Determination of Effective Critical Breakdown Field in 4H-SiC Superjunction Devices

We determine the effective critical breakdown field for 4H-SiC superjunction (SJ) devices and compare it to their conventional counterparts. Also, we investigate its dependence on SJ device structural parameters, such as drift layer thickness (t) and pillar width (W). In 4H-SiC SJ devices, the effective critical breakdown field was found to be around 30% lower than that of conventional devices owing to their longer ionization paths. In particular, the effective critical electric field varies as ξ cr α t -1/10 and ξ cr α t -1/6 for 4H-SiC SJ and conventional devices respectively but independent of pillar width and doping concentration for high aspect ratio devices (t/W > 10).