Atomic-Scale Movement Induced in Nano-Ridges by Scanning Tunneling Microscopy on Epitaxial Graphene Grown on 4H-SiC(0001)

TL;DR

This study uses atomic-resolution STM to observe nanoscale ridges on epitaxial graphene and investigates how scanning induces atomic-scale movements, revealing effects of electrostatic attraction and substrate bonding.

Contribution

It demonstrates atomic-scale movement in nano-ridges of epitaxial graphene caused by STM scanning, highlighting the influence of electrostatic and substrate interactions.

Findings

Nano-ridges are 0.1 nm high and 25-50 nm wide.

Apparent 100% lattice constant enlargement observed.

Horizontal movement attributed to electrostatic attraction and weak substrate bonding.

Abstract

Nanoscale ridges in epitaxial multilayer graphene grown on the silicon face of 4 degree off-cut 4H-SiC (0001) were found using scanning tunneling microscopy (STM). These nano-ridges are only 0.1 nm high and 25-50 nm wide, making them much smaller than previously reported ridges. Atomic-resolution STM was performed near and on top of the nano-ridges using a dual scanning technique in which forward and reverse images are simultaneously recorded. An apparent 100% enlarged graphene lattice constant is observed along the leading edge of the image for both directions. Horizontal movement of the graphene, due to both an electrostatic attraction to the STM tip and weak bonding to the substrate, is thought to contribute to the results.