Controlled removal of monolayers for bilayer graphene preparation and visualization

Abstract

Bilayer graphene, unlike monolayer graphene, provides a tunable electronic energy gap when an electrical field is applied across the layers, and therefore holds great potential in the semiconductor industry. Here, we demonstrate a facile technique to obtain bilayer graphene structures on the growth substrate by controlling oxidation to remove monolayers, while retaining the bilayer electronic properties. We found that this precise oxidation process selectively destructs monolayers while preserves the qualities of bilayers, evidenced by the expected quantum Hall effect and exceptional room temperature carrier mobilities of ∼3500 cm² V⁻¹ s⁻¹ obtained from an electrical transport measurement. In addition, visualization of the bilayers, which serve as nuclei for graphene growth, opens the door to understanding the actual mechanism of the graphene growth process which eventually can lead to the optimized synthesis.