High-precision AFM cutting of graphene <i>via</i> improved electrode-free local anodic oxidation for electronic band engineering

Atomic force microscopy (AFM) cutting of graphene <i>via</i> electrode-free localized anodic oxidation (EFLAO), with great convenience and flexible pattern design, has been widely used in various experimental investigations of graphene and its nanostructures. However, the fabrication precision, <i>i.e.</i>, the width of an etched nanotrench, has been limited to 60-100 nm, hindering its potential for creating quantum confinement effects or engineering band structures. Here, we report a greatly improved EFLAO technique that achieves etching precision of nanotrenches as narrow as 15 nm, allowing for the reliable fabrication of graphene nanoribbon (GNR) arrays with a 50 nm period. We also demonstrated that these GNR arrays with such a small period can serve as a periodic gating electrode to engineer graphene band structures and produce artificial graphene superlattices. The improved EFLAO provides a convenient approach for fabricating high-precision graphene nanostructures using just an AFM setup, facilitating the exploration of quantum confinement effects and other quantum phenomena in graphene and other carbon materials.