Tao
July 22, 2022, 3:07am
#1
Dear DEVSIM developer，

Recently, I want to achieve “impact avalanche generation” in DEVSIM. I have a basic question:

As we know the impact avalanche generation rate is calculated:

G = \alpha_{n} \frac{|J_{n}|}{q} + \alpha_{p} \frac{|J_{p}|}{q}

\alpha_{n} and \alpha_{p} are impact ionization coefficient from model. They are electricfield-dependent and as EdgeModel in DEVSIM.

```
CreateEdgeModel(device,region,"Ion_coeff_n",Ion_coeff_n)
CreateEdgeModel(device,region,"Ion_coeff_p",Ion_coeff_p)
```

The impact avalanche generation rate G is a function of the |J_{n}| and |J_{p}| , but |J_{n}| and |J_{p}| are EdgeModel variables to be solved in DEVSIM.

How to calculate the impact avalanche generation rate G in DEVSIM? Are there any examples?

Juan
July 22, 2022, 3:13am
#2
Hi @Tao

This post from @akirt seems to be related, and would be a good basis to start a discussion:

Thanks to Juan’s efforts on developing the DEVSIM. Especially after version 1.5, a lot of models can be implemented with the support of edge/element node volume based integration.
Here I wanna share an example of Avalanche Breakdown by implementing impact ionization model.
The model comes from the work in [1]. By using the constant temperature assumption, the ionization coefficient fomula can be simplified to:
Imp_coeff = a*F_ava*exp(-(b/F_ava)^2)
where a and b are empirical parameters and F…

Tao
July 27, 2022, 8:26am
#3
Thank you a lot!
Now my script works well to simulate the impact avalanche.

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