This paper describes the effect of variation of energy relaxation time on temperature distribution of power Si MOSFET in electro-thermal analysis. In previous our studies, thermal properties of power Si MOSFET are evaluated using electro-thermal analysis. However, in our previous calculation, energy relaxation time has been assumed to be constant at 0.3 ps, which is widely used value in electro-thermal analysis. This is because energy relaxation time cannot be calculated by classical physics, and it is difficult to detect exact energy relaxation time. However, energy relaxation time is important for evaluating heat generation in electro-thermal analysis. One method to obtain energy relaxation time is Monte Carlo simulation. In this research, we performed Monte-Carlo simulation, and electrical field and lattice temperature dependencies of energy relaxation time were evaluated. Then, we performed electro-thermal analysis of power Si MOSFET with various energy relaxation times, and the effect of change of energy relaxation time on temperature distribution of power Si MOSFET in electro-thermal analysis was discussed. Energy relaxation time in the range of 0.1–1000 kV/cm of electrical field was evaluated in Monte Carlo simulation. The results of Monte-Carlo simulation showed that maximum energy relaxation time becomes about 0.6 ps, and minimum energy relaxation time is about 0.30 ps. Following the results, to investigate the effect of variation of energy relaxation time on temperature distribution of power Si MOSFET, we changed energy relaxation time in electro-thermal analysis, and thermal properties of power Si MOSFET was calculated. The results of electro-thermal analysis showed that energy relaxation time has an effect on temperature distribution of power Si MOSFET. Therefore, accurate energy relaxation time should be considered in electro-thermal analysis for appropriate temperature distribution of power Si MOSFET.
Analysis of saturation velocity and energy relaxation time of electrons in Si using full‐band Monte Carlo simulation
