# hole in a layer

#1

Dear all,
I have a thin layer of Si (2 nm) on a substrate. I want to put a Au disc in such a way that makes a hole in the Si layer (i.e., the Au disc will replace the Si). Problem: the mesh of the layer must by 1, but the Au disc must be 2, so if I put first the layer and then the disc, the mesh order would take preferentially the Si. Please, find attached the file with the simulation.

Thank you very much in advance.
Cheers,Au_disk Si layer.fsp (282.2 KB)

#2

Dear @pedrueza

If I understood your question correctly, you want the gold disk to override thin silicon layer. To do this, you can set the mesh order of thin layer_Si to 2 and Au-disk to 1. You can use an index monitor to make sure that you have set them properly:

[quote=“pedrueza, post:1, topic:5409”]
Problem: the mesh of the layer must by 1, but the Au disc must be 2,
[/quote]

I am a bit confused what you mean here? Why the mesh of Thin layer_Si needs to be 1?

Thanks

#3

Dear @bkhanaliloo,
It is true that I can override the mesh order from the material database, but a mesh of order 1 takes long time in the calculation (in fact, I want to put bigger discs).
I don’t know if the solution of putting the Si layer before in the objects tree will solve the problem, as suggested in the web.

I have another question, and is related with the position of the monitors, that by the way I don’t know if the ones of the file (I upload it again in this post) are the correct ones.Au_disk Si layer.fsp (281.3 KB)

If I consider only the layer, I get the following transmittance (“Trans” monitor), so if the monitor is inside gives the correct answer.

However, for the Au disc, it happens the opposite: if the monitor is outside, I get the correct spectra.

I know that you answer this in my previous post, but why is different the results for films and for a nanostructure, depending of the position of a transmittance monitor? again, is this the correct monitor to measure transmittance?
Thank you very much for your help.
Cheers,

#4

Dear @pedrueza

I think you are confusing mesh order with mesh accuracy (please correct me if I am wrong). Mesh order only effects which material to consider on the overlapped areas and has nothing to do with the size of the mesh. This can also be done by correctly putting material in the object tree, but the results of these two approaches are identical.

Regarding your second question: Since you are using TFSF, location of the monitor defines if you are going to measure the total field (inside TFSF source) or scattered filed (outside the box). Depending on what you want to measure (total transmission or scattered field), you can place monitor inside or outside the TFSF box. Please refer to this link:

https://kb.lumerical.com/en/index.html?ref_sim_obj_sources_tfsf.html