| AVS 63rd International Symposium & Exhibition | |
| 2D Materials Focus Topic | Tuesday Sessions |
| Session 2D+MI-TuM |
| Session: | Novel 2D Materials |
| Presenter: | Jakob Jørgensen, Aarhus University, Denmark |
| Authors: | J. Jørgensen, Aarhus University, Denmark L. Camilli, Technical University of Denmark A. Stoot, Technical University of Denmark A. Cassidy, Aarhus University, Denmark R. Balog, Aarhus University, Denmark J. Sadowski, Brookhaven National Laboratory P. Bøggild, Technical University of Denmark L. Hornekær, Aarhus University, Denmark |
| Correspondent: | Click to Email |
Two-dimensional (2D) materials have received enormous attention in the field of materials science and condensed matter physics in the last decade, with the ultimate goal being developing a new technology based on these materials [1]. A huge variety of promising 2D materials have been identified and the ability to combine these into complex structures is essential. For this reason the synthesis of 2D hetero-structures – i.e., structures resulting from the combination of two or more 2D materials – have been subject to an intense research effort over the last few years [2]. Here we report the first observation of spontaneous formation and self-assembly of graphene quantum dot superlattices embedded in a two-dimensional boron-carbon-nitrogen alloy.
By exposing a hot Ir(111) surface to carbon and boron-nitrogen precursor molecules it is found, using scanning tunnelling microscopy (STM), that the otherwise bulk-immiscible graphene and hexagonal boron nitride (hBN) materials can form a stress induced BCN alloy. Furthermore, pure-phase dislocations are found to co-exist with the alloy resulting in the bright triangular pattern of carbon enriched nanoribbons with a width of approximately 1 nm. Above a critical carbon concentration, an array of quantum dots (QD) of highly regular size and periodicity appears. Based on STM in combination with synchrotron x-ray photoemission spectroscopy (XPS) these QDs are determined consist of pure phase carbon, i.e. they are graphene QDs. These findings are consistent with well-established theories on elastic relaxations in ultrathin strained systems [3]. Thus our findings show a pathway to grow a highly periodic array of graphene quantum dots imbedded in a semiconducting BCN alloy.
In addition, using low energy electron microscopy (LEEM), the growth of the alloy structure is followed in-situ and diffraction experiments confirm the presence of the ordered quantum dot pattern even on a macroscopic level.
[1] A.C. Ferrari et al. Nanoscale 7, (2015) 4598
[2] H. Lim et al., Chemistry of Materials 26 (2014) 4891
[3] V. Ozolins et al. Phys. Rev. Lett. 88 (2002) 096101