Guilin Sun
Ansys Employee

It should be ok to simulate such sized device. Other customers simulate even larger.

You can first get the absorption density using an analysis group, such as from this example:

https://optics.ansys.com/hc/en-us/articles/360042454814-Avalanche-photodetector

and this one

https://optics.ansys.com/hc/en-us/articles/360042828913-Germanium-on-Silicon-lateral-photodetector

 

After obtaining the absorption power density in .mat data file, you can import to CHARGE.