Tuning valley degeneracy with band inversion
Tuning valley degeneracy with band inversion
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通过能带反转调节谷简并性
DOI：
10.1039/d1ta08379a
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发表时间：
2022
影响因子：
11.9
通讯作者：
Snyder, G. Jeffrey
中科院分区：
文献类型：
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作者：
Toriyama, Michael Y.;Brod, Madison K.;Gomes, Lídia C.;Bipasha, Ferdaushi A.;Assaf, Badih A.;Ertekin, Elif;Snyder, G. Jeffrey
谷简并性是电子结构的一个关键特征，有利于材料的热电性能。尽管最近的研究声称高谷简并可以通过倒转能带实现，但我们使用第一性原理计算和 k·p 微扰理论对岩盐 IV-VI 化合物的分析表明，单纯的能带反转不足以实现高谷简并；相反，必须将能带反转到一个临界程度才能产生多个载流子袋。所谓的“能带反转参数”被形式化为一种化学可调特性，提供了一种在具有反转能带的化合物中实现高谷简并性的设计路线。我们预测岩盐 IV-VI 化合物的谷简并度可以从 NV = 4 增加到 NV = 24，这可能导致热电品质因数 zT 相应增加。
Valley degeneracy is a key feature of the electronic structure that benefits the thermoelectric performance of a material. Despite recent studies which claim that high valley degeneracy can be achieved with inverted bands, our analysis of rock-salt IV–VI compounds using first-principles calculations and k·p perturbation theory demonstrates that mere band inversion is an insufficient condition for high valley degeneracy; rather, there is a critical degree to which the bands must be inverted to induce multiple carrier pockets. The so-called “band inversion parameter” is formalized as a chemically-tunable property, offering a design route to achieving high valley degeneracy in compounds with inverted bands. We predict that the valley degeneracy of rock-salt IV–VI compounds can be increased from NV = 4 to NV = 24, which could result in a corresponding increase in the thermoelectric figure of merit zT.