Abstract
Avalanche breakdown can occur during switching of power devices and is difficult to simulate due to its abrupt onset and strong nonlinear behavior. In addition, it severely degrades the numerical robustness of deterministic solvers for the Boltzmann equation (BE), on which the transport simulations are based. A continuation method is therefore introduced, with which robust and efficient simulation of avalanche breakdown is possible. To this end, the generation rate of the secondary electron/hole pairs due to impact ionization is multiplied with a parameter $\alpha $ . Due to this new degree of freedom in the transport equation, voltage as well as current can be specified simultaneously. The final solution is obtained by modifying the voltage or current in such a way that this parameter $\alpha $ becomes one. This approach stabilizes the simulation, improves the numerical robustness of the discrete BE, and avoids divergent solutions. Furthermore, efficient frozen-field simulations of avalanche breakdown become possible. The results are presented for a 1-D p-n junction and a 2-D vertical power MOSFET.
Highlights
I N POWER CIRCUITS, the energy stored in the magnetic field often drives the switching device into avalanche breakdown, when it is turned off [1]
This paper focuses on the problems regarding the simulation of avalanche breakdown, which is due to the secondary electrons and holes generated by II
We have demonstrated a new approach based on numerical continuation for the simulation of avalanche breakdown, where the voltage and breakdown current can be specified by introducing a multiplier for the II generation rate of the secondary electron/hole pairs
Summary
I N POWER CIRCUITS, the energy stored in the magnetic field often drives the switching device into avalanche breakdown, when it is turned off [1]. The usual approach to solve the BE is the stochastic Monte Carlo method, which is inherently transient [4] While this method has many advantages, it is too slow to simulate avalanche breakdown in power transistors. Afterwards, the avalanche breakdown starts and it takes more than 200 ps to reach a stationary state Such time scales are unattainable by Monte Carlo simulations of 2-D power devices, and different methods, which allow the direct calculation of the stationary state, are required. Another problem is the extreme steepness of the stationary current–voltage (I –V ) relation in the case of avalanche breakdown (Fig. 2).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
