Discussion Forum

Hi all,
I am relatively new to comsol and I am looking for help.

I am trying to adjust the geometry of on of demo models. It is model 114,
the semiconductor diode. I want a more symmetric model.
First, I deleted the old boundary consisting of a straight line and a
curve line. then I replaced that boundary with a line going from one end of
the diode to the other. then, I remeshed it by including boundaries
5,6,4,2. I also took note of the equations shown in variable 1 under
definitions. I graphed N, p_init, n_init, and psi_init in matlab. The
graphs make sense, as in they vaguely resemble the original output. if you
comment out lines 24, 26, 27, 28 in the matlab code. You will have my
equation. If you look at the results of that equation. The graphs look
really similar to the original graph expect the p side of the diode is all
the way across the diode.
>The solution does not solve. What am I doing wrong? I even expanded the
boundary of the contact so it covers the entire top boundary(5, 6). I
included cn and pn for those same boundaries. It seems odd that comsol was
able to solve the diode when it was not symmetrical and now i just extended
the p region to all the way across the diode and the diode does not solve.

thanks in advance