Selective etching of multilayer graphene with ultra-low impact energy oxygen ions

Abstract

The practical application of graphene in various electronic and optoelectronic devices requires precise control of its spatial confinement. Ion beam-based techniques are a promising candidate in the top-down route of graphene patterning. However, conventional ion beam techniques can be used to precisely etch graphene laterally but are too coarse to enable selective etching of the desired number of graphene in its multilayer form. In this work, the application of ultra-low impact energy and high incident angle oxygen ions in addition to control over lateral dimensions of multilayer graphene enables selective etching of a specified number of layers. In situ annealing performed without removing a sample from a vacuum ensures that the defects occurring in the underlying layers are healed. The proposed method is reproducible and fast, as it can etch a single layer of graphene from 0.5 x 0.5 mm2 area in one hour for the beam with a diameter of about 5μm. The protocol, therefore, enables the realization of complex graphene patterns with not only precisely controlled dimensions but the number of remaining layers as well.