Impact Ionization Generation
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.
Recombination and Generation and Theory for Impact Ionization
The carrier generation rate due to impact ionization is given by:
The values of αn and αp can be user-defined or can be related to the material properties in the following manner:
where and are the components of the electric field parallel to the electron and hole currents respectively and Tref, an, ap, bn, bp, dn, and dp are material properties.
Impact Ionization Generation
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 default Temperature reference Tref is 300 K.
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.
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a factor, electrons, impact ionization an (SI unit: 1/V). The default is 0.426 (1/V).
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a factor, holes, impact ionization ap (SI unit: 1/V). The default is 0.243 (1/V).
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b factor, electrons, impact ionization bn (SI unit: V/m). The default is 4.81·105 V/cm.
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b factor, holes, impact ionization bp (SI unit: V/m). The default is 6.53·105 V/cm.
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c factor, electrons, impact ionization cn (SI unit: 1/K). The default is 3.05·10-4 (1/K).
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c factor, holes, impact ionization cp (SI unit: 1/K). The default is 5.35·10-4 (1/K).
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d factor, electrons, impact ionization dn (SI unit: 1/K). The default is 6.86·10-4 (1/K).
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d factor, holes, impact ionization dp (SI unit: 1/K). The default is 5.67·10-4 (1/K).