Synthesis of Semiconducting Graphene Nanoribbons on Germanium for Next-Generation Nanoelectronics

Arrays of aligned semiconducting graphene nanoribbons with sub-5-nm widths and precise edge structures promise to meet the demands of speed, energy efficiency, density, and functionality required for next-generation electronics. In this talk, we will discuss our approach to synthesize nanoribbons with tunable sub-5-nm widths, nearly atomically defined armchair edges, atomic thickness, unidirectional alignment, and controlled placement on conventional Ge and Ge-on-Si substrates via chemical vapor deposition (CVD). This technique is based on our discovery of a new regime of highly anisotropic crystal growth kinetics that enables the synthesis of high-aspect ratio nanoribbons. The precise control over the nanoribbon structure afforded by this synthesis technique transforms graphene from a zero-bandgap semimetal into a semiconductor with a technologically useful bandgap > 0.5 eV. The nanoribbons exhibit high performance in field-effect transistors in terms of their on-state conductance (~10³ μS μm^-1) and on/off current ratio (~10⁴). This wafer-scale, industry-compatible deposition technique overcomes major challenges in the production of nanoribbons, promising future nanoribbon-based semiconductor technologies.