{"title":"Defect engineering and alloying strategies for tailoring thermoelectric behavior in GeTe and its alloys","authors":"","doi":"10.1016/j.jmat.2024.01.007","DOIUrl":null,"url":null,"abstract":"<div><p>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<sub>Ge</sub>) 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.</p></div>","PeriodicalId":16173,"journal":{"name":"Journal of Materiomics","volume":"11 1","pages":"Article 100832"},"PeriodicalIF":8.4000,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2352847824000261/pdfft?md5=671504a7699189315e3b79974f90e081&pid=1-s2.0-S2352847824000261-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Materiomics","FirstCategoryId":"88","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2352847824000261","RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
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.
GeTe 具有优异的 p 型中温热电特性、低毒性和良好的机械特性,因此在热电领域极具开发前景。然而,GeTe 容易产生 Ge 空位,导致高 p 型载流子浓度,从而导致电子热导率升高和低塞贝克系数。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(铋)取代 Ge-位点可获得更低的供体缺陷形成能,从而有效降低 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(如铅)合金化有利于降低 p 型载流子浓度。受此启发,在筛选二价元素与 Ge 基底的合金时发现,Sr、Ba、Eu 和 Yb 能显著降低 GeTe 的 VBM。对钡和镱合金化 GeTe 的进一步计算证实了供体(有利)和受体(不利)缺陷形成能量的变化。我们的工作系统地研究了 GeTe 及其合金中的内在和各种外在掺杂缺陷,为优化这些化合物中载流子浓度的可能策略提供了启示。
期刊介绍:
The Journal of Materiomics is a peer-reviewed open-access journal that aims to serve as a forum for the continuous dissemination of research within the field of materials science. It particularly emphasizes systematic studies on the relationships between composition, processing, structure, property, and performance of advanced materials. The journal is supported by the Chinese Ceramic Society and is indexed in SCIE and Scopus. It is commonly referred to as J Materiomics.