Abstract

The compositional dependence of the lattice parameter in Ge1- ySny alloys has been determined from combined X-ray diffraction and Rutherford Backscattering (RBS) measurements of a large set of epitaxial films with compositions in the 0 < y < 0.14 range. In view of contradictory prior results, a critical analysis of this method has been carried out, with emphasis on nonlinear elasticity corrections and systematic errors in popular RBS simulation codes. The approach followed is validated by showing that measurements of Ge1- xSix films yield a bowing parameter θGeSi =-0.0253(30) Å, in excellent agreement with the classic work by Dismukes. When the same methodology is applied to Ge1- ySny alloy films, it is found that the bowing parameter θGeSn is zero within experimental error, so that the system follows Vegard's law. This is in qualitative agreement with ab initio theory, but the value of the experimental bowing parameter is significantly smaller than the theoretical prediction. Possible reasons for this discrepancy are discussed in detail.

Original languageEnglish (US)
Article number125702
JournalJournal of Applied Physics
Volume122
Issue number12
DOIs
StatePublished - Sep 28 2017

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backscattering
deviation
thin films
diffraction
x rays
systematic errors
lattice parameters
elastic properties
methodology
predictions
simulation

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

@article{cf847b2d31194c39ba4d6f138a441ecc,
title = "Deviations from Vegard's law in semiconductor thin films measured with X-ray diffraction and Rutherford backscattering: The Ge1- ySny and Ge1- xSix cases",
abstract = "The compositional dependence of the lattice parameter in Ge1- ySny alloys has been determined from combined X-ray diffraction and Rutherford Backscattering (RBS) measurements of a large set of epitaxial films with compositions in the 0 < y < 0.14 range. In view of contradictory prior results, a critical analysis of this method has been carried out, with emphasis on nonlinear elasticity corrections and systematic errors in popular RBS simulation codes. The approach followed is validated by showing that measurements of Ge1- xSix films yield a bowing parameter θGeSi =-0.0253(30) {\AA}, in excellent agreement with the classic work by Dismukes. When the same methodology is applied to Ge1- ySny alloy films, it is found that the bowing parameter θGeSn is zero within experimental error, so that the system follows Vegard's law. This is in qualitative agreement with ab initio theory, but the value of the experimental bowing parameter is significantly smaller than the theoretical prediction. Possible reasons for this discrepancy are discussed in detail.",
author = "Chi Xu and Senaratne, {Charutha L.} and Robert Culbertson and John Kouvetakis and Jose Menendez",
year = "2017",
month = "9",
day = "28",
doi = "10.1063/1.4996306",
language = "English (US)",
volume = "122",
journal = "Journal of Applied Physics",
issn = "0021-8979",
publisher = "American Institute of Physics Publising LLC",
number = "12",

}

TY - JOUR

T1 - Deviations from Vegard's law in semiconductor thin films measured with X-ray diffraction and Rutherford backscattering

T2 - The Ge1- ySny and Ge1- xSix cases

AU - Xu, Chi

AU - Senaratne, Charutha L.

AU - Culbertson, Robert

AU - Kouvetakis, John

AU - Menendez, Jose

PY - 2017/9/28

Y1 - 2017/9/28

N2 - The compositional dependence of the lattice parameter in Ge1- ySny alloys has been determined from combined X-ray diffraction and Rutherford Backscattering (RBS) measurements of a large set of epitaxial films with compositions in the 0 < y < 0.14 range. In view of contradictory prior results, a critical analysis of this method has been carried out, with emphasis on nonlinear elasticity corrections and systematic errors in popular RBS simulation codes. The approach followed is validated by showing that measurements of Ge1- xSix films yield a bowing parameter θGeSi =-0.0253(30) Å, in excellent agreement with the classic work by Dismukes. When the same methodology is applied to Ge1- ySny alloy films, it is found that the bowing parameter θGeSn is zero within experimental error, so that the system follows Vegard's law. This is in qualitative agreement with ab initio theory, but the value of the experimental bowing parameter is significantly smaller than the theoretical prediction. Possible reasons for this discrepancy are discussed in detail.

AB - The compositional dependence of the lattice parameter in Ge1- ySny alloys has been determined from combined X-ray diffraction and Rutherford Backscattering (RBS) measurements of a large set of epitaxial films with compositions in the 0 < y < 0.14 range. In view of contradictory prior results, a critical analysis of this method has been carried out, with emphasis on nonlinear elasticity corrections and systematic errors in popular RBS simulation codes. The approach followed is validated by showing that measurements of Ge1- xSix films yield a bowing parameter θGeSi =-0.0253(30) Å, in excellent agreement with the classic work by Dismukes. When the same methodology is applied to Ge1- ySny alloy films, it is found that the bowing parameter θGeSn is zero within experimental error, so that the system follows Vegard's law. This is in qualitative agreement with ab initio theory, but the value of the experimental bowing parameter is significantly smaller than the theoretical prediction. Possible reasons for this discrepancy are discussed in detail.

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U2 - 10.1063/1.4996306

DO - 10.1063/1.4996306

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