newby question

[wolfgang...@googlemail.com]

Hello,

I am new to devsim.
So far I have modified the 2Dcap-example to get some understanding (see attached).
In order to get more insight I would like to add some fixed charge-density so that I end up with
the poisson-equation rather than the laplace-equation.

As far as I understand I need to add some node-model or volume model to the bulk equation
to add the extra term to the integration.

Could anybody give me a hint?

Kind regards,

Wolfgang

[Juan E. Sanchez]

Hello Wolfgang,

You would need to specify a node model containing the charge term:

node_model(device="MyDevice", region="air",
name="charge",equation="1.6e-19*1")

and then add the node_model to the bulk equation for the region:

equation(device="MyDevice", region="air", name="PotentialEquation",
variable_name="Potential",edge_model="ElectricField",
node_model="charge", variable_update="default")

Please note that the charge is not included at the contact nodes,
because the contact equations swap out the bulk equations for their own.

The charge equation can use the functions in the manual, or you can add
your own as needed. It is possible to use "x", "y", or "z" in your
expression to have a spatial dependence.

Thank you for trying the software. Please let me know if you have any
additional questions.

Regards,

Juan

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