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Tunable optical gap at a fixed lattice constant in group-IV semiconductor alloys
V R D'Costa1, Y-Y Fang, J Tolle
1Department of Physics, Arizona State University, Tempe, Arizona 85287-1504, USA. vdcosta@asu.edu
New Germanium-Silicon-Tin (GeSiSn) alloys offer tunable light absorption for silicon photonics and photovoltaics. This breakthrough decouples electronic properties from lattice structure, enabling novel device applications.
Area of Science:
- Materials Science
- Semiconductor Physics
- Optoelectronics
Background:
- Silicon photonics is crucial for optical communication and computing.
- Group-IV alloys like Germanium-Silicon (GeSi) have limitations in tuning band gaps.
- Achieving tunable band gaps independently of lattice matching is a significant challenge.
Purpose of the Study:
- To demonstrate tunable direct absorption edges in novel Germanium-Silicon-Tin (GeSiSn) alloys.
- To explore the potential of these alloys in silicon photonics and photovoltaics.
- To understand the band gap behavior in a two-dimensional compositional space.
Main Methods:
- Epitaxial growth of strain-free ternary Ge_{1-x-y}Si_{x}Sn_{y} alloys on Germanium-buffered Silicon (Si).
- Characterization of optical absorption properties across a range of alloy compositions.
- Analysis of the compositional dependence of the direct band gap.
Main Results:
- Demonstrated a direct absorption edge tunable from 0.8 to 1.4 eV.
- Achieved decoupling of electronic structure and lattice parameter in group-IV alloys.
- Observed nonmonotonic band gap behavior explained by coexisting bowing parameters.
Conclusions:
- GeSiSn alloys present unprecedented opportunities for silicon photonics and advanced photovoltaic devices.
- The tunable band gap and decoupled properties are key advantages for future optoelectronic applications.
- Understanding bowing parameters is essential for precise band gap engineering in ternary alloys.
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