Learning Forum

[mhu]

Hello,

I am designing a photodiode. I followed the vertical photodiode example provided by lumrical. While the simulation is fine for 2D charge simulation but the 3D simulation is not running and showing the following error. After clicking the online referene it took me to the CHARGE settings and asked to change something here. Can you please tell me why 3D simulaton is not running?

 

[Khashayar Ghaffari]

Hi,

Running the 3D simulation can indeed be more challening in terms of convergence behavior given the added complexity of the problem. Here I suggest the following as you try to troubleshoot:

1 - Try reducing the simulation region area. For example try running the simulation for a smaller 3D portion. This might reduce the simulation complexity and allow you to obtain some initial results.

2 - Please make sure the first voltage step is 0 V; even if you are interested in the results at another bias, sweeping from 0V will help with convergence behavior as the solution at each bias relies on the previous step. Also, make sure the voltage steps are reasonably small given the problem at hand (e.g. 0.25 V or 0.5V).

3 - When sweeping the voltage do you obtain some partial results (for earlier bias points)? If so you can look into the available results, especially those at the last available bias point. This could give you insights in case there is a rapid increase in current or extreme electric field observed in a region.

4 - Try working with the convergence settings available in the advanced tab. For example increasing the iteration number and changing the solver type could be helpful.

Best regards

[mhu]

 

Hi,

Thank you for your valuable advice. After some changing in advanced tab I got some partial result which is followed the trend of 2D simulation but the simulation stopped at 76%. I am not sweeping over a range of voltage because it takes huge amount of time only simulating at target bias voltage to see how it follows 2D result. Maybe this is creating problem?

*previously I have designed another photodetector following the example of vertical photodetector given by lumerical and also simulated vertical detector in 3D. That time 3D simulation ran smoothly but I had to put a material in background material settings in the simulation region tab otherwise, the simulation didnt ran. But 2D and 3D result didnt match both the times. 3D current was almost 10 times smaller. Do you have any idea why this happened?

Best regards