how define_optical and electrical simulation region_for_comb shape_pin Si solar cell



I am trying to simulate a comb shape pin Si solar cell using Lumerical. Can you please help me in defining optical and electrical stimulation regions to have accurate results, please?
thanks a lot in advance


Dear @heejae86

Thank you for reaching out. Can you please clarify what you mean by “defining optical and electrical simulation region”? Have you setup your simulation file?



I mean optical simulation region in FDTD and elctrical simulation region in DEVICE, based on planar Si solar cell tutorial video, first an optical unit cell is defined and then repeation period. Also for electrical simulation an electrical unit cell is defined and then period to repeat the unit cell. My problem is that I dont know how to define unit cells in my structure.


Hi @heejae86, in your solar cell, where is the optical illumination coming from? Is it normal to the 2D cross-section you have shown here?



this is the top view of my solar cell. and the sunlight is normal to this top view.


Thanks for the confirmation. Here are my suggestions about the unit cells. Please let me know if you have any questions.

In the 2D unit cell case, you can use the period in the “generation rate” analysis group to make sure that the generation rate data will cover the entire structure during electrical simulation in DEVICE.


In the shown optical unit cell (3D white box). The metal also is inside of the unit cell. the width of this metal is about W4 = 0.5um. then is it fine to be inside of the optical unit cell?

The thickness of the cell is normal to the monitor plane. Also as I mentioned teh sunlight is also normal to the monitor lane.

W1, W2 and w3 are respectively the width of N+, P+ and intrinsic region.


Thanks a lot dear Alaam. I am sorry I think I didnt express my mean well. So sorry.
The shape is the top view of solar cell and the sunlight shines to this top part of solar cell. (I mean the sun light is normal to the monitor, when we look at this figure)


Hi @heejae86, no worries. Can you give me an idea about the values of w1, w2, and w3?


Thanks a lot for your replies and helps.
W1 =W2 = 4um, W3 = 36um.


Thanks for the info. It looks like that the unit cells I have mentioned previously should work for your optical (and electrical) simulations (even with the updated doping profile). Given that W3 is much larger compared to the metal regions, you may even want to perform a 2D simulation on silicon only to keep things simple.


Dear aalam thanks a lot for your help.