One-dimensional confinement and width-dependent bandgap formation in epitaxial graphene nanoribbons
Hrag Karakachian, T. T. Nhung Nguyen, Johannes Aprojanz, Alexei Zakharov, Rositsa Yakimova, Philipp Rosenzweig, Craig Polley, T. Balasubramanian, Christoph Tegenkamp, Stephen R. Power, Ulrich Starke
Abstract
The ability to define an off state in logic electronics is the key ingredient that is impossible to fulfill using a conventional pristine graphene layer, due to the absence of an electronic bandgap. For years, this property has been the missing element for incorporating graphene into next-generation field effect transistors. In this work, we grow high-quality armchair graphene nanoribbons on the sidewalls of 6H-SiC mesa structures. Angle-resolved photoelectron spectroscopy (ARPES) and scanning tunneling spectroscopy measurements reveal the development of a width-dependent semiconducting gap driven by quantum confinement effects. Furthermore, ARPES demonstrates an ideal one-dimensional electronic behavior that is realized in a graphene-based environment, consisting of well-resolved subbands, dispersing and non-dispersing along and across the ribbons respectively. Our experimental findings, coupled with theoretical tight-binding calculations, set the grounds for a deeper exploration of quantum confinement phenomena and may open intriguing avenues for new low-power electronics.