Extrinsic doping of Hg 2 GeTe 4 in the face of defect compensation and phase competition
Extrinsic doping of Hg 2 GeTe 4 in the face of defect compensation and phase competition
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Hg 2 GeTe 4 的外在掺杂面临缺陷补偿和相位竞争
DOI：
10.1039/d3tc00209h
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发表时间：
2023
影响因子：
6.4
通讯作者：
Toberer, Eric S.
中科院分区：
文献类型：
--
作者：
Porter, Claire E.;Qu, Jiaxing;Cielsielski, Kamil;Ertekin, Elif;Toberer, Eric S.
用于能源和信息应用的新兴半导体越来越多地由结构和化学复杂性比其一元和二元前身高得多的化合物组成。通常，由于面对固有缺陷时载流子浓度控制的挑战，这种复杂性限制了新材料的最终潜力。例如，有序空位化合物 Hg2GeTe4 中的固有缺陷对外在掺杂提出了具有挑战性的要求，以实现适合热电性能的载流子浓度水平。在这里，我们通过在不同合成条件下对 Hg2GeTe4 中的 16 种外在掺杂剂进行第一原理缺陷分析来应对这一挑战。其中八种掺杂剂（Au、Ag、Cu、Li、In、Ga、Zn、Sc）预计可将载流子浓度调整三个数量级。其余八种掺杂剂（Na、Mg、Y、La、Sb、Bi、Br、I）具有较高的形成能，预计影响最小。含有八种最有希望的掺杂剂的样品是由元素前体合成的，其传输特性测量值与预测值非常一致。与理论一致，简并 n 型掺杂被证明是不可用的，并且外在补偿缺陷被认为是主要障碍。发现p型掺杂剂是有效的；我们获得了 Ag 的简并载流子浓度和良好的热电性能（473 K 时 zT = 0.4）。将费米能级移动到价带边缘会降低 VHg−2 的浓度和相关的电离缺陷散射。这些观察结果强调了掺杂多元半导体时相互交织的依赖性网络，并强调了探索新材料时理论与实验合作的重要性。
Emerging semiconductors for energy and information applications increasingly consist of compounds with much higher structural and chemical complexity than their unary and binary predecessors. Often, such complexity has limited the ultimate potential of new materials due to challenges with carrier concentration control in the face of native defects. For example, native defects in ordered vacancy compound Hg2GeTe4 impose challenging requirements for extrinsic doping to achieve carrier concentration levels suitable for thermoelectric performance. Here, we address this challenge by performing first-principles defect analysis on 16 extrinsic dopants under different synthetic conditions in Hg2GeTe4. Eight of these dopants (Au, Ag, Cu, Li, In, Ga, Zn, Sc) are predicted to tune the carrier concentration over three orders of magnitude. The remaining eight dopants (Na, Mg, Y, La, Sb, Bi, Br, I) have high formation energy and are predicted to have minimal impact. Samples with the eight most promising dopants were synthesized from elemental precursors and their transport property measurements are in excellent agreement with predicted values. Consistent with theory, degenerate n-type doping proves to be unavailable, and extrinsic compensating defects are understood to be the primary barrier. The p-type dopants were found to be effective; we obtained degenerate carrier concentration with Ag and decent thermoelectric performance (zT = 0.4 at 473 K). Shifting the Fermi level to the valence band edge reduces the concentration of VHg−2 and associated ionized defect scattering. Such observations highlight the interwoven network of dependencies when doping multinary semiconductors, and emphasize the importance of theory-experimental collaborations when exploring new materials.