Calculation of electron impact ionization co-efficient in β-Ga2O3

Monoclinic β-Ga₂O₃ field effect transistors (FETs) have been recently explored for power electronics application [1, 2] due to its large bandgap, and the availability of native substrates. Quantitative impact ionization coefficient (α) values are required to accurately predict the achievable breakdown voltages in these devices. Here, we first report the theoretical calculation of the electron impact ionization co-efficient in β-Ga₂O₃ by numerically evaluating the electron distribution function at high electric fields using Baraff's method [3]. We have included acoustic deformation potential (ADP) scattering, impurity scattering (IS), polar optical phonon (POP) scattering, and impact ionization (II) scattering in our calculations. Non-polar optical phonons are found to have negligible effects. Cheynoweth exponential fit of the impact ionization coefficient is extracted that can be used in device simulators to optimize the device design for high breakdown voltages.