title: Phonon Engineering in Isotopically Disordered Silicon Nanowires.
abstract: The introduction of stable isotopes in the fabrication of semiconductor nanowires provides an additional degree of freedom to manipulate their basic properties, design an entirely new class of devices, and highlight subtle but important nanoscale and quantum phenomena. With this perspective, we report on phonon engineering in metal-catalyzed silicon nanowires with tailor-made isotopic compositions grown using isotopically enriched silane precursors (28)SiH4, (29)SiH4, and (30)SiH4 with purity better than 99.9%. More specifically, isotopically mixed nanowires (28)Si(x)(30)Si(1-x) with a composition close to the highest mass disorder (x ∼ 0.5) were investigated. The effect of mass disorder on the phonon behavior was elucidated and compared to that in isotopically pure (29)Si nanowires having a similar reduced mass. We found that the disorder-induced enhancement in phonon scattering in isotopically mixed nanowires is unexpectedly much more significant than in bulk crystals of close isotopic compositions. This effect is explained by a nonuniform distribution of (28)Si and (30)Si isotopes in the grown isotopically mixed nanowires with local compositions ranging from x = ∼0.25 to 0.70. Moreover, we also observed that upon heating, phonons in (28)Si(x)(30)Si(1-x) nanowires behave remarkably differently from those in (29)Si nanowires suggesting a reduced thermal conductivity induced by mass disorder. Using Raman nanothermometry, we found that the thermal conductivity of isotopically mixed (28)Si(x)(30)Si(1-x) nanowires is ∼30% lower than that of isotopically pure (29)Si nanowires in agreement with theoretical predictions.
authors.affiliation: †Department of Engineering Physics, Polytechnique Montréal, C. P. 6079, Succ. Centre-Ville, Montréal, Québec H3C 3A7, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Mukherjee
authors.affiliation: ‡Max Planck Institute of Microstructure Physics, Weinberg 2, D 06120 Halle (Saale), Germany.
authors.forename: U
authors.initials: U
authors.lastname: Givan
authors.affiliation: ‡Max Planck Institute of Microstructure Physics, Weinberg 2, D 06120 Halle (Saale), Germany.
authors.forename: S
authors.initials: S
authors.lastname: Senz
authors.affiliation: †Department of Engineering Physics, Polytechnique Montréal, C. P. 6079, Succ. Centre-Ville, Montréal, Québec H3C 3A7, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Bergeron
authors.affiliation: †Department of Engineering Physics, Polytechnique Montréal, C. P. 6079, Succ. Centre-Ville, Montréal, Québec H3C 3A7, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Francoeur
authors.affiliation: §Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Catalonia Spain.|△Institut Català de Nanociència i Nanotecnologia, ICN2, Campus UAB, 08193 Bellaterra, Catalonia, Spain.
authors.forename: M
authors.initials: M
authors.lastname: de la Mata
authors.affiliation: §Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Catalonia Spain.|∥Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Catalonia Spain.|△Institut Català de Nanociència i Nanotecnologia, ICN2, Campus UAB, 08193 Bellaterra, Catalonia, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Arbiol
authors.affiliation: ⊥Department of Applied Physics and Physico-Informatics, Keio University, Hiyoshi, Yokohama, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Sekiguchi
authors.affiliation: ⊥Department of Applied Physics and Physico-Informatics, Keio University, Hiyoshi, Yokohama, Japan.
authors.forename: K M
authors.initials: KM
authors.lastname: Itoh
authors.affiliation: #Department of Materials Science and Engineering Northwestern University Center for Atom-Probe Tomography, Northwestern University, Evanston, Illinois 60208-3108, United States.
authors.forename: D
authors.initials: D
authors.lastname: Isheim
authors.affiliation: #Department of Materials Science and Engineering Northwestern University Center for Atom-Probe Tomography, Northwestern University, Evanston, Illinois 60208-3108, United States.
authors.forename: D N
authors.initials: DN
authors.lastname: Seidman
authors.affiliation: †Department of Engineering Physics, Polytechnique Montréal, C. P. 6079, Succ. Centre-Ville, Montréal, Québec H3C 3A7, Canada.
authors.forename: O
authors.initials: O
authors.lastname: Moutanabbir
mesh_terms: D053770:Nanowires / Q000737:chemistry*; D060739:Phonons; D012821:Silanes / Q000737:chemistry; D012825:Silicon / Q000737:chemistry*
chemical_list: D012821:Silanes; D012825:Silicon
keywords: Nanowires; Raman spectroscopy; atom probe tomography; phonons; stable isotopes; thermal conductivity