Edge states and ballistic transport in zigzag graphene ribbons: The role of SiC polytypes

Le résumé fourni par la source

Zigzag-edge graphene sidewall ribbons grown on $6H$-SiC ${11\overline{2}n}$ facet walls are ballistic conductors. It is assumed that graphene sidewall ribbons grown on $4H$-SiC ${11\overline{2}n}$ facets would also be ballistic. In this work, we show that SiC polytype indeed matters: ballistic sidewall graphene ribbons only grow on $6H$-SiC facets. $4H$ and $4H$-passivated sidewall graphene ribbons are diffusive conductors. Detailed photoemission and microscopy studies show that $6H$-SiC sidewall zigzag ribbons are metallic with a pair of $n$-doped edge states associated with asymmetric edge terminations. In contrast, $4H$-SiC zigzag ribbons are strongly bonded to the SiC, severely distorting the ribbon's $\ensuremath{\pi}$ bands. ${\text{H}}_{2}$ passivation of the $4H$ ribbons returns them to a metallic state but they show no evidence of edge states in their photoemission-derived band structure.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.