Ultralow Thermal Conductivity in Diamond-Like Semiconductors: Selective Scattering of Phonons from Antisite Defects
Ultralow Thermal Conductivity in Diamond-Like Semiconductors: Selective Scattering of Phonons from Antisite Defects
复制标题
类金刚石半导体中的超低导热率：反位缺陷选择性散射声子
DOI：
10.1021/acs.chemmater.8b00890
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发表时间：
2018
影响因子：
8.6
通讯作者：
Zevalkink, Alexandra
中科院分区：
文献类型：
--
作者：
Ortiz, Brenden R.;Peng, Wanyue;Gomes, Lídia C.;Gorai, Prashun;Zhu, Taishan;Smiadak, David M.;Snyder, G. Jeffrey;Stevanović, Vladan;Ertekin, Elif;Zevalkink, Alexandra
在这项工作中，我们发现在Cu 2 IIBIVTe 4（IIB：Zn，Cd，Hg）（IV：Si，Ge，Sn）组合物中含Hg的四元类金刚石半导体的晶格热导率非常低（在300 °C下<0.25 W/mK）。使用高温X射线衍射，共振超声光谱，和输运性质，我们发现的反位缺陷HgCu和CuHgon声子输运含汞系统内的关键作用。尽管汞和铜之间的化学差异，这些反位缺陷的高浓度出现从充满活力的接近的锌黄锡矿和锡铁矿阳离子图案。我们的声子计算表明，较重的IIB族元素不仅引入低的光学模式，但随后的反位缺陷也具有异常强大的点缺陷声子散射功率。散射强度源于由组成元素支持的根本不同的振动模式（例如，Hg和Cu）。尽管反位缺陷对热性能有显著影响，但反位缺陷不会对含Hg系统中的迁移率（在300 °C下>50 cm 2/（Vs））产生负面影响，导致在优化掺杂下Cu 2 HgGeTe 4和Cu 2 HgSnTe 4中的预测zT> 1.5。除了引入一种潜在的新p型热电材料外，这项工作还提供了（1）一种使用相变附近来增加点缺陷声子散射的策略，以及（2）一种通过廉价的声子计算来量化给定点缺陷功率的方法。
In this work, we discover anomalously low lattice thermal conductivity (<0.25 W/mK at 300 °C) in the Hg-containing quaternary diamond-like semiconductors within the Cu2IIBIVTe4(IIB: Zn, Cd, Hg) (IV: Si, Ge, Sn) set of compositions. Using high-temperature X-ray diffraction, resonant ultrasound spectroscopy, and transport properties, we uncover the critical role of the antisite defects HgCuand CuHgon phonon transport within the Hg-containing systems. Despite the differences in chemistry between Hg and Cu, the high concentration of these antisite defects emerges from the energetic proximity of the kesterite and stannite cation motifs. Our phonon calculations reveal that heavier group IIBelements not only introduce low-lying optical modes, but the subsequent antisite defects also possess unusually strong point defect phonon scattering power. The scattering strength stems from the fundamentally different vibrational modes supported by the constituent elements (e.g., Hg and Cu). Despite the significant impact on the thermal properties, antisite defects do not negatively impact the mobility (>50 cm2/(Vs) at 300 °C) in Hg-containing systems, leading to predictedzT> 1.5 in Cu2HgGeTe4and Cu2HgSnTe4under optimized doping. In addition to introducing a potentially new p-type thermoelectric material, this work provides (1) a strategy to use the proximity of phase transitions to increase point defect phonon scattering, and (2) a means to quantify the power of a given point defect through inexpensive phonon calculations.