Reduction of Thermal Conductivity in Nanowires by Combined Engineering of Crystal Phase and Isotope Disorder
Mukherjee, Samik (Polytechnique Montréal. Département de génie physique)
Givan, Uri (Max Planck Institute of Microstructure Physics)
Senz, Stephan (Max Planck Institute of Microstructure Physics)
De La Mata, Maria (Institut Català de Nanociència i Nanotecnologia)
Arbiol i Cobos, Jordi (Institut Català de Nanociència i Nanotecnologia)
Moutanabbir, Oussama (École Polytechnique de Montréal. Department of Engineering Physics)

Data:	2018
Resum:	Nanowires are a versatile platform to investigate and harness phonon and thermal transport phenomena in nanoscale systems. With this perspective, we demonstrate herein the use of crystal phase and mass disorder as effective degrees of freedom to manipulate the behavior of phonons and control the flow of local heat in silicon nanowires. The investigated nanowires consist of isotopically pure and isotopically mixed nanowires bearing either a pure diamond cubic or a cubic-rhombohedral polytypic crystal phase. The nanowires with tailor-made isotopic compositions were grown using isotopically enriched silane precursors SiH, SiH, and SiH with purities better than 99. 9%. The analysis of polytypic nanowires revealed ordered and modulated inclusions of lamellar rhombohedral silicon phases toward the center in otherwise diamond-cubic lattice with negligible interphase biaxial strain. Raman nanothermometry was employed to investigate the rate at which the local temperature of single suspended nanowires evolves in response to locally generated heat. Our analysis shows that the lattice thermal conductivity in nanowires can be tuned over a broad range by combining the effects of isotope disorder and the nature and degree of polytypism on phonon scattering. We found that the thermal conductivity can be reduced by up to ∼40% relative to that of isotopically pure nanowires, with the lowest value being recorded for the rhombohedral phase in isotopically mixed Si Si nanowires with composition close to the highest mass disorder (x ∼ 0. 5). These results shed new light on the fundamentals of nanoscale thermal transport and lay the groundwork to design innovative phononic devices.
Ajuts:	Agència de Gestió d'Ajuts Universitaris i de Recerca 2014/SGR-1638 Ministerio de Economía y Competitividad ENE2017-85087-C3-3-R Ministerio de Economía y Competitividad SEV-2013-0295
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Thermal conductivity ; Stable isotope engineering ; Polytypic crystal phase ; Silicon nanowires ; Phonon engineering ; Raman nanothermometry ; Strain mapping
Publicat a:	Nano letters, Vol. 18, Issue 5 (May 2018) , p. 3066-3075, ISSN 1530-6992

DOI: 10.1021/acs.nanolett.8b00612

Postprint 28 p, 1.9 MB

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