An Impact Ionization Model Including an Explicit Cold Carrier Population

Conventional macroscopic impact ionization models which use the average carrier energy as main parameter can-not accurately describe the phenomenon in modern miniatur-ized devices. Here we present a new model which is based on an analytic expression for the distribution function. In partic-ular, the distribution function model accounts explicitly for a hot and a cold carrier population in the drain region of MOS transistors. The parameters are determined by three even mo-ments obtained from a solution of a six moments transport model. Together with a nonparabolic description of the den-sity of states accurate closed form macroscopic impact ion-ization models can be derived based on familiar microscopic descriptions