Abstract
High quality graphene nanoribbons epitaxially grown on the sidewalls of silicon carbide (SiC) mesa structures stand as key building blocks for graphene-based nanoelectronics. Such ribbons display 1D single-channel ballistic transport at room temperature with exceptionally long mean free paths. Here, using spatially-resolved two-point probe (2PP) measurements, we selectively access and directly image a range of individual transport modes in sidewall ribbons. The signature of the independently contacted channels is a sequence of quantised conductance plateaus for different probe positions. These result from an interplay between edge magnetism and asymmetric terminations at opposite ribbon edges due to the underlying SiC structure morphology. Our findings demonstrate a precise control of transport through multiple, independent, ballistic tracks in graphene-based devices, opening intriguing pathways for quantum information device concepts.
Highlights
High quality graphene nanoribbons epitaxially grown on the sidewalls of silicon carbide (SiC) mesa structures stand as key building blocks for graphene-based nanoelectronics
Density functional theory (DFT) and transmission electron microscopy (TEM) have revealed that graphene growth is seeded at trenches close to the lower edge of the SiC facet structure, while the top of the ribbon merges into the buffer layer above the mesa[19,20,21,22]
For mesa structures running along the [1100]-direction and with trench depths of around 20 nm, SiC(11 2n) facets approximately 40 nm wide with an inclination of 25–30° are formed during annealing
Summary
High quality graphene nanoribbons epitaxially grown on the sidewalls of silicon carbide (SiC) mesa structures stand as key building blocks for graphene-based nanoelectronics. Such ribbons display 1D single-channel ballistic transport at room temperature with exceptionally long mean free paths. The signature of the independently contacted channels is a sequence of quantised conductance plateaus for different probe positions These result from an interplay between edge magnetism and asymmetric terminations at opposite ribbon edges due to the underlying SiC structure morphology. The explicit consideration of zigzag-edge magnetisation and transverse electric field effects within tight-binding calculations captures in detail the formation and localization of the experimentally-observed edge and bulk channels
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