On the TCAD Based Design Diagnostic Study of 4H-SiC Based IGBTs

This paper addresses the design diagnostic study of 4H-SiC based IGBTs using two dimensional numerical computer simulations. Using identical set of physical device parameters (doping, thicknesses), simulated structure was first calibrated with the experimental data. A minority carrier life time in the drift layer of 1.0 1.6 μs and contact resistivity of 0.5 - 1.0 x 10-4 Ω-cm2 produces a close match with the experimental device. A decay in the device transconductance and threshold voltage is observed with increasing temperature. The on-resistance first decays with temperature (i.e., increased in ionization level, and increase in minority carrier life time), stays nearly constant with further increase in the temperature (may be all carriers are now fully ionized and increase in carrier life time is compensated with decrease in the carrier mobility) and finally increases linearly with temperature (> 450 K) due to decrease in the carrier mobility. The design of buffer layer is investigated that shows lower on-state losses with thin high doped buffers. For the design of devices over 15 20 kV, the design of drift layer demands a doping of < 2.0 x 1014 cm-3 with epitaxial layer quality giving a carrier life time over 2.0 μs.