Physical modeling of SiC devices based on the optical characterization of their internal electrothermal behavior

While the material and process technologies for SiC devices are becoming steadily more mature, the predictive simulation of SiC devices still lacks the availability of accurately calibrated physical device models. Basically it is feasible to adopt the physical models describing silicon devices for the analysis of SiC devices, but it is indispensable to recalibrate the model parameters. A reliable calibration requires measured and simulated data that can be one-to-one related to each other. But while experimental data mostly refer to the terminal behavior of the device under test, simulations can also provide insight into the "innerelectronic" behavior. In view of the device physics underlying the electrothermal behavior of devices, the spaceand time-resolved electron and hole concentrations as well as the temperature distribution are among the most interesting quantities. This paper presents an optical diagnosis method that combines free carrier absorption measurements, which yield time-resolved electron and hole density profiles from bipolar devices during turn-on and under stationary conditions, and light deflection measurements, which provide information about the gradients of the electron and hole densities as well as that of the temperature gradient. The measurement and the model calibration are exemplified by considering samples of 4H-SiC 6.5 kV bipolar diodes with a thickness of the intrinsic region of 70 ¿m. In particular, the calibration is focused on the physical models of incomplete ionization of dopants, carrier mobility, and Shockley-Read-Hall recombination.