3.2.11 Impact Ionization

Impact ionization (II) as a high field generation process plays a dominant role in the understanding of HEMT device degeneration. In a first step Fig. 3.14, Fig. 3.15, Fig. 3.16, and Fig. 3.17 compile several measurements and MC data sets for III-V materials to highlight basic properties of impact ionization for several materials.

Figure 3.14: Fit of the measured impact ionization rates versus inverse field for GaAs [56].

Figure 3.15: Measured impact ionization rates versus inverse field for In$_{0.53}$Ga$_{0.47}$As [205,297].

Fig. 3.14 shows the generation for GaAs as a function of the inverse electric field using the fit of data in [56]. In Fig. 3.15 fits to the measured coefficients for In$_{0.53}$Ga$_{0.47}$As are shown for data taken from [205,297]. Earlier data in [217,218] deviate significantly.