Periodic Nanoslot Patterns as an Effective Approach to Improving the Thermoelectric Performance of Thin Films
Periodic Nanoslot Patterns as an Effective Approach to Improving the Thermoelectric Performance of Thin Films
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DOI：
10.1103/physrevapplied.13.064020
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发表时间：
2020-06-08
影响因子：
4.6
通讯作者：
Xiao, Yue
中科院分区：
文献类型：
--
作者：
Hao, Qing;Xiao, Yue
在热电应用方面，具有周期性圆孔结构的硅薄膜由于硅的廉价和地球资源丰富而得到了广泛的研究。在这项工作中，研究了不同的周期性纳米多孔图案的潜在热电效益，即，具有周期性纳米槽的Si薄膜。在这样的结构内部，相邻纳米槽之间的颈部用作纳米限制以抑制声子输运，导致晶格热导率显著降低。当颈部宽度仍然大于多数载流子的平均自由程时，可以保持块状电子输运，从而可以增强热电ZT。对于这些多孔薄膜的热设计，一个简单但准确的分析模型的基础上的平均自由程修改的特征长度推导出，并用于预测其热电性能。对于颈宽减小到5nm的重掺杂Si薄膜，计算得到的ZT在1100K时可达0.58。所提出的纳米槽图案可以扩展到一般的薄膜和原子厚的材料，以调整它们的输运性质。
For thermoelectric applications, thermoelectric Si thin films with periodic circular pores have been intensively studied because of the low price and earth abundance of Si. In this work, a different periodic nanoporous pattern is investigated for its potential thermoelectric benefit, i.e., a Si thin film with periodic nanoslots. Inside such structures, the neck between adjacent nanoslots functions as the nanorestriction to suppress the phonon transport, leading to a dramatically reduced lattice thermal conductivity. When the neck width is still longer than the mean free paths of majority charge carriers, bulklike electron transport can be maintained so that the thermoelectric ZT can be enhanced. For the thermal designs of these porous thin films, a simple but accurate analytical model based on the mean-free-path modification with a characteristic length is derived and is used to predict their thermoelectric properties. For heavily doped Si films with the neck width reduced to 5 nm, the computed ZT can reach 0.58 at 1100 K. The proposed nanoslot pattern can be extended to general thin films and atomic thick materials to tune their transport properties.