Menu

Discussion Forum

New Discussion
Filtrer

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

COMSOLPIN photodiode example simulation (updated)

Posted 8 mars 2016, 19:31 UTC−5 Low-Frequency Electromagnetics, Semiconductor Devices, Wave Optics, Studies & Solvers Version 5.0 3 Replies

Yuchu He
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi, i'm trying to do a photodiode simulation based on the gaas PIN diode example from comsol. In this example, the electromagnetic wave is excited from port1 and port 2 at the semiconductor boundary, with uniform electric field. I made a slight change to the example. Instead of exciting a uniform wave at port 1, now i'm exciting it with a Gaussian field distribution, i.e, Ez=exp(-(x/1000[nm])^2). I've also made some change to the meshing(which works fine if the excitation is uniform). However, i'm getting this error:
Attempt to evaluate negative power of zero.
- Function: ^
Failed to evaluate temporary symbolic derivative variable.
- Variable: comp1.ewfd.normE@VDN${realdot@2}
- Defined as: (0.5*((realdot(comp1.ewfd.Ez,comp1.ewfd.Ez)+(realdot(comp1.ewfd.Ex,comp1.ewfd.Ex)+realdot(comp1.ewfd.Ey,comp1.ewfd.Ey)))^(-0.5)))
Failed to evaluate temporary symbolic derivative variable.
- Variable: comp1.semi.Enorm0_wo@VDN${realdot@2}
- Defined as: ((0.5*((realdot(comp1.ewfd.Ez,comp1.ewfd.Ez)+(realdot(comp1.ewfd.Ex,comp1.ewfd.Ex)+realdot(comp1.ewfd.Ey,comp1.ewfd.Ey)))^(-0.5))))
Failed to evaluate expression.
- Expression: d(((comp1.semi.Enorm0_wo*unit_m_cf)/unit_V_cf),{realdot@2})

anyone has any idea what might be the cause? Thanks a lot!
3 Replies Last Post 22 févr. 2017, 01:49 UTC−5
Yuchu He
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 8 years ago 9 mars 2016, 09:16 UTC−5
is the negative power of zero due to meshing, convergence, or some other reason?
is the negative power of zero due to meshing, convergence, or some other reason?
Yuchu He
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 8 years ago 10 mars 2016, 12:41 UTC−5
any help would be appreciated, otherwise i probably will switch to TCAD altas to do this, which requires learning the new software...
any help would be appreciated, otherwise i probably will switch to TCAD altas to do this, which requires learning the new software...
Ankit Kumar Pandey
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 7 years ago 22 févr. 2017, 01:49 UTC−5

Hi, i'm trying to do a photodiode simulation based on the gaas PIN diode example from comsol. In this example, the electromagnetic wave is excited from port1 and port 2 at the semiconductor boundary, with uniform electric field. I made a slight change to the example. Instead of exciting a uniform wave at port 1, now i'm exciting it with a Gaussian field distribution, i.e, Ez=exp(-(x/1000[nm])^2). I've also made some change to the meshing(which works fine if the excitation is uniform). However, i'm getting this error:
Attempt to evaluate negative power of zero.
- Function: ^
Failed to evaluate temporary symbolic derivative variable.
- Variable: comp1.ewfd.normE@VDN${realdot@2}
- Defined as: (0.5*((realdot(comp1.ewfd.Ez,comp1.ewfd.Ez)+(realdot(comp1.ewfd.Ex,comp1.ewfd.Ex)+realdot(comp1.ewfd.Ey,comp1.ewfd.Ey)))^(-0.5)))
Failed to evaluate temporary symbolic derivative variable.
- Variable: comp1.semi.Enorm0_wo@VDN${realdot@2}
- Defined as: ((0.5*((realdot(comp1.ewfd.Ez,comp1.ewfd.Ez)+(realdot(comp1.ewfd.Ex,comp1.ewfd.Ex)+realdot(comp1.ewfd.Ey,comp1.ewfd.Ey)))^(-0.5))))
Failed to evaluate expression.
- Expression: d(((comp1.semi.Enorm0_wo*unit_m_cf)/unit_V_cf),{realdot@2})

anyone has any idea what might be the cause? Thanks a lot!


Please check initial values under Electromagnetic Waves, Frequency Domain study. I faced same problem due to zero (0) value under Electric field for x,y and z. This problem was solved using Ez=1
[QUOTE] Hi, i'm trying to do a photodiode simulation based on the gaas PIN diode example from comsol. In this example, the electromagnetic wave is excited from port1 and port 2 at the semiconductor boundary, with uniform electric field. I made a slight change to the example. Instead of exciting a uniform wave at port 1, now i'm exciting it with a Gaussian field distribution, i.e, Ez=exp(-(x/1000[nm])^2). I've also made some change to the meshing(which works fine if the excitation is uniform). However, i'm getting this error: Attempt to evaluate negative power of zero. - Function: ^ Failed to evaluate temporary symbolic derivative variable. - Variable: comp1.ewfd.normE@VDN${realdot@2} - Defined as: (0.5*((realdot(comp1.ewfd.Ez,comp1.ewfd.Ez)+(realdot(comp1.ewfd.Ex,comp1.ewfd.Ex)+realdot(comp1.ewfd.Ey,comp1.ewfd.Ey)))^(-0.5))) Failed to evaluate temporary symbolic derivative variable. - Variable: comp1.semi.Enorm0_wo@VDN${realdot@2} - Defined as: ((0.5*((realdot(comp1.ewfd.Ez,comp1.ewfd.Ez)+(realdot(comp1.ewfd.Ex,comp1.ewfd.Ex)+realdot(comp1.ewfd.Ey,comp1.ewfd.Ey)))^(-0.5)))) Failed to evaluate expression. - Expression: d(((comp1.semi.Enorm0_wo*unit_m_cf)/unit_V_cf),{realdot@2}) anyone has any idea what might be the cause? Thanks a lot! [/QUOTE] Please check initial values under Electromagnetic Waves, Frequency Domain study. I faced same problem due to zero (0) value under Electric field for x,y and z. This problem was solved using Ez=1

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content