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For graphene, precise patterning without an individual manipulation is an almost solved problem. There was a research paper earlier this year where a new metho

For graphene, precise patterning without an individual manipulation is an almost solved problem. There was a research paper earlier this year where a new method of producing graphene has been demonstrated, which does not have any of the disadvantages of the previous methods. The new method is by converting a superficial layer of a standard silicon carbide monocrystalline wafer into graphene, by removing the silicon atoms. This allows the production and patterning of high-quality graphene by the methods of the integrated circuit industry. Only the placement and attachment of porphyrin molecules is a problem for which a solution would need to be found. It might be possible to find a coating non-reactive with porphyrin, in which to etch holes by standard photolithographic means, exposing the graphene electrodes to which the porphyrin must attach, then an immersion in a porphyrin solution might cause the molecules to attach in the desired places. While such a technology is many years away, it does not seem impossible and (having worked in semiconductor IC manufacturing) I do not believe that it would need over 10 years of development, though it is unlikely to happen in less than 5 years. The main factor that would determine whether such a technology would become viable is whether it would demonstrate a better potential for future evolution than the other alternatives that are explored currently for the certain replacement of the silicon in the highest-performance integrated circuits, during the next decade. If it will be shown to be promising enough, then enough resources will be provided to solve the technological difficulties.

klyrs 3y ago
> The new method is by converting a superficial layer of a standard silicon carbide monocrystalline wafer into graphene, by removing the silicon atoms. This is cool! My understanding of chip fab rather weak, but it sounds like this only gets you transistors on a single substrate-adjacent layer. Is that not a significant limitation?
- adrian_b 3y ago
  This is not a limitation, because it is the same for almost all other methods of making integrated circuits, where the transistors are also made inside a very thin superficial layer. Only now, for the next generations of CMOS manufacturing processes, there are some experimental technologies to make pairs of transistors that are stacked one over the other, to double the areal density of transistors. For now, the most significant problem for becoming able to make integrated circuits on graphene is to find methods to make better electrical contacts between the metal layers required for interconnections and the graphene transistors. The methods currently known introduce series resistances that are large, negating the intrinsic speed advantage of the graphene.

klyrs 3y ago

> The new method is by converting a superficial layer of a standard silicon carbide monocrystalline wafer into graphene, by removing the silicon atoms. This is cool! My understanding of chip fab rather weak, but it sounds like this only gets you transistors on a single substrate-adjacent layer. Is that not a significant limitation?

adrian_b 3y ago
This is not a limitation, because it is the same for almost all other methods of making integrated circuits, where the transistors are also made inside a very thin superficial layer. Only now, for the next generations of CMOS manufacturing processes, there are some experimental technologies to make pairs of transistors that are stacked one over the other, to double the areal density of transistors. For now, the most significant problem for becoming able to make integrated circuits on graphene is to find methods to make better electrical contacts between the metal layers required for interconnections and the graphene transistors. The methods currently known introduce series resistances that are large, negating the intrinsic speed advantage of the graphene.