Suspended graphene electromechanical switches for energy efficient electronics

Improving the energy efficiency of electronics is one of the grand challenges of semiconductor device physics, as global energy consumption by electronics grows in tandem with society’s growing reliance on information technology. Computationally intensive applications such as artificial intelligence further incentivizes the improvement of energy efficiency of electronics. At the corpuscular level of the transistor, the challenge is to reduce the operating voltage of the electronic switch while maintaining a sufficient on/off current ratio for reliable circuit operation. Monolayer graphene is a light material with low elastic modulus for flexure and low adhesion energy, ideal for the development of electromechanical switches with low-voltage operation. Critically, monolayer graphene has an elastic modulus lower than that of any other membrane due to its atomic thinness, which in turn enables deflection with less force than any other membrane. In this article, we review recent progress in the development of low-voltage graphene electromechanical switches. We present a general overview of the motivation for low-voltage switches, thermodynamic limits, and the scaling of on/off current ratio with voltage. A summary of the theory of suspended graphene monolayer switches follows. Simple theoretical models for the scaling of pull-in voltage, actuation energy and adhesion energy with device dimensions are reviewed. Experimental work over the past decade towards the realization of suspended graphene switches in both two-terminal and three-terminal configurations is summarized. Our review concludes with an outlook on the continued development of low-voltage graphene switches.