Carrier Injection and Transient Mode Problem?!


Hi to all,

I have a problem in DEVICE simulation and I’ll be glad to make my way with your helps.

At first, I imported the electron-hole carriers profile from FDTD to DEVICE. When I use the steady state mode, I face no problems, but in the transient mode I want to multiply this carriers profile to a function of time as appeared below, to get a profile in the form of G(x,y,z,t).

I want to have all the values of current and carrier profiles at the output after applying the mentioned profile. But the problem is that the calculation of output is just in the ranges of (t_on , t_slew+t_off), and I want to see the changes after the carrier conjunction ends.
The expected answer was about 0 to 500 or 600 fs , but it resulted in 100 to 320 fs .

Thanks in advance…

Best regards


Hi @ifariborz,

There are few points to mention here.

  1. The minimum time step should not be less than 1 ps or at least 500 fs. This limitation comes from the fact that the drift-diffusion solver always assumes that the carriers are at thermal equilibrium. At very small time steps this assumption is not valid.

  2. The end time of your simulation is determined by the maximum time you have defined in your simulations. This is the maximum time you have defined in the simulation setup, either in the electrical contacts or in the global shutter. In most cases this should be defined at the electrical contact boundary condition. You should have at least one electrical contact whose bias is transient and the end time of your voltage table tells the solver how long to run the simulation.

I am guessing that you do not have a “transient” definition of the electrical contacts in your simulation so the solver is taking the maximum time in the definition of the shutter as the simulation end time.


Thank you @aalam
I will take a better look at my simulation.