Informationsquelle: Fakultät für Physik

Am 27. Mai 2020 machten der Forscher Liu Kaihui, der Akademiker Wang Enge von der Fakultät für Physik der Universität Peking, der Akademiker Yu Dapeng von der Südlichen Universität für Wissenschaft und Technologie und Professor Ding Feng vom Ulsan-Institut für Wissenschaft und Technologie in Südkorea wichtig Fortschritte bei der Herstellung von Einkristall-Kupferfolien mit hohem Index. The research team creatively proposed the "variation and inheritance" growth mechanism regulated by the interface of the crystal surface, for the first time in the world to realize the manufacture of the most complete and largest size high-index single crystal copper foil library. Related research results were published online in the journal Nature with the title "Seeded growth of large single-crystal copper foils with high-index facets".

Copper plays an extremely important role in the modern information society and is widely used in key fields such as electrical, electronic, communications, and national defense. However, the commercial copper currently on the market is basically polycrystalline copper, and various defects in it cause the efficiency of electron and phonon transport to be greatly reduced. In theory, single-crystal copper with a perfect crystal structure can maximize the intrinsic electrical and thermal performance of copper, and it is expected to have an important impact in the direction of low-loss, high-heat dissipation power and electronic device applications. In addition, with the rise of two-dimensional material research in recent years, copper has been widely used in the epitaxial preparation of two-dimensional single crystal materials. A single crystal copper foil substrate with various index crystal planes is the basis for the epitaxial growth of two-dimensional single crystal materials with different structures. Therefore, the preparation of single crystal copper foil with large size and multiple index crystal planes is a scientific and technical problem to be solved urgently in industry and scientific research.

In der Materialwissenschaft kann Einkristall-Kupferfolie gemäß dem Kristallebenenindex in zwei Kategorien unterteilt werden: Kristallebene mit niedrigem Index und Kristallebene mit hohem Index. Wie in Abbildung 1 gezeigt, gibt es nur drei Arten von Kristallebenen mit niedrigem Index: Cu (001), Cu (011) und Cu (111), während es theoretisch unbegrenzte Arten von Kristallebenen mit hohem Index gibt. Seit 2016 haben Liu Kaihui und Mitarbeiter eine Reihe von Fortschritten bei der Erforschung von Kupfer-Einkristallen mit niedrigem Index erzielt: ultraschnelle epitaktische Herstellung von Ein-Meter-Graphen-Einkristallen auf Einkristall-Cu (111) (Nature Chemistry 2019, 11, 730; Science Bulletin 2017, 62, 1074; Nature Nanotechnology 2016, 11, 930); Zweidimensionale hexagonale Bornitrid-Einkristallepitaxie im Dezimeterbereich auf dem benachbarten Cu (110) -Einkristall (Nature 2019, 570, 91). Verglichen mit der Kristallebene mit niedrigem Index kann die Kupferfolie mit hoher Indexebene eine reichere Oberflächenstruktur liefern, was die Arten der epitaktischen Herstellung zweidimensionaler Materialsysteme erheblich erweitern kann. Das herkömmliche Glühverfahren kann jedoch normalerweise nur den Cu (111) -Einkristall mit der niedrigsten Oberflächenenergie erhalten, und die Kristallebene mit hohem Index ist in der Thermodynamik und Kinetik nicht dominant, und seine Kontrollvorbereitung ist äußerst schwierig.

In response to this problem, the research team developed a new annealing technology to achieve thermodynamic and kinetic control of the copper foil recrystallization process (Figure 2a). Different from the traditional annealing process, a layer of oxide can be formed on the surface of the copper foil through the designed pre-oxidation process. The formation of the interface between copper and copper oxide makes the traditional "minimum surface energy principle" no longer the main driving force for the formation of crystal planes. , So as to greatly increase the formation probability of high-index crystal plane "nucleus"; through the designed reducing atmosphere annealing process to eliminate the dynamic grain boundary, the abnormal growth of the high-index crystal plane "nucleus" can be achieved, thereby preparing A4 paper The size of the high-index crystal plane single crystal has more than 30 types of crystal planes (Figure 2b-c). At the same time, using the prepared single crystal copper foil as a "seed crystal" can induce the conversion of polycrystalline copper foil into a single crystal having the same crystal orientation as the "seed crystal", thereby realizing a large-size single crystal copper foil with a specific crystal plane Oriented "replication" manufacturing of single crystal copper ingots. In addition, this method is universal for the preparation of other single crystal metal foils.

This research achievement is the first to realize the controllable preparation of the single crystal copper foil library with the largest size and the most complete crystal face index in the world. In single crystal metal research, two-dimensional material growth, surface interface catalysis, low-loss electrical transmission, high frequency The fields of circuit boards and high heat sinks are of pioneering significance.

Wu Muhong, Zhang Zhibin, Xu Xiaozhi and Zhang Zhihong are the co-first authors of the paper, and Liu Kaihui, Ding Feng, Yu Dapeng and Wang Enge are the corresponding authors. The research results have been strongly supported by the Natural Science Foundation of China, the Ministry of Science and Technology, Beijing Science and Technology Commission and other related projects, Peking University State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, Collaborative Innovation Center for Quantum Matter Science and Electron Microscope Laboratory, etc. .