy close to 1 eV in magnitude for Si and Sn compositions x=6.8%-9.6% and y=1.6%-2.2%.en
dc.description.sponsorshipEngineering and Physical Sciences Research Council (CASE Studentship); National University of Ireland (Post-Doctoral Fellowship in the Sciences); Royal Society (Industry Fellowship); Royal Irish Academy (Charlemont Grant)en
dc.description.statusPeer revieweden
dc.description.versionPublished Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.articleid015402en
dc.identifier.citationPearce, P. M., Broderick, C. A., Nielsen, M. P., Johnson, A. D. and Ekins-Daukes, N. J. (2022) 'Electronic and optical properties of SixGe1-x-ySny alloys lattice-matched to Ge', Physical Review Materials, 6(1), 015402 (15pp). doi: 10.1103/PhysRevMaterials.6.015402en
dc.identifier.doi10.1103/PhysRevMaterials.6.015402en
dc.identifier.eissn2475-9953
dc.identifier.endpage15en
dc.identifier.issued1en
dc.identifier.journaltitlePhysical Review Materialsen
dc.identifier.startpage1en
dc.identifier.urihttps://hdl.handle.net/10468/13084
dc.identifier.volume6en
dc.language.isoenen
dc.publisherAmerican Physical Societyen
dc.relation.projectinfo:eu-repo/grantAgreement/SFI/SFI Investigator Programme/15/IA/3082/IE/Multiscale Simulation and Analysis of emerging Group IV and III-V Semiconductor Materials and Devices/en
dc.rights© 2022, American Physical Society. All rights reserved.en
dc.subjectNear-band-gap electronic and optical properties of SixGe1-x-ySny alloysen
dc.subjectGe and GaAs substratesen
dc.titleElectronic and optical properties of SixGe1-x-ySny alloys lattice-matched to Geen
dc.typeArticle (peer-reviewed)en
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