Impact Ionization Generation occurs when, for example, an energetic electron undergoes a collision in which it loses sufficient energy to promote an electron in the valence band to the conduction band, resulting in an additional electron hole pair being produced. It is the mechanism responsible for avalanche breakdown. Select this option from the
Generation-Recombination submenu.
The values of αn and
αp can be user-defined or can be related to the material properties in the following manner:
If the check box is selected, then additional degrees of freedom are created for the generation rate. This allows the use of the Previous Solution node in the solver sequence to delay the update of the generation rate, which helps convergence at the expense of the accuracy of the solution (take smaller steps to check the accuracy).
The default Impact Ionization model is
Okuto-Crowell model. For
User defined, enter a desired value or expression in the input field for the values of
αn and
αp.
For the Okuto-Crowell model, the defaults for the following are all taken
From material. For
User defined, enter a different value or expression in the text field.