# Impact Avalanche Generation in Diode Example

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?

Hi @Tao

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

Thank you a lot!
Now my script works well to simulate the impact avalanche.

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