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Band Anisotropy Generates Axis-Dependent Conduction Polarity of Mg3Sb2 and Mg3Bi2
Chemistry of Materials ( IF 7.2 ) Pub Date : 2024-02-07 , DOI: 10.1021/acs.chemmater.3c02970 Yosuke Goto 1 , Hidetomo Usui 2 , Masayuki Murata 1 , Joshua E. Goldberger 3 , Joseph P. Heremans 4 , Chul-Ho Lee 1
Chemistry of Materials ( IF 7.2 ) Pub Date : 2024-02-07 , DOI: 10.1021/acs.chemmater.3c02970 Yosuke Goto 1 , Hidetomo Usui 2 , Masayuki Murata 1 , Joshua E. Goldberger 3 , Joseph P. Heremans 4 , Chul-Ho Lee 1
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Materials that exhibit axis-dependent conduction polarity, meaning simultaneous p- and n-type conduction along different crystallographic directions, could be used to develop novel electronic and energy harvesting technologies, such as transverse thermoelectric devices. The present work demonstrates that layered Zintl-phase Mg3Sb2 and Mg3Bi2 possess this property. Single crystals of electron-doped Mg3Sb2 were found to show axis-dependent conduction polarity at low charge carrier concentrations (less than 1 × 1018 cm–3) based on the contribution of holes to conduction in the cross-plane direction. Mg3Bi2 also exhibited this same characteristic but over a wider range of doping with carrier concentrations greater than 1 × 1019 cm–3. This difference was attributed to the semimetallic band structure of Mg3Bi2. First-principles calculations established that axis-dependent conduction polarity appeared in these compounds as a consequence of band anisotropy that arises from the isotropic conduction band minimum and the anisotropic valence band maximum. Specifically, electron bands were primarily responsible for carrier conduction in the in-plane direction, whereas hole bands were dominant in the cross-plane direction. It is evident from these results that 122-type Zintl phases represent a new platform for the exploration of axis-dependent polarity based on band anisotropy engineering.
中文翻译：
能带各向异性产生 Mg3Sb2 和 Mg3Bi2 的轴相关传导极性
表现出轴相关传导极性的材料，即沿不同晶体方向同时进行 p 型和 n 型传导，可用于开发新型电子和能量收集技术，例如横向热电器件。目前的工作表明层状Zintl相Mg 3 Sb 2和Mg 3 Bi 2具有这种性质。电子掺杂的 Mg 3 Sb 2单晶被发现在低载流子浓度（小于 1 × 10 18 cm –3 ）下显示出轴相关的导电极性，这是基于空穴对横截面方向导电的贡献。Mg 3 Bi 2也表现出相同的特性，但掺杂范围更广，载流子浓度大于1 × 10 19 cm –3。这种差异归因于Mg 3 Bi 2的半金属能带结构。第一原理计算表明，由于各向同性导带最小值和各向异性价带最大值引起的能带各向异性，这些化合物中出现了轴相关的传导极性。具体而言，电子能带主要负责面内方向的载流子传导，而空穴能带在横面方向上占主导地位。从这些结果可以明显看出，122 型 Zintl 相代表了基于能带各向异性工程探索轴相关极性的新平台。
更新日期：2024-02-07
中文翻译：
能带各向异性产生 Mg3Sb2 和 Mg3Bi2 的轴相关传导极性
表现出轴相关传导极性的材料，即沿不同晶体方向同时进行 p 型和 n 型传导，可用于开发新型电子和能量收集技术，例如横向热电器件。目前的工作表明层状Zintl相Mg 3 Sb 2和Mg 3 Bi 2具有这种性质。电子掺杂的 Mg 3 Sb 2单晶被发现在低载流子浓度（小于 1 × 10 18 cm –3 ）下显示出轴相关的导电极性，这是基于空穴对横截面方向导电的贡献。Mg 3 Bi 2也表现出相同的特性，但掺杂范围更广，载流子浓度大于1 × 10 19 cm –3。这种差异归因于Mg 3 Bi 2的半金属能带结构。第一原理计算表明，由于各向同性导带最小值和各向异性价带最大值引起的能带各向异性，这些化合物中出现了轴相关的传导极性。具体而言，电子能带主要负责面内方向的载流子传导，而空穴能带在横面方向上占主导地位。从这些结果可以明显看出，122 型 Zintl 相代表了基于能带各向异性工程探索轴相关极性的新平台。
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