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
N1 - Funding Information:
This work was supported by the National Science Foundation under Grant No. DMR-1309090. We acknowledge the use of facilities at the LeRoy Eyring Center for Solid State Science.
Publisher Copyright:
© 2017 Author(s).
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
M3 - Article
AN - SCOPUS:85030181250
SN - 0021-8979
VL - 122
JO - Journal of Applied Physics
JF - Journal of Applied Physics
IS - 12
M1 - 125702
ER -