The Valdinoci Temperature Dependent Impact Ionization Model for Silicon

Introduction

Impact ionization plays an important role in the design of many semiconductor devices. Since impact ionization is both temperature and electric field dependent, it is important to use a model which has the correct functional behavior. For most devices impact ionization defines the safe region of operation within a moderate range of temperatures, so the temperature dependence of impact ionization is of lessor importance than the field dependence. However, for devices which must operate outside of the usual temperature limits, or which carry enough current to heat themselves out of those limits, both field dependence and temperature dependence of the model must be accurate.

Impact ionization has been measured and modeled extensively at room temperature. Recently, Valdinoci et al.[1], have extended the measured temperature range to 400°C and developed a compact model for both electron and hole impact ionization. Their analytic model is given by