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Yu Y, Zhou C, Ghosh T, Schön CF, Zhou Y, Wahl S, Raghuwanshi M, Kerres P, Bellin C, Shukla A, Cojocaru-Mirédin O, Wuttig M. Doping by Design: Enhanced Thermoelectric Performance of GeSe Alloys Through Metavalent Bonding. Adv Mater 2023; 35:e2300893. [PMID: 36920476 DOI: 10.1002/adma.202300893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/25/2023] [Indexed: 05/12/2023]
Abstract
Doping is usually the first step to tailor thermoelectrics. It enables precise control of the charge-carrier concentration and concomitant transport properties. Doping should also turn GeSe, which features an intrinsically a low carrier concentration, into a competitive thermoelectric. Yet, elemental doping fails to improve the carrier concentration. In contrast, alloying with Ag-V-VI2 compounds causes a remarkable enhancement of thermoelectric performance. This advance is closely related to a transition in the bonding mechanism, as evidenced by sudden changes in the optical dielectric constant ε∞ , the Born effective charge, the maximum of the optical absorption ε2 (ω), and the bond-breaking behavior. These property changes are indicative of the formation of metavalent bonding (MVB), leading to an octahedral-like atomic arrangement. MVB is accompanied by a thermoelectric-favorable band structure featuring anisotropic bands with small effective masses and a large degeneracy. A quantum-mechanical map, which distinguishes different types of chemical bonding, reveals that orthorhombic GeSe employs covalent bonding, while rhombohedral and cubic GeSe utilize MVB. The transition from covalent to MVB goes along with a pronounced improvement in thermoelectric performance. The failure or success of different dopants can be explained by this concept, which redefines doping rules and provides a "treasure map" to tailor p-bonded chalcogenides.
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Affiliation(s)
- Yuan Yu
- Institute of Physics (IA), RWTH Aachen University, Sommerfeldstraße 14, 52074, Aachen, Germany
| | - Chongjian Zhou
- State Key Laboratory of Solidification Processing, and Key Laboratory of Radiation Detection Materials and Devices, Ministry of Industry and Information Technology, Northwestern Polytechnical University, Xi'an, 710072, P. R. China
| | - Tanmoy Ghosh
- Institute of Physics (IA), RWTH Aachen University, Sommerfeldstraße 14, 52074, Aachen, Germany
| | - Carl-Friedrich Schön
- Institute of Physics (IA), RWTH Aachen University, Sommerfeldstraße 14, 52074, Aachen, Germany
| | - Yiming Zhou
- Institute of Physics (IA), RWTH Aachen University, Sommerfeldstraße 14, 52074, Aachen, Germany
| | - Sophia Wahl
- Institute of Physics (IA), RWTH Aachen University, Sommerfeldstraße 14, 52074, Aachen, Germany
| | - Mohit Raghuwanshi
- Institute of Physics (IA), RWTH Aachen University, Sommerfeldstraße 14, 52074, Aachen, Germany
| | - Peter Kerres
- Institute of Physics (IA), RWTH Aachen University, Sommerfeldstraße 14, 52074, Aachen, Germany
- PGI 10 (Green IT), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Christophe Bellin
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, UMR CNRS 7590, MNHN, 4 Place Jussieu, Paris, F-75005, France
| | - Abhay Shukla
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, UMR CNRS 7590, MNHN, 4 Place Jussieu, Paris, F-75005, France
| | - Oana Cojocaru-Mirédin
- Institute of Physics (IA), RWTH Aachen University, Sommerfeldstraße 14, 52074, Aachen, Germany
| | - Matthias Wuttig
- Institute of Physics (IA), RWTH Aachen University, Sommerfeldstraße 14, 52074, Aachen, Germany
- PGI 10 (Green IT), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
- Jülich - Aachen Research Alliance (JARA-FIT and JARA-HPC), RWTH Aachen University, 52056, Aachen, Germany
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Kerres P, Zhou Y, Vaishnav H, Raghuwanshi M, Wang J, Häser M, Pohlmann M, Cheng Y, Schön CF, Jansen T, Bellin C, Bürgler DE, Jalil AR, Ringkamp C, Kowalczyk H, Schneider CM, Shukla A, Wuttig M. Scaling and Confinement in Ultrathin Chalcogenide Films as Exemplified by GeTe. Small 2022; 18:e2201753. [PMID: 35491494 DOI: 10.1002/smll.202201753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Indexed: 06/14/2023]
Abstract
Chalcogenides such as GeTe, PbTe, Sb2 Te3 , and Bi2 Se3 are characterized by an unconventional combination of properties enabling a plethora of applications ranging from thermo-electrics to phase change materials, topological insulators, and photonic switches. Chalcogenides possess pronounced optical absorption, relatively low effective masses, reasonably high electron mobilities, soft bonds, large bond polarizabilities, and low thermal conductivities. These remarkable characteristics are linked to an unconventional bonding mechanism characterized by a competition between electron delocalization and electron localization. Confinement, that is, the reduction of the sample dimension as realized in thin films should alter this competition and modify chemical bonds and the resulting properties. Here, pronounced changes of optical and vibrational properties are demonstrated for crystalline films of GeTe, while amorphous films of GeTe show no similar thickness dependence. For crystalline films, this thickness dependence persists up to remarkably large thicknesses above 15 nm. X-ray diffraction and accompanying simulations employing density functional theory relate these changes to thickness dependent structural (Peierls) distortions, due to an increased electron localization between adjacent atoms upon reducing the film thickness. A thickness dependence and hence potential to modify film properties for all chalcogenide films with a similar bonding mechanism is expected.
