Stacking of nanocrystalline graphene for Nano-Electro-Mechanical (NEM) actuator applications

TL;DR

This paper demonstrates a novel stacking method for nanocrystalline graphene (NCG) to create low-voltage NEM switches with potential for advanced logic applications, addressing fabrication challenges.

Contribution

It introduces a stacking approach with a buried NCG layer and dielectric separation, enabling low-voltage actuation and improved fabrication of NEM switches.

Findings

Observed contact at below 1.5 V voltage

No pull-out due to thin sacrificial layer

Potential for NEM contact switches and logic devices

Abstract

Graphene nano-electro-mechanical switches are promising components due to their excellent switching performance such as low pull-in voltage and low contact resistance. Mass fabrication with an appropriate counter electrode remains challenging. In this work, we report the stacking of nanocrystalline graphene (NCG) with a 70-nm dielectric separation layer. The buried NCG layer is contacted through the formation of vias and acts as actuation electrode. After metallization, the top 7.5-nm thin NCG layer is patterned to form double-clamped beams, and the structure is released by hydrofluoric acid etching. By applying a voltage between the top and buried NCG layer, a step-like current increase is observed below 1.5 V, caused by the contact of the movable beam with the buried NCG. No pull-out is observed due to the thin sacrificial layer and high beam length, resulting in low mechanical restoring force. We discuss the possible applications of the NCG stacking approach to realize Nano-Electro-Mechanical (NEM) contact switches and advanced logical components such as a AND logic.