Surface and Interface Engineering of Borophene Nanoelectronic Materials

The recent experimental realization of 2D boron (i.e., borophene) has spurred broad interest in its unique material attributes such as in-plane anisotropy, seamless phase intermixing, high mechanical strength and flexibility, massless Dirac fermions, and phonon-mediated superconductivity. The polymorphic nature of borophene, which is rooted in the rich bonding configurations among boron atoms, further distinguishes it from other 2D materials and offers an additional means for tailoring its material properties. However, the atomically thin nature of borophene presents a potentially even larger opportunity for modulating and exploiting its nanoelectronic properties through surface and interface engineering. Consequently, this proposal will employ atomically precise synthesis, functionalization, and characterization methods to understand and engineer surfaces and interfaces in borophene nanoelectronic materials. For example, covalent modification of borophene with hydrogen and organic adlayers holds promise for tailoring the surface chemistry of borophene and generating new phases of 2D boron including borophane (i.e., hydrogenated borophene) and organoborophene (i.e., organic functionalized borophene). Beyond surface functionalization, additional effort will be devoted to in situ encapsulation schemes that will allow borophene and its chemically modified analogues to be handled outside of ultrahigh vacuum environments. From the perspective of interface engineering, borophene growth will be pursued on additional surfaces beyond traditional silver substrates such as platinum, niobium, and alumina. In addition, borophene growth beyond the monolayer limit will be explored to enable the top borophene layer to be decoupled from the underlying substrate. By combining surface passivation and encapsulation with substrate decoupling, borophene will then be transferred to other substrates to facilitate its nanoelectronic characterization and integration. Throughout these studies, atomically precise imaging (e.g., scanning tunneling microscopy and spectroscopy), chemical spectroscopy (e.g., X-ray photoelectron and Raman spectroscopy), and charge transport measurements will reveal the fundamental chemistry and physics of borophene nanoelectronic materials. In this manner, this work will develop design rules for manipulating and integrating borophene into a range of electronic, optoelectronic, sensing, and quantum technologies with direct relevance for the Navy.