Breaking the theoretical limit of SiC unipolar power device – A simulation study

SiC is known as the next generation material for power semiconductor devices. One important issue in the design of high voltage power devices is the trade-off between breakdown voltage and specific on-resistance. In this paper, possibility of developing 4H–SiC devices beyond its own unipolar theoretical limit RSP_ON∝VBR2.43 by using the super-junction concept has been investigated for the first time. Effects of structural parameters on the voltage blocking capability and specific on-resistance are studied. Device structures achieving optimum FOMs (Figure of Merit) at various voltage ranges have been designed and their advantages over the conventional structures are quantified. In addition, simple models have also been developed and verified by 2D numerical simulations for 4H–SiC super-junction structures to predict their voltage blocking and forward conduction capability. The results show that, with currently available technology, device FOM (for the same VBR) exceeding the 4H–SiC theoretical unipolar limit by 300% is possible.