New Models for Impact Ionization in Submicrometer Devices

Limitations of different well-known impact ionization models are presented. Monte Carlo (MC) programs for both electrons and holes are used to study the impact ionization spatial-transient effects in silicon. Based on the MC simulations´ results, different experimental values of impact ionization coefficients are evaluated. Compact and efficient analytical models are developed to calculate the impact ionization current gain and noise in submicrometer devices. In deep submicrometer devices, whereas any models that involve approximations of dead spaces become less reliable, the models derived in this paper are still valid. These models can significantly reduce computational efforts when implementing in numerical approaches such as MC simulations.