通过抑制表面介导退化增强SiGeSn的热稳定性
Enhanced thermal stability of SiGeSn by suppressing surface-mediated degradation
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中文总结 AI 辅助
本研究通过原位光谱椭圆偏振法发现，超薄氧化物覆盖层可抑制SiGeSn合金表面Sn传输，从而显著提升其热稳定性，为亚稳IV族合金在硅光子学中的集成提供了实用途径。
中文摘要 AI 辅助
SiGeSn合金是用于单片集成红外光子学的有前景的硅兼容半导体。然而，其亚稳性质限制了可用于生长后器件处理的热预算，且控制其热退化的机制仍未解决。在此，我们利用原位光谱椭圆偏振法（SE）在550 °C等温退火过程中研究了Si0.08Ge0.83Sn0.04合金的热稳定性。我们表明，添加超薄氧化物覆盖层在动力学上抑制了Sn与自由表面的交换，同时使体扩散路径基本不受影响。未覆盖薄膜在50分钟后发生相分离，伴随空洞形成、60%的厚度减少以及E2临界点（CP）跃迁的400 meV蓝移，这与通过表面偏析从探测体积中消耗替代性Sn一致。相比之下，氧化物覆盖薄膜在相同时间内表现出较小的成分变化（<1 at.% Sn）和光学位移（<20 meV），并抑制了空洞形成、应变松弛和合金分解。这种表面动力学控制还使得接触电阻率相对于退火未覆盖合金降低了25倍。这些结果确定了表面Sn传输是SiGeSn中的主要退化途径，并证明超薄氧化物覆盖层延长了亚稳IV族合金的热稳定性，为其集成到先进硅光子学和电子学平台提供了实用途径。
英文摘要
$\text{SiGeSn}$ alloys are promising silicon-compatible semiconductors for monolithic infrared photonics. However, their metastable nature limits the thermal budgets available for post-growth device processing, and the mechanisms governing their thermal degradation remain unresolved. Here, we investigate the thermal stability of $\text{Si}_{0.08}\text{Ge}_{0.83}\text{Sn}_{0.04}$ alloys using in situ spectroscopic ellipsometry (SE) during isothermal annealing at 550 °C. We show that adding an ultrathin oxide cap kinetically suppresses Sn exchange with the free surface while leaving bulk diffusion pathways largely unaffected. Uncapped films undergo phase separation after 50 min, accompanied by void formation, a 60% thickness reduction, and a 400 meV blueshift of the $E_{2}$ critical point (CP) transition, consistent with substitutional Sn depletion from the probed volume through surface segregation. In contrast, oxide-capped films exhibit a small compositional change (<1 at.% Sn) and optical shift (<20 meV) over the same period, with suppressed void formation, strain relaxation, and alloy decomposition. This surface-kinetic control additionally yields a 25-fold reduction in contact resistivity relative to annealed uncapped alloys. These results identify surface Sn transport as the dominant degradation pathway in SiGeSn and demonstrate that an ultrathin oxide cap extends the thermal stability of metastable group-IV alloys, providing a practical route toward their integration into advanced silicon photonic and electronic platforms.
发表机构
- École Polytechnique de Montréal（蒙特利尔高等理工学院）
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