(Invited) Highly Functional Graphene Nano-Electromechanical (GNEM) Devices for Advanced Switch and Sensor Applications

Abstract

Novel graphene nano-electro-mechanical (GNEM) devices are developed for low-voltage switching and ultra-sensitive chemical gas sensing applications. Doubly-clamped and cantilever GNEM switches with a local top actuation electrode are developed, and a pull-in voltage less than 5 V is realized. A naturally formed chromium oxide, introduced at the graphene-electrode contact interface, prevents the formation of C-Au chemical bonds, and the reversible switching operation was achieved. The 15-nm patterning of suspended graphene by helium ion beam milling is demonstrated. The reduction of the graphene nanoribbon width leads to the enhancement of temporal resistance change with the molecules adsorption on the graphene channel, which is beneficial for high-resolution sensing. We furthermore develop a GNEM chemical gas sensor device by using a bilayer graphene (BLG) beam suspended above a local bottom gold electrode, which features a slanted BLG channel with built-in tensile strain. By applying a substrate bias voltage of ± 15 V the adsorption processes of dilute CO2 gas molecules is accelerated, and we observe ‘quantized’ increments in the temporal resistance for the slanted BLG channel, which signifies single CO2 molecule adsorption / desorption events onto the BLG channel surface.