Spectral phonon scattering from sub-10 nm surface roughness wavelengths in metal-assisted chemically etched Si nanowires

M. G. Ghossoub, K. V. Valavala, M. Seong, Bruno Azeredo, K. Hsu, J. S. Sadhu, P. K. Singh, S. Sinha

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

Frequency dependence in phonon surface scattering is a debated topic in fundamental phonon physics. Recent experiments and theory suggest such a phenomenon, but an independent agreement between the two remains elusive. We report low-temperature dependence of thermal conductivity in silicon nanowires fabricated using a two-step, metal-assisted chemical etch. By reducing etch rates down to 0.5 nm/s from the typical >100 nm/s, we report controllable roughening of nanowire surfaces and selectively focus on moderate roughness scales rather than the extreme scales investigated previously. This critically enables direct comparison with perturbation-based spectral scattering theory. Using experimentally characterized surface roughness, we show that a multiple scattering theory provides excellent agreement and explanation of the observed low-temperature dependence of rough surface nanowires. The theory does not employ any fitting parameters. A 5-10 nm roughness correlation length is typical in metal-assisted chemical etching and resonantly scatters dominant phonons in silicon, leading to the observed ∼T1.6-2.4 behavior. Our work provides fundamental and quantitative insight into spectral phonon scattering from rough surfaces. This advances applications of nanowires in thermoelectric energy conversion.

Original languageEnglish (US)
Pages (from-to)1564-1571
Number of pages8
JournalNano Letters
Volume13
Issue number4
DOIs
StatePublished - Apr 10 2013
Externally publishedYes

Fingerprint

Phonons
Nanowires
Phonon scattering
surface roughness
nanowires
Surface roughness
Metals
Wavelength
Silicon
scattering
wavelengths
metals
Thermoelectric energy conversion
roughness
Thermal Conductivity
Surface scattering
temperature dependence
Temperature
Multiple scattering
Physics

Keywords

  • frequency dependence
  • phonon
  • Silicon nanowire
  • surface scattering
  • thermal conductivity

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Mechanical Engineering
  • Medicine(all)

Cite this

Spectral phonon scattering from sub-10 nm surface roughness wavelengths in metal-assisted chemically etched Si nanowires. / Ghossoub, M. G.; Valavala, K. V.; Seong, M.; Azeredo, Bruno; Hsu, K.; Sadhu, J. S.; Singh, P. K.; Sinha, S.

In: Nano Letters, Vol. 13, No. 4, 10.04.2013, p. 1564-1571.

Research output: Contribution to journalArticle

Ghossoub, MG, Valavala, KV, Seong, M, Azeredo, B, Hsu, K, Sadhu, JS, Singh, PK & Sinha, S 2013, 'Spectral phonon scattering from sub-10 nm surface roughness wavelengths in metal-assisted chemically etched Si nanowires', Nano Letters, vol. 13, no. 4, pp. 1564-1571. https://doi.org/10.1021/nl3047392
Ghossoub, M. G. ; Valavala, K. V. ; Seong, M. ; Azeredo, Bruno ; Hsu, K. ; Sadhu, J. S. ; Singh, P. K. ; Sinha, S. / Spectral phonon scattering from sub-10 nm surface roughness wavelengths in metal-assisted chemically etched Si nanowires. In: Nano Letters. 2013 ; Vol. 13, No. 4. pp. 1564-1571.
@article{1c2d902e54d24ee398d0f6728064f3b9,
title = "Spectral phonon scattering from sub-10 nm surface roughness wavelengths in metal-assisted chemically etched Si nanowires",
abstract = "Frequency dependence in phonon surface scattering is a debated topic in fundamental phonon physics. Recent experiments and theory suggest such a phenomenon, but an independent agreement between the two remains elusive. We report low-temperature dependence of thermal conductivity in silicon nanowires fabricated using a two-step, metal-assisted chemical etch. By reducing etch rates down to 0.5 nm/s from the typical >100 nm/s, we report controllable roughening of nanowire surfaces and selectively focus on moderate roughness scales rather than the extreme scales investigated previously. This critically enables direct comparison with perturbation-based spectral scattering theory. Using experimentally characterized surface roughness, we show that a multiple scattering theory provides excellent agreement and explanation of the observed low-temperature dependence of rough surface nanowires. The theory does not employ any fitting parameters. A 5-10 nm roughness correlation length is typical in metal-assisted chemical etching and resonantly scatters dominant phonons in silicon, leading to the observed ∼T1.6-2.4 behavior. Our work provides fundamental and quantitative insight into spectral phonon scattering from rough surfaces. This advances applications of nanowires in thermoelectric energy conversion.",
keywords = "frequency dependence, phonon, Silicon nanowire, surface scattering, thermal conductivity",
author = "Ghossoub, {M. G.} and Valavala, {K. V.} and M. Seong and Bruno Azeredo and K. Hsu and Sadhu, {J. S.} and Singh, {P. K.} and S. Sinha",
year = "2013",
month = "4",
day = "10",
doi = "10.1021/nl3047392",
language = "English (US)",
volume = "13",
pages = "1564--1571",
journal = "Nano Letters",
issn = "1530-6984",
publisher = "American Chemical Society",
number = "4",

