Low-temperature compatible electrostatic comb-drive actuators with integrated graphene

We present the fabrication process and characterization of silicon-based electrostatic comb-drive actuators with integrated single-layer graphene. The micro-machined comb-drive actuators are designed such that they can induce significant mechanical forces to strain graphene (up to 1%) allowing to systematically investigating its mechanical and electromechanical properties. The amount of induced strain is controlled by an applied voltage between capacitively coupled “fingers” of the micromechanical actuator. By using highly doped silicon the integrated comb-drive devices can be actuated also at cryogenic temperatures, where a higher energy resolution will provide potentially more insights into the fundamental electromechanical properties of graphene. Further device functionality is introduced by a local bottom gate that enables to control the carrier concentration in graphene by tuning the Fermi level. Here, we show the fabrication and characterization of such comb-drive actuators as well as a precise transfer technique to integrate individual sheets of graphene. A postprocessing step of direct plasma etching was implemented to structure suspended graphene flakes allowing better mechanical functionality of the integrated device.