At that scale, is it even useful to still call it “graphene”? 3nm is only 21 carbon atom diameters. How much of its desirable properties come from bulk effects? (Genuinely curious, I’m not qualified in chemistry).
Narrow and long strips of graphene are called nanoribbons in the literature. When they start to get really narrow their properties change significantly [1].
It’s probably workable in terms of material properties if you can manufacture it in the geometry needed, but I’m not an expert in 2d materials.
The edge of a graphene sheet is a defect that affects the electronic properties, with strong orientation dependence
However, in this article they intentionally introduce additional defects to tune the electronic properties, so there’s probably no fundamental issue. I agree with another poster here that manufacturing at scale in integrated devices is not obviously viable. Especially because it seems like a different method of introducing defects is needed if you want to grow the graphene by chemical vapor deposition.
[1] https://www.nature.com/articles/ncomms10177
Edit: spelling