Study of GaN-based step-doping superjunction CAVET for further improvement of breakdown voltage and specific on-resistance

A novel GaN-based step-doping superjunction current-aperture vertical electron transistor (SD-SJ CAVET) with SD n- and p-pillars is proposed and demonstrated by two-dimensional numerical simulations. Compared with the conventional GaN-based SJ CAVET, the greater doping concentration and more uniform electric field distributions can be realized in SD-SJ CAVET based on the special structure features, leading to the further improvement in both breakