I am trying to deposit graphene from a custom-designed CVD setup using camphor as carbon precursor but as of now proper nm thin layer has nt yet been there on the copper substrate and the film has small holes over entire coverage.
Thank you Dr. Qijin Chi for your valuable suggesstion. Definitely i will try it out.
Try elevating the substrate temperature at deposition.
Look up the research topics at MIT Boston. There are folks working on the identical combination of materials at MIT.
I would suspect issues with surface preparation - roughness or contamination inhibiting locally the CVD process.
Thank you Adam Sir, even I think the same so I will improve my substrate pre-treatment.
A hole is an absence of matter that was existing before, copper seems to be randomly escaping at few points. There is an interesting phenomena happening, I was suspecting localized heating zone variations in copper. I may not be right.
Check out localizations of strain due to adiabatic heating.
The copper foil I am using is from Sigma Aldrich and yes I annealed the substrate but in hydrogen atmosphere.
what is the area of the foil that you are keeping on the quartz boat? even I have seen holes in cu foil specially when the copper foils are kept in a curved way on the boat . Interestingly when the cu foils are small in size then the holes were missing. it might be due to the strain effect.
Anwesha Mukherjee, yes that can be a reason. The size of Cu foil was around 2*1cms. Thank you for ur answer.
Dear Shah,
In the case APCVD, we it is very difficult to remove the imputities. Even though If we use UHP gases also we can't remove impurities. When we are loading into the quartz tube, how the substrate curvature , ar what temparature annealing has been done.
There are several cases that you can see the holes as follows;
When the copper foil was annealing around 900~1000℃, some gases which copper originally contains oxygen, or other sulfer may come out to the surface. So it become the surface impurites. Also even when you pre-annealed cu foil in inert or hydrogen atmospher, the hole cannot be fully removed. The holes are caused by lots of experiment factors, such as Cu purity, pre-annealing condition, surface roughness, and CVD chamber cleaness, etc. One more, If you transfer the graphene to other substrate such as si wafer, you can get easily extra holes because of non-perfect transfer. Thus, you'd better observe the surface of Cu foil right after graphene synthesis process. Honestly, I am also looking for the solution to perfectly remove the holes.^^
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