Improved Graphene Blisters by Ultrahigh Pressure Sealing

Graphene is a very attractive material for nanomechanical devices and membrane applications. Graphene blisters based on silicon oxide microcavities are a simple but relevant example of nanoactuators. A drawback of this experimental setup is that gas leakage through the graphene-SiO₂ interface contributes significantly to the total leak rate. Here, we study the diffusion of air from pressurized graphene drumheads on SiO₂ microcavities and propose a straightforward method to improve the already strong adhesion between graphene and the underlying SiO₂ substrate, resulting in reduced leak rates. This is carried out by applying controlled and localized ultrahigh pressure (>10 GPa) with an atomic force microscopy diamond tip. With this procedure, we are able to significantly approach the graphene layer to the SiO₂ surface around the drumheads, thus enhancing the interaction between them, allowing us to better seal the graphene-SiO₂ interface, which is reflected in up to ∼ 4 times lower leakage rates. Our work opens an easy way to improve the performance of graphene as a gas membrane on a technological relevant substrate such as SiO₂.