Defect-engineering in graphene via focused ion beam for tailored van der Waals epitaxy of h-BN (ENGRAVE)

Ever since the discovery of graphene, other materials were found to be stable as single, two-dimensional (2D) layers, among which hexagonal boron nitride (h-BN) is of interest due to its large band gap. The vertical combination of h-BN and graphene offers novel possibilities for tuning electronic, optical and structural properties of the final 2D heterostructures. However, their potentially scalable fabrication via van der Waals epitaxy (vdWE), in which the 2D layers are grown on top of each other, is still at its infancy and the inert nature of graphene inhibits a homogeneous nucleation of h-BN, resulting in clustering and island formation.

The aim of the project ENGRAVE is to engineer chemically active defects in epitaxial graphene (EG) on SiC via focused ion beam to form stable nucleation sites during vdWE of h-BN. This will allow an unprecedented control over defect type and location in graphene, with the possibility to further manipulate the defects by post-processing. Through the respective expertise of the project partners the complex interactions between ion beams of various noble gases and graphene will be studied both, in theory and experiment, for a fundamental understanding of the defect formation in EG with the goal to optimize the nucleation of h-BN. 

The defined defects will not only be used to study the nucleation but also the coalescence of h-BN islands to form pristine 2D heterostructures in-between the defective nucleation centers. Ultimately this will allow the reproducible formation of graphene/h-BN heterostructures, which will be tailored into devices through appropriate placement of electronic contacts with regard to the artificial defects. The knowledge gained in this project based on experimental and computational characterization will provide valuable insight into defect formation and functionalization in graphene, which can be also extended to other 2D materials and to wafer scale.

The project is funded by Leibniz SAW under project number K335/2020. PDI's partner institutes are Helmholtz-Zentrum Dresden-Rossendorf and Ferdinand-Braun-Institut.