Learning Forum

[HAOYU LIU]

This is my structure, a photodiode, carriers are generated in p layer (red region), eight rectangle holes are air, p region is from 0.3 um to 0.9 um (z axis), holes are from (0.3 um to 0.8 um). When I add carrier distribution monitor in the hole region and across hole region, when it observes the carrier in hole region? The material is air, it's strange

[Guilin Sun]

Somehow the reply from last week did not submit successfully.

The is  maily due to the meshing. please refer to this article: https://www.mechead.com/mesh-methods-and-element-types-in-ansys-workbench/

The small holes may not be well meshed to have the surved surfaces so the finite elements show something inside the hole.

When a hole is very small, it needs many small elements to preserve its geometry shape, which in turn requires significant number iteration, as the meshing begins from coarse edge length. You can try to add local constraint mesh.

 

[HAOYU LIU]

 

The hole width is 0.1 um for each and when I add mesh constraint of 0.005 um at the position of holes, it still has such strange performance. But if I extand the thickness of holes from 0.5 um (0.3 to 0.8) to 0.6 um (0.3 to 0.9, the hole p layer), it will not has such strange performance, why?

 

[Guilin Sun]

This is most likely due to the fact that the 0.1um is a long and thin layer for meshing. Your test clearly shows it. Meshing such thin layer efficiently is a challenge in many cases.