9 Citations (Scopus)

Abstract

The dielectric functions of GeSn and GeSiSn alloys were measured in the 1-6 eV energy range using spectroscopic ellipsometry. The contributions from the E<inf>1</inf>, E<inf>1</inf> + Δ<inf>1</inf>, E<inf>0</inf>′, E<inf>2</inf>, and E<inf>1</inf>′ critical points in the joint density of electronic states were enhanced by computing numerical second derivatives of the measured dielectric function, and the resulting lineshapes were fitted with model expressions from which the critical point energies, amplitudes, broadenings, and phases were determined. A detailed analysis of the compositional dependence of the different transition energies is presented. By describing this dependence in terms of quadratic polynomials, the bowing parameter (quadratic coefficient) for each transition is determined. It is shown that the bowing parameters in the ternary alloy follow a distinct chemical trend, in which the ternary is well described in terms of bowing parameters for the underlying binary alloys, and these bowing parameters increase as a function of the size and electronegativity mismatch of the alloy constituents.

Original languageEnglish (US)
Pages (from-to)76-82
Number of pages7
JournalSolid-State Electronics
Volume110
DOIs
StatePublished - Aug 1 2015

Fingerprint

Bending (forming)
Optical transitions
optical transition
critical point
Electronegativity
Electronic density of states
Ternary alloys
Spectroscopic ellipsometry
energy
ternary alloys
Binary alloys
binary alloys
ellipsometry
polynomials
Polynomials
Derivatives
trends
coefficients
electronics

Keywords

  • Band structure
  • Ellipsometry
  • IR semiconductors
  • SiGeSn alloys

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry

Cite this

Compositional dependence of optical interband transition energies in GeSn and GeSiSn alloys. / Xu, Chi; Senaratne, Charutha L.; Kouvetakis, John; Menendez, Jose.

In: Solid-State Electronics, Vol. 110, 01.08.2015, p. 76-82.

Research output: Contribution to journalArticle

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title = "Compositional dependence of optical interband transition energies in GeSn and GeSiSn alloys",
abstract = "The dielectric functions of GeSn and GeSiSn alloys were measured in the 1-6 eV energy range using spectroscopic ellipsometry. The contributions from the E1, E1 + Δ1, E0′, E2, and E1′ critical points in the joint density of electronic states were enhanced by computing numerical second derivatives of the measured dielectric function, and the resulting lineshapes were fitted with model expressions from which the critical point energies, amplitudes, broadenings, and phases were determined. A detailed analysis of the compositional dependence of the different transition energies is presented. By describing this dependence in terms of quadratic polynomials, the bowing parameter (quadratic coefficient) for each transition is determined. It is shown that the bowing parameters in the ternary alloy follow a distinct chemical trend, in which the ternary is well described in terms of bowing parameters for the underlying binary alloys, and these bowing parameters increase as a function of the size and electronegativity mismatch of the alloy constituents.",
keywords = "Band structure, Ellipsometry, IR semiconductors, SiGeSn alloys",
author = "Chi Xu and Senaratne, {Charutha L.} and John Kouvetakis and Jose Menendez",
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T1 - Compositional dependence of optical interband transition energies in GeSn and GeSiSn alloys

AU - Xu, Chi

AU - Senaratne, Charutha L.

AU - Kouvetakis, John

AU - Menendez, Jose

PY - 2015/8/1

Y1 - 2015/8/1

N2 - The dielectric functions of GeSn and GeSiSn alloys were measured in the 1-6 eV energy range using spectroscopic ellipsometry. The contributions from the E1, E1 + Δ1, E0′, E2, and E1′ critical points in the joint density of electronic states were enhanced by computing numerical second derivatives of the measured dielectric function, and the resulting lineshapes were fitted with model expressions from which the critical point energies, amplitudes, broadenings, and phases were determined. A detailed analysis of the compositional dependence of the different transition energies is presented. By describing this dependence in terms of quadratic polynomials, the bowing parameter (quadratic coefficient) for each transition is determined. It is shown that the bowing parameters in the ternary alloy follow a distinct chemical trend, in which the ternary is well described in terms of bowing parameters for the underlying binary alloys, and these bowing parameters increase as a function of the size and electronegativity mismatch of the alloy constituents.

AB - The dielectric functions of GeSn and GeSiSn alloys were measured in the 1-6 eV energy range using spectroscopic ellipsometry. The contributions from the E1, E1 + Δ1, E0′, E2, and E1′ critical points in the joint density of electronic states were enhanced by computing numerical second derivatives of the measured dielectric function, and the resulting lineshapes were fitted with model expressions from which the critical point energies, amplitudes, broadenings, and phases were determined. A detailed analysis of the compositional dependence of the different transition energies is presented. By describing this dependence in terms of quadratic polynomials, the bowing parameter (quadratic coefficient) for each transition is determined. It is shown that the bowing parameters in the ternary alloy follow a distinct chemical trend, in which the ternary is well described in terms of bowing parameters for the underlying binary alloys, and these bowing parameters increase as a function of the size and electronegativity mismatch of the alloy constituents.

KW - Band structure

KW - Ellipsometry

KW - IR semiconductors

KW - SiGeSn alloys

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