In an initial stage, the synthesis of hBN was achieved on Ir(111) and Cu(111) via chemical vapor deposition (CVD) of borazine. In parallel, the Fellow and co-workers realized that diborane, originating from byproducts of borazine, can be used to grow high-quality borophene on Ir(111). That represented a breakthrough in the field of 2D materials growth, as it was the first time for an elemental atomically-thin material beyond graphene to be grown by CVD. Consequently, and in order to maximize the outcome of the action, efforts were redirected to comprehensively study borophene's properties, and to exploit the newly-developed CVD method for the growth and functionalization of 2D materials beyond the initially proposed hBN.
Thereafter, the diborane-based CVD method was used to synthesize borophene on Cu(111), and diverse nanoarchitectures formed by borophene and hBN. In particular, lateral heterostructures in which borophene and hBN form atomically precise interfaces, and vertical van der Waals heterostructures in which hBN covers borophene and protects it from immediate oxidation. The Fellow characterized the novel heterostructures by techniques with atomic precision (scanning tunneling microscopy and spectroscopy) and surface-average sensitivity (low energy electron diffraction and x-ray photoelectron spectroscopy), which provided insight into the structural, electronic and chemical properties of the novel heterostructures. This part of the action led to the publication of a research article in Science Advances, filing of a patent, several presentations in front of national and international audiences, and the defence of a MSc theses.
In parallel, the potential of hBN to support the fabrication of ordered structures at the nanoscale, inspired by the strong tradition of the host group in this sort of studies. Specifically, hBN was synthesized by CVD of borazine on Ir(100), finding that it naturally develops a moiré corrugation of unconventional 2-fold symmetry. Interestingly, the Fellow and co-workers showed that this can be used to template the self-assembly and orientation of small organic molecules. It was demonstrated for the case of archetypal pentacene, and characterized by the techniques mentioned above, complemented by a photoemission tomography study performed using synchrotron radiation. This part of the action led to the preparation of a manuscript, and the defence of a MSc theses.
In pursuit of creating novel functional nanoarchitectures made of 2D materials, CVD of borane tetrahydrofuran on Ir(111) was explored in the later stages of the action. This was shown to be a successful strategy to fabricate 2D arrays of boron substitutional heteroatoms embedded in an exemplary 2D material like graphene. Through a combined experimental and theoretical effort, the Fellow and collaborators provided a complete description and rationalization of the heteroatom distribution, bonding configurations, interfacial interaction with Ir(111) and impact on graphene's electronic properties. The investigations carried in this last part of the action were summarized in a research article.
