A two-dimensional structure graphene STM tips fabricated by microwave plasma enhanced chemical vapor deposition

The atomic edge, excellent conductivity, stable chemical and mechanical properties make graphene a good candidate for the scanning tunneling microscopy (STM) tip. Here, a one-step growth method is used to fabricate graphene STM tips. The graphene was directly grown on a sharp tungsten tip vertically by using microwave plasma enhanced chemical vapor deposition method without any catalyst. The high resolution TEM image demonstrated that inert W2C layer was formed at the surface of tungsten during growth which can protect the oxidation of tungsten tip and promote the electric conductivity of graphene STM tip of 4000 times than the oxidative tungsten tip. The in situ TEM field evaporation experiments revealed that the graphene has a good stability under high electric field of 24.7 V/nm. Using the graphene STM tip, atomic resolution images of highly oriented pyrolytic graphite and tungsten disulfide were obtained. Our experiment results demonstrated the graphene STM tip was available to get atomic resolution image for at least one week. It is a promising approach to fabricate STM tips for high resolution imaging in a fast and economical way. (C) 2017 Elsevier Ltd. All rights reserved.