Fundamental band gap and direct-indirect crossover in Ge 1-x-ySixSny alloys

J. D. Gallagher; Chi Xu; Liying Jiang; John Kouvetakis; Jose Menendez

doi:10.1063/1.4829621

Fundamental band gap and direct-indirect crossover in Ge _1-x-ySi_xSn_y alloys

J. D. Gallagher, Chi Xu, Liying Jiang, John Kouvetakis, Jose Menendez

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Abstract

The Ge-like indirect band gap of Ge_1-x-ySi_xSn _y alloys has been determined over an extended y > x range using photoluminescence spectroscopy from films grown on Ge-buffered Si substrates. It is found that the compositional dependence of this transition can be fit with a bilinear expression of the form (in eV): E ind = (0.668 ± 0.008) + (0.67 ± 0.15) x - (1.77 ± 0.16) y. These energies are significantly below the prediction from a simple linear interpolation between Si, Ge, and α-Sn, revealing a large negative bowing in the compositional dependence similar to that found earlier for direct transitions. The direct-indirect crossover boundary is found to lie along the compositional line y = (0.062 ± 0.014) + (0.76 ± 0.23)x, which in the limit x → 0 agrees with earlier results for the binary Ge_1-ySn_y alloy.

Original language	English (US)
Article number	202104
Journal	Applied Physics Letters
Volume	103
Issue number	20
DOIs	https://doi.org/10.1063/1.4829621
State	Published - Nov 11 2013

ASJC Scopus subject areas

Physics and Astronomy (miscellaneous)

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10.1063/1.4829621

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title = "Fundamental band gap and direct-indirect crossover in Ge 1-x-ySixSny alloys",

abstract = "The Ge-like indirect band gap of Ge1-x-ySixSn y alloys has been determined over an extended y > x range using photoluminescence spectroscopy from films grown on Ge-buffered Si substrates. It is found that the compositional dependence of this transition can be fit with a bilinear expression of the form (in eV): E ind = (0.668 ± 0.008) + (0.67 ± 0.15) x - (1.77 ± 0.16) y. These energies are significantly below the prediction from a simple linear interpolation between Si, Ge, and α-Sn, revealing a large negative bowing in the compositional dependence similar to that found earlier for direct transitions. The direct-indirect crossover boundary is found to lie along the compositional line y = (0.062 ± 0.014) + (0.76 ± 0.23)x, which in the limit x → 0 agrees with earlier results for the binary Ge1-ySny alloy.",

author = "Gallagher, {J. D.} and Chi Xu and Liying Jiang and John Kouvetakis and Jose Menendez",

note = "Funding Information: This work was partially supported by the U.S. Air Force under contract DOD AFOSR FA9550-12-1-0208, and by the Air Force Research Laboratory under contract FA8650-13-C-1535.",

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doi = "10.1063/1.4829621",

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AU - Gallagher, J. D.

AU - Xu, Chi

AU - Jiang, Liying

AU - Kouvetakis, John

AU - Menendez, Jose

N1 - Funding Information: This work was partially supported by the U.S. Air Force under contract DOD AFOSR FA9550-12-1-0208, and by the Air Force Research Laboratory under contract FA8650-13-C-1535.

PY - 2013/11/11

Y1 - 2013/11/11

N2 - The Ge-like indirect band gap of Ge1-x-ySixSn y alloys has been determined over an extended y > x range using photoluminescence spectroscopy from films grown on Ge-buffered Si substrates. It is found that the compositional dependence of this transition can be fit with a bilinear expression of the form (in eV): E ind = (0.668 ± 0.008) + (0.67 ± 0.15) x - (1.77 ± 0.16) y. These energies are significantly below the prediction from a simple linear interpolation between Si, Ge, and α-Sn, revealing a large negative bowing in the compositional dependence similar to that found earlier for direct transitions. The direct-indirect crossover boundary is found to lie along the compositional line y = (0.062 ± 0.014) + (0.76 ± 0.23)x, which in the limit x → 0 agrees with earlier results for the binary Ge1-ySny alloy.

AB - The Ge-like indirect band gap of Ge1-x-ySixSn y alloys has been determined over an extended y > x range using photoluminescence spectroscopy from films grown on Ge-buffered Si substrates. It is found that the compositional dependence of this transition can be fit with a bilinear expression of the form (in eV): E ind = (0.668 ± 0.008) + (0.67 ± 0.15) x - (1.77 ± 0.16) y. These energies are significantly below the prediction from a simple linear interpolation between Si, Ge, and α-Sn, revealing a large negative bowing in the compositional dependence similar to that found earlier for direct transitions. The direct-indirect crossover boundary is found to lie along the compositional line y = (0.062 ± 0.014) + (0.76 ± 0.23)x, which in the limit x → 0 agrees with earlier results for the binary Ge1-ySny alloy.

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Fundamental band gap and direct-indirect crossover in Ge _1-x-ySi_xSn_y alloys

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