⚡ Fossum model for carrier lifetime

[marc-flex]

• Added Fossum model for carrier lifetime
• Split reference doping into n and p dopings (CaugheyThomasMobility)

This is the only thing that needed to be added to the front-end to improve the 2D results.

FYI: There will soon be a back-end PR associated to this plus some other fixes

[daquinteroflex]

Looking good!

[momchil-flex]

Looks good, but for my understanding where exactly do the specific values come from in the two separate mobility models now?

[marc-flex]

where exactly do the specific values come from in the two separate mobility models now?

The Fossum parameters can be found in the original paper by Fossum et al. The mobility model is basically the same model as before but by splitting up the entry into n and p we avoid having to duplicate naming (e.g., mu_n, mu_p)

I'll add some references.

[marc-flex]

@momchil-flex @daquinteroflex if you both are OK with this I'll merge by the end of the day

[daquinteroflex]

Makes sense to me!