Patterning of highly oriented pyrolytic graphite ͑HOPG͒ was demonstrated by oxygen plasma etching of lithographically patterned substrates. Periodic arrays of islands, or holes of several microns on an edge, were obtained on freshly cleaved HOPG surfaces which had been prepared with SiO 2 mask stops and then oxygen plasma etched. The etching process is described, including a study of etch rate as a function of rf power, and morphology was characterized with scanning electron microscopy.The graphite basal plane, also known as graphene, is a hexagonal network of sp 2 covalently bonded carbon atoms. 1 Graphite is very chemically stable in nonoxidizing environments, and is mechanically very stiff ͑the C 11 compliance constant is 1060 GPa͒, and these properties lead to its use in a variety of applications including in high-temperature, highstrength composites. 1 It is well established that the graphite basal plane is inert to chemical reaction with molecular oxygen, while it has limited resistance to atomic oxygen; at only 323 K, attack by atomic oxygen of graphite takes place readily. 2 Highly oriented pyrolytic graphite ͑HOPG͒ is a manmade material which is polycrystalline with highly oriented graphene sheets; the typical domain size in HOPG is 1-10 m in the basal plane and Ͼ0.1 m perpendicular to the basal plane. 3 We were motivated to pattern HOPG because of our interest in the mechanical strength of graphite in the basal plane, which has not been determined to date. Mechanical strengths as high as ϳ300 GPa for defect-free regions are theoretically predicted from local-density approximation calculations on a truncated graphene sheet, 4 and one might also expect from theoretical calculations on carbon nanotubes ͑which are graphene sheets wrapped into cylinders͒ that the graphene sheet strength will be remarkably high; 5 for comparison, the tensile strength of a high-grade tool steel oil quenched from 1143 K and single tempered at 478 K is 2.345 GPa. 6 One approach we have been recently developing for studying the mechanical properties of graphene is to pattern HOPG and then to manipulate the islands which are formed to obtain very thin sheets. We have reported on these studies separately. 7 Here, we report the creation of patterned islands and holes in HOPG, concentrating particularly on the lithographic patterning of appropriate mask stops and the oxygenplasma-etching method used.Beyond our interest in manipulating thin, lithographically prepared graphite islands, there are several other reasons to want to pattern HOPG. First, surface patterning may find application in developing ''graphene origami,'' a technique which may result in novel nanodevices by fabricating carbon by design. 7,8 Second, patterned HOPG surfaces can be used as special substrates for experiments in chemistry, biology, and medical research. Unique micrometer-or nanometer-sized containers can be created by etching small holes into HOPG substrates. As an example, Patrick, Cee, and Beebe studied the behavior of molecules on HOPG surface havin...