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Affiliation(s)
- Peter Kerres
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
| | - Yiming Zhou
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
| | - Hetal Vaishnav
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
- Peter Grünberg Institute-JARA-Institute Energy-Efficient Information Technology (PGI-10), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Mohit Raghuwanshi
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
- Peter Grünberg Institute-JARA-Institute Energy-Efficient Information Technology (PGI-10), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Jiangjing Wang
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
- Center for Alloy Innovation and Design, Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Maria Häser
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
| | - Marc Pohlmann
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
| | - Yudong Cheng
- I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany
- Center for Alloy Innovation and Design, Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China
| | | | - Thomas Jansen
- Peter Grünberg Institute-Electronic Properties (PGI-6), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Christophe Bellin
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, UMR CNRS 7590, MNHN, Paris, F-75005, France
| | - Daniel E Bürgler
- Peter Grünberg Institute-Electronic Properties (PGI-6), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Abdur Rehman Jalil
- Peter Grünberg Institute-Semiconductor Nanoelectronics (PGI-6), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Christoph Ringkamp
- Peter Grünberg Institute-Semiconductor Nanoelectronics (PGI-6), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
| | - Hugo Kowalczyk
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, UMR CNRS 7590, MNHN, Paris, F-75005, France
| | - Claus M Schneider
- Peter Grünberg Institute-Electronic Properties (PGI-6), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
- JARA-FIT, RWTH Aachen University, 52056, Aachen, Germany
| | - Abhay Shukla
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, UMR CNRS 7590, MNHN, Paris, F-75005, France
| | - Matthias Wuttig
- Peter Grünberg Institute-JARA-Institute Energy-Efficient Information Technology (PGI-10), Forschungszentrum Jülich GmbH, 52428, Jülich, Germany
- JARA-FIT, RWTH Aachen University, 52056, Aachen, Germany
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Persch C, Müller MJ, Yadav A, Pries J, Honné N, Kerres P, Wei S, Tanaka H, Fantini P, Varesi E, Pellizzer F, Wuttig M. The potential of chemical bonding to design crystallization and vitrification kinetics. Nat Commun 2021; 12:4978. [PMID: 34404800 PMCID: PMC8371141 DOI: 10.1038/s41467-021-25258-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 07/29/2021] [Indexed: 11/05/2022] Open
Abstract
Controlling a state of material between its crystalline and glassy phase has fostered many real-world applications. Nevertheless, design rules for crystallization and vitrification kinetics still lack predictive power. Here, we identify stoichiometry trends for these processes in phase change materials, i.e. along the GeTe-GeSe, GeTe-SnTe, and GeTe-Sb2Te3 pseudo-binary lines employing a pump-probe laser setup and calorimetry. We discover a clear stoichiometry dependence of crystallization speed along a line connecting regions characterized by two fundamental bonding types, metallic and covalent bonding. Increasing covalency slows down crystallization by six orders of magnitude and promotes vitrification. The stoichiometry dependence is correlated with material properties, such as the optical properties of the crystalline phase and a bond indicator, the number of electrons shared between adjacent atoms. A quantum-chemical map explains these trends and provides a blueprint to design crystallization kinetics. Tailoring the crystallization kinetics of materials is important for targeting applications. Here the authors observe a remarkable dependence of crystallization and vitrification kinetics and attribute it to systematic bonding changes for a class of materials between metallic and covalent bonding.
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Affiliation(s)
- Christoph Persch
- I. Institute of Physics, Physics of Novel Materials, RWTH Aachen University, Aachen, Germany
| | - Maximilian J Müller
- I. Institute of Physics, Physics of Novel Materials, RWTH Aachen University, Aachen, Germany
| | - Aakash Yadav
- I. Institute of Physics, Physics of Novel Materials, RWTH Aachen University, Aachen, Germany
| | - Julian Pries
- I. Institute of Physics, Physics of Novel Materials, RWTH Aachen University, Aachen, Germany
| | - Natalie Honné
- I. Institute of Physics, Physics of Novel Materials, RWTH Aachen University, Aachen, Germany
| | - Peter Kerres
- I. Institute of Physics, Physics of Novel Materials, RWTH Aachen University, Aachen, Germany
| | - Shuai Wei
- I. Institute of Physics, Physics of Novel Materials, RWTH Aachen University, Aachen, Germany.,Department of Chemistry, Aarhus University, Aarhus C, Denmark
| | - Hajime Tanaka
- Institute of Industrial Science, University of Tokyo, Meguro-ku, Tokyo, Japan.,Research Center for Advanced Science and Technology, University of Tokyo, Meguro-ku, Tokyo, Japan
| | | | | | | | - Matthias Wuttig
- I. Institute of Physics, Physics of Novel Materials, RWTH Aachen University, Aachen, Germany. .,Jülich-Aachen Research Alliance (JARA FIT and JARA HPC), RWTH Aachen University, Aachen, Germany. .,PGI 10 (Green IT), Forschungszentrum Jülich GmbH, Jülich, Germany.
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