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 (BiGe) 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，使其在热电领域的发展前景广阔。然而，GeTe 容易产生 Ge 空位，导致 p 型载流子浓度高，从而导致电子热导率升高和塞贝克系数低。本研究系统分析了 GeTe 及其合金的内禀和外禀缺陷，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 （BiGe） 取代 Ge 位点可产生较低的供体缺陷形成能量，有效降低了 GeTe 及其合金的 p 型载流子浓度。此外，由于价带最大值 （VBM） 的能级降低，与某些元素（如 Pb）形成合金化证明有利于降低 p 型载流子浓度。受此启发，筛选 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。Ba 和 Yb 合金 GeTe 的进一步计算证实了供体（有利）和受体（不利）缺陷的形成能变化。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，阐明了优化这些化合物中载流子浓度的可能策略。