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Thin film Transistor
Posted Nov 30, 2011, 5:36 a.m. EST 3 Replies
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Hi,
I am currently working on my diploma-thesis and use Comsol 4.2a for simulating a thin film transistor. I calculate the current at the drain and source with an integral of the total flux of charge carrierers through the boundry. My problem is that the currents at drain and source are different, and that cannot be physically correct. I tried add weak constraints and differents model couplings, but either i get an error or it does not change the problem.
So my question is: How can I say Comsol that the currents (Integrals over boundaries) should be equal?
Thank you very much for the help that is hopefully coming
Elmar
ps. I have attached the file if someone want to look at it.
I am currently working on my diploma-thesis and use Comsol 4.2a for simulating a thin film transistor. I calculate the current at the drain and source with an integral of the total flux of charge carrierers through the boundry. My problem is that the currents at drain and source are different, and that cannot be physically correct. I tried add weak constraints and differents model couplings, but either i get an error or it does not change the problem.
So my question is: How can I say Comsol that the currents (Integrals over boundaries) should be equal?
Thank you very much for the help that is hopefully coming
Elmar
ps. I have attached the file if someone want to look at it.
Attachments:
3 Replies Last Post Dec 2, 2011, 9:00 a.m. EST
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Posted:
1 decade ago
Hi
have you checked that your model is mesh independent ? and that the mesh is already fine enough to extract any flux.
Then do not forget to read the KB and the doc on flux calculations and on ways to improve the integration via weak constraints (when possible)
Sorry I'm not by my WS so I cannot open your model today
--
Good luck
Ivar
have you checked that your model is mesh independent ? and that the mesh is already fine enough to extract any flux.
Then do not forget to read the KB and the doc on flux calculations and on ways to improve the integration via weak constraints (when possible)
Sorry I'm not by my WS so I cannot open your model today
--
Good luck
Ivar
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Posted:
1 decade ago
Hi,
thank you for your answer. I'll try fining the mesh at the boundaries and read the notes for flux calculations and weak constraints. (Probably I cant get to work with Comsol today.)
Elmar
thank you for your answer. I'll try fining the mesh at the boundaries and read the notes for flux calculations and weak constraints. (Probably I cant get to work with Comsol today.)
Elmar
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Posted:
1 decade ago
Hi again,
refining the mesh did not helped with the problem.
I also have tried different things. Add weak constraints in the boundary conditions and then plot c_lm, but its still different on source and drain (if plotted, if calculated it is the same, very confusing....) Tried reacf(c). Still different currents.
Added a weak constraint between the boundaries, which led to strong fluctuating currents (same at source and drain) with increasing voltage until comsol wasnt able to compute any further.
I think I need Ideal boundary constraints (called so in 3.5a, did not find anything in 42a so far). Is there a Modeling Guide for 42.a? Only have that one for 3.5a.
Thanks alot for any help.
Elmar
ps. Now the mesh is quite fine and it will compute for quite a while
refining the mesh did not helped with the problem.
I also have tried different things. Add weak constraints in the boundary conditions and then plot c_lm, but its still different on source and drain (if plotted, if calculated it is the same, very confusing....) Tried reacf(c). Still different currents.
Added a weak constraint between the boundaries, which led to strong fluctuating currents (same at source and drain) with increasing voltage until comsol wasnt able to compute any further.
I think I need Ideal boundary constraints (called so in 3.5a, did not find anything in 42a so far). Is there a Modeling Guide for 42.a? Only have that one for 3.5a.
Thanks alot for any help.
Elmar
ps. Now the mesh is quite fine and it will compute for quite a while
Attachments: