Plasmonic modes in metal structures are of great interest for optical applications. While metals such as Au and Ag are highly suitable for such applications at visible wavelengths, their high Drude losses limit their usefulness at mid-infrared wavelengths. Highly n-doped Ge_1−y Sn _y alloys are interesting possible alternative materials for plasmonic applications in this wavelength range. Here, we investigate the use of highly n-doped Ge_1−y Sn _y films grown directly on Si by molecular beam epitaxy with varying Sn-content from 0% up to 7.6% for plasmonic grating structures. We compare plasma wavelengths and relaxation times obtained from electrical and optical characterization. While theoretical considerations indicate that the decreasing effective mass with increasing Sn content in Ge_1−y Sn _y films could improve performance for plasmonic applications, our optical characterization results show that the utilization of Ge_1−y Sn _y films grown directly on Si is only beneficial if material quality can be improved.

金属结构中的等离子体模式对光学应用非常感兴趣。虽然金和银等金属非常适合可见光波长的此类应用，但它们的高德鲁德损耗限制了它们在中红外波长的应用。高度 n 掺杂的 Ge _{1− y} Sn _y合金是该波长范围内等离子体应用的有趣替代材料。在这里，我们研究了使用高度 n 掺杂的 Ge _{1− y} Sn _y 通过分子束外延直接在 Si 上生长的薄膜，对于等离子体光栅结构，Sn 含量从 0% 到 7.6% 不等。我们比较了从电学和光学表征中获得的等离子体波长和弛豫时间。虽然理论上的考虑表明，随着 Ge _{1− y} Sn _y薄膜中Sn 含量的增加，有效质量的降低可以提高等离子体应用的性能，但我们的光学表征结果表明，直接在 Si 上生长的 Ge _{1− y} Sn _y薄膜的利用率仅为如果可以提高材料质量，则是有益的。