Graphene is an amazing material with an equally annoying set of constraints that make it extremely difficult to work with. One of the most significant problems we’ve had with adapting the material for commercial use is producing it. While a number of methods of graphene production have been demonstrated, none of them have lent themselves to the kind of massive scale that typifies the silicon industry’s ability to manufacture, well, silicon. In early 2016, the entire foundry industry was estimated to be capable of nearly 12 million wafer starts per month (in 200mm-equivalent wafers). Graphene doesn’t have to scale all the way up to that level before entering production, but any widespread adoption of the material requires it to achieve its own economy of scale. New research from Rice University and the Oak Ridge National Laboratory may have moved us closer to that idea, with a new method of creating a large continuous roll of graphene.
The researchers at ORNL used a chemical vapor deposition (CVD) process to manufacture graphene, which is something we’ve been doing for quite awhile already, but with a new twist. Here’s how Phys.org describes it:
Much like traditional CVD approaches to produce graphene, the researchers sprayed a gaseous mixture of hydrocarbon precursor molecules onto a metallic, polycrystalline foil. However, they carefully controlled the local deposition of the hydrocarbon molecules, bringing them directly to the edge of the emerging graphene film. As the substrate moved underneath, the carbon atoms continuously assembled as a single crystal of graphene up to a foot in length.
By running the process at a high temperature and carefully monitoring the gas mixture concentration, the team was able to keep the growth occurring where they wanted it to. Yielding a single crystal sheet structure, as opposed to clusters of the material, also creates a more uniform and larger continuous sheet of material.
A research team developed a novel method that produces large, monolayer single-crystal-like graphene films more than a foot long. Credit: Andy Sproles/Oak Ridge National Laboratory, US Dept. of Energy
Large single crystals are more mechanically robust, and may even have higher conductivity, ORNL lead coauthor Ivan Vlassiouk told Phys.Org. “[It’s] because weaknesses arising from interconnections between individual domains in polycrystalline graphene are eliminated,” he said.
As for what this could mean for semiconductor and other applications of graphene, it could represent a genuine breakthrough…given sufficient time. Right now, figuring out what graphene can even theoretically do has been so limited because we can’t make much of it. But finding one way to manufacture it doesn’t necessarily or automatically help. That’s because we don’t know if we can scale this manufacturing method up either. Plus, companies that might benefit from incorporating graphene in various ways haven’t had enough of it to explore what those might be.
In addition, if we can scale it and benefit from incorporating it, the benefits might still be smaller than the cost. And that’s before we get to the difficult question of including graphene in logic circuits, where we’d be flipping the entire question on its head. A huge amount of work over the past 50 years has gone into making semiconductors conduct when we want them to, and stop when we don’t. Graphene flips that equation on its head. Now we need to stop it from conducting when we don’t want it to (graphene literally needs no help conducting).
I hate to yank back the promising narrative so quickly, but that’s the nature of the business. Years of slow progress on fronts like this, all with a hopeful long-term eye towards commercialization.