A group of researchers representing several institutions report in Science they have gained new abilities to “print” graphene oxide-based nano-scale replacements for IC wiring and some semiconductor devices using a method that employs an atomic force microscope to act as a printer head do the detailed work of tuning the conductivity of the material in precise patterns.
GO is an interesting material because it is more resilient to mechanical stresses than standard graphene. Furthermore, in a reduced form, GO becomes a semiconductor (reduced GO – rGO – has a conductivity that is 33,000 times higher than that of doped hydrogenated amorphous silicon).
The innovation the researchers are pioneering is the use of a heated AFM tip on GO to precisely create nanoribbons of rGO. The group – from Georgia Tech, Naval Research Lab, Chung Ang University (Korea), University of Illinois at Urbana-Champaign and CNRS-Institut Néel (France) – didn’t invent thermochemical nanolithography, but the were the first to employ TCNL, via an AFM probe tip, to reduce patterned regions of GO simply by varying the temperature of the tip.
They tested their TCNL method on both GO flakes on a SiOx/Si substrate and large-area GO films (>15 mm2) formed from epitaxial graphene grown on the carbon face of silicon carbide. They were able to print the rGO nanoribbons at a rate of about 2 µm per second, forming ribbons as narrow as 25 nm. They were able to demonstrate the formation of nanoribbons in zigzag and cross-shaped patterns.
What’s down the road for this? The researchers envision graphene nanoelectronics made by using large arrays of independent heated probe tips that would “print” nanostructures on wafer-scale areas at high speed.