}

TY - JOUR

T1 - Spectral phonon scattering from sub-10 nm surface roughness wavelengths in metal-assisted chemically etched Si nanowires

AU - Ghossoub, M. G.

AU - Valavala, K. V.

AU - Seong, M.

AU - Azeredo, Bruno

AU - Hsu, K.

AU - Sadhu, J. S.

AU - Singh, P. K.

AU - Sinha, S.

PY - 2013/4/10

Y1 - 2013/4/10

N2 - Frequency dependence in phonon surface scattering is a debated topic in fundamental phonon physics. Recent experiments and theory suggest such a phenomenon, but an independent agreement between the two remains elusive. We report low-temperature dependence of thermal conductivity in silicon nanowires fabricated using a two-step, metal-assisted chemical etch. By reducing etch rates down to 0.5 nm/s from the typical >100 nm/s, we report controllable roughening of nanowire surfaces and selectively focus on moderate roughness scales rather than the extreme scales investigated previously. This critically enables direct comparison with perturbation-based spectral scattering theory. Using experimentally characterized surface roughness, we show that a multiple scattering theory provides excellent agreement and explanation of the observed low-temperature dependence of rough surface nanowires. The theory does not employ any fitting parameters. A 5-10 nm roughness correlation length is typical in metal-assisted chemical etching and resonantly scatters dominant phonons in silicon, leading to the observed ∼T1.6-2.4 behavior. Our work provides fundamental and quantitative insight into spectral phonon scattering from rough surfaces. This advances applications of nanowires in thermoelectric energy conversion.

AB - Frequency dependence in phonon surface scattering is a debated topic in fundamental phonon physics. Recent experiments and theory suggest such a phenomenon, but an independent agreement between the two remains elusive. We report low-temperature dependence of thermal conductivity in silicon nanowires fabricated using a two-step, metal-assisted chemical etch. By reducing etch rates down to 0.5 nm/s from the typical >100 nm/s, we report controllable roughening of nanowire surfaces and selectively focus on moderate roughness scales rather than the extreme scales investigated previously. This critically enables direct comparison with perturbation-based spectral scattering theory. Using experimentally characterized surface roughness, we show that a multiple scattering theory provides excellent agreement and explanation of the observed low-temperature dependence of rough surface nanowires. The theory does not employ any fitting parameters. A 5-10 nm roughness correlation length is typical in metal-assisted chemical etching and resonantly scatters dominant phonons in silicon, leading to the observed ∼T1.6-2.4 behavior. Our work provides fundamental and quantitative insight into spectral phonon scattering from rough surfaces. This advances applications of nanowires in thermoelectric energy conversion.

KW - frequency dependence

KW - phonon

KW - Silicon nanowire

KW - surface scattering

KW - thermal conductivity

UR - http://www.scopus.com/inward/record.url?scp=84876053671&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84876053671&partnerID=8YFLogxK

U2 - 10.1021/nl3047392

DO - 10.1021/nl3047392

M3 - Article

C2 - 23464810

AN - SCOPUS:84876053671

VL - 13

SP - 1564

EP - 1571

JO - Nano Letters

JF - Nano Letters

SN - 1530-6984

IS - 4

ER -