GeTe exhibits excellent p-type medium-temperature thermoelectric properties with low toxicity and good mechanical characteristics, making it highly promising for development in the thermoelectric field. However, GeTe is prone to producing Ge vacancies, leading to high p-type carrier concentration, which results in elevated electronic thermal conductivity and a low Seebeck coefficient. This study systematically analyzes intrinsic and extrinsic defects in GeTe and its alloys, focusing on reducing p-type carrier concentration through first-principles calculations. The results reveal that substituting Ge-sites with Bi (Bi) yields lower donor defect formation energy, effectively reducing p-type carrier concentration of GeTe and its alloys compared to other elemental doping. Additionally, alloying with certain elements, such as Pb, proves favorable for decreased p-type carrier concentration due to lowered energy levels of valence band maximum (VBM). Inspired by this, screening divalent elements for alloying on Ge-sites reveals that Sr, Ba, Eu, and Yb substantially reduce the VBM of GeTe. Further calculations for Ba and Yb-alloyed GeTe confirm changes in formation energies for donor (favorable) and acceptor (unfavorable) defects. Our work provides a systematic investigation of intrinsic and various extrinsic doping defects in GeTe and its alloys, shedding light on possible strategies of optimizing carrier concentration in these compounds.

中文翻译：

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用于定制 GeTe 及其合金热电行为的缺陷工程和合金化策略

GeTe表现出优异的p型中温热电性能、低毒性和良好的机械特性，使其在热电领域极具发展前景。然而，GeTe容易产生Ge空位，导致p型载流子浓度较高，从而导致电子热导率升高和塞贝克系数较低。本研究系统分析了GeTe及其合金的内在和外在缺陷，重点是通过第一性原理计算降低p型载流子浓度。结果表明，与其他元素掺杂相比，用 Bi (Bi) 取代 Ge 位可产生较低的施主缺陷形成能，有效降低 GeTe 及其合金的 p 型载流子浓度。此外，由于价带最大值 (VBM) 能级降低，与某些元素（例如 Pb）进行合金化有利于降低 p 型载流子浓度。受此启发，筛选用于在 Ge 位点合金化的二价元素表明，Sr、Ba、Eu 和 Yb 显着降低了 GeTe 的 VBM。对 Ba 和 Yb 合金化 GeTe 的进一步计算证实了施主（有利）和受主（不利）缺陷的形成能的变化。我们的工作对 GeTe 及其合金中的内在和各种外在掺杂缺陷进行了系统研究，揭示了优化这些化合物中载流子浓度的可能策略。