Small-signal operation of semiconductor devices including self-heating, with application to thermal characterization and instability analysis

A rigorous mathematical treatment of dynamic self-heating in semiconductor devices is presented. Two formulations for the admittance parameters are given. The thermal behavior of the device is referred to device temperature in the first formulation, and to ambient temperature in the second. Contrary to previous work, nonlinear thermal effects are included. An analytical model for the thermal resistance is derived which confirms the relevance of these effects. Applications of the above results to device modeling and thermal characterization are studied in detail by means of numerical simulations. Possible sources of inaccuracies are evidenced. Finally, it is shown that the differential analysis of thermal feedback provides a general and rigorous means to determine the conditions for the onset of thermally-induced instabilities.