Issues regarding the multiplication model

[ggioachi]

Hi @pschutze,

thanks to you for this investigation!

@pschutze

Indeed, there was a typo with the hbarOmega, which will be fixed. However, this doesn’t change too much in the result, if the temperature is set around room temperature (at 300 K the error is cancelling out, and the result remains the same).

Yes, I understood, thanks!

I was looking at the debugging plots, found in the TransientPropagation module, and I noticed a big difference in the induced charge between holes and electrons with and without gain (I send you the plots).

Is it normal that there isn’t a difference between the two electron waveforms?

Thank again,

Giulia

[pschutze]

Hi @ggioachi ,

from my understanding this is expected. Look e.g. here: https://images.app.goo.gl/aLqMYBUeXxfFvGkL8

The reason is that the electrons from impact ionisation are generated close to the implant, hence they drift for about a micron or even less and don’t contribute too much to the signal, if the weighting potential is about linear. The additional holes, though, drift through the whole sensor depth and thus contribute with a large signal.

We have added a draft for an alternative impact ionisation algorithm:

Draft: Impact Ionization: fix typo and add probability based algorithm (!972)...

Would you be interested in testing it? In short, what you’d need to add to the TransientPropagation would be

multiplication_depth = 10  # that's more a guess, can be increased
multiplication_probability_based = true

Cheers
Paul

[cferrero]

Dear @pschutze,

thanks a lot for your suggestion!
we’re testing your new Impact Ionization algorithm and we can confirm that we obtain some better result. In the following plot you can find 3 average waveforms with no gain (green), Van Overstraeten-De Man Model (blue) and Okuto-Crowell Model (red), with the additional parameters multiplication_depth and multiplication_probability_based, as you suggested to use.

Let’s keep in touch for further updates.
Cheers,
Chiara

[pschutze]

Dear @cferrero ,

this looks like nice progress, thank you very much!

Can you comment on how this relates to what you would expect in terms of sensor current / amplification?

Cheers
Paul

[cferrero]

Dear @pschutze,

from the TCAD simulation we expected a maximum current value around 6uA (with Van Overstraeten-De Man model) and we would like to tune our Monte Carlo simulation to have an output as similar as possible to the one from the TCAD. We can also discuss about this offline,
thanks a lot for all your work!!

Chiara