Research breakthrough: a new method for substituting atoms in 2D materials
”We discovered a new method for substituting atoms in 2D materials by foreign elements. The substitution process can be thought of as slowly propagating crack in the pristine starting material, but instead of breaking the material in half the crack is also simultaneously filled with foreign elements that we introduced onto the material surface. Successful substitution was confirmed using high-resolution electron microscopy, and the process was modeled using quantum mechanical simulations”, Academy research fellow Hannu-Pekka Komsa of the Microelectronics Research Unit, University of Oulu, sums up the results of the research.
The results were published in the recent issue of Advanced Materials with the title Formation of Highly Doped Nanostripes in 2D Transition Metal Dichalcogenides via a Dislocation Climb Mechanism. The research article includes authors from Finland, Germany, Taiwan and Japan.
Together with Hannu-Pekka Komsa researchers Yung‐Chang Lin, Jeyakumar Karthikeyan, Yao‐Pang Chang, Shisheng Li, Silvan Kretschmer, Po‐Wen Chiu, Arkady V. Krasheninnikov and Kazu Suenaga found that their new method yields extremely high density of dopants organized in linear stripes, while still retaining high crystalline quality of the material - something that would be difficult to achieve by other methods.
"This method can only work in the case of 2D materials, since the "crack" is always accessible to the substituting species from the top of the sheet. This is not possible in bulk materials and probably explains why such a method has not been discovered previously”, Komsa says enthusiastically.
The results are expected to have an impact on many novel applications of 2D materials.
“Dopants can act as catalytically active sites, and thus 2D materials with large surface area, and high density of dopants is particularly promising for catalysis applications. In electronics, the presence of pristine material between the dopant stripes can be used for achieving atomically thin conducting channels. Finally, materials with lines of ferromagnetically coupled impurities would be of high interest in the context of spintronic applications”, Komsa muses.