CREST, Japan Science and Technology Agency , Kawaguchi , Saitama 332-0012 , Japan.
ACS Appl Mater Interfaces. 2019 Sep 18;11(37):34394-34398. doi: 10.1021/acsami.9b08797. Epub 2019 Sep 6.
Modern thermoelectric devices incline toward inexpensive, environmentally friendly, and CMOS-compatible materials, such as silicon. To improve the thermoelectric performance of silicon, researchers try to decrease its thermal conductivity using various nanostructuring methods. However, most of these methods have limited efficiency because they are costly and damaging for the internal structure of silicon. Here, we propose a cost-effective, large-area, and maskless nanofabrication method that creates external nanocones on the silicon surface while preserving its interior. Our experiments show that these nanocones reduce the thermal conductivity of thin silicon membranes by more than 40%. Using a modified Callaway-Holland model, we study how the thermal conductivity is affected by various phonon scattering processes in the 4-295 K temperature range. We conclude that the nanocones generate additional surface scattering, which causes the thermal conductivity reduction. The proposed nanocones and their simple fabrication method are promising for the planar thermoelectric devices based on silicon.
现代热电设备倾向于使用廉价、环保且与 CMOS 兼容的材料，例如硅。为了提高硅的热电性能，研究人员尝试使用各种纳米结构化方法来降低其热导率。然而，这些方法大多数效率有限，因为它们成本高且对硅的内部结构具有破坏性。在这里，我们提出了一种具有成本效益、大面积且无需掩模的纳米制造方法，可以在保持硅内部结构完整的情况下在其表面上制造外部纳米圆锥体。我们的实验表明，这些纳米圆锥体使薄硅膜的热导率降低了 40%以上。使用改进的 Callaway-Holland 模型，我们研究了在 4-295 K 温度范围内各种声子散射过程如何影响热导率。我们得出结论，纳米圆锥体产生了额外的表面散射，导致热导率降低。所提出的纳米圆锥体及其简单的制造方法有望用于基于硅的平面热电设备。
