Using empirical pseudopotential theory, the direct (Γ) and indirect bandgaps (L and X) of unstrained crystalline SixGe1−x−ySny have been calculated over the entire xy composition range. The results are presented as energy-contour maps on ternary diagrams along with a ternary plot of the predicted lattice parameters. A group of 0.2 to 0.6 eV direct-gap SiGeSn materials is found for a variety of mid-infrared photonic applications. A set of “slightly indirect” SiGeSn alloys having a direct gap at 0.8 eV (but with a smaller L-Γ separation than in Ge) have been identified. These materials will function like Ge in various telecom photonic devices. Hetero-layered SiGeSn structures are described for infrared light emitters, amplifiers, photodetectors, and modulators (free carrier or Franz-Keldysh). We have examined in detail the optimized design space for mid-infrared SiGeSn-based multiple-quantum-well laser diodes, amplifiers, photodetectors, and quantum-confined Stark effect modulators.
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1 October 2012
Research Article|
October 04 2012
The direct and indirect bandgaps of unstrained SixGe1−x−ySny and their photonic device applications
P. Moontragoon;
P. Moontragoon
1
Department of Physics, Faculty of Science, Khon Kaen University
, Khon Kaen 40002, Thailand
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R. A. Soref;
R. A. Soref
2
Physics and Engineering Departments, University of Massachusetts at Boston
, Boston, Massachusetts 02125, USA
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Z. Ikonic
Z. Ikonic
3
School of Electronic and Electrical Engineering, University of Leeds
, Leeds LS2 9JT, United Kingdom
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J. Appl. Phys. 112, 073106 (2012)
Article history
Received:
May 23 2012
Accepted:
September 05 2012
Citation
P. Moontragoon, R. A. Soref, Z. Ikonic; The direct and indirect bandgaps of unstrained SixGe1−x−ySny and their photonic device applications. J. Appl. Phys. 1 October 2012; 112 (7): 073106. https://doi.org/10.1063/1.4757414
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