Modeling of the hot electron subpopulation and its application to impact ionization in submicron silicon devices-Part I: transport equations

Impact ionization (II) in three different n/sup +/-n/sup -/-n/sup +/ device structures is investigated using self-consistent Monte Carlo simulations. A subset of electrons participating in II-referred to as the hot electron subpopulation (HES)-is identified. The data obtained from the Monte Carlo (MC) simulations indicate that the average energy of the HES (/spl omega//spl tilde/) is an appropriate variable for the macroscopic quantification of II in all the devices under consideration. In order to calculate /spl omega//spl tilde/, a set of macroscopic transport equations for the HES is derived from the Boltzmann transport equation and calibrated using data from the MC simulations. Numerical solutions to the proposed II model applied to the three devices considered here will be presented in Part II. Therein, values of the II coefficient (IIC) predicted by our model will be compared to those obtained from our MC simulations and also to IIC values predicted by models proposed earlier by other authors.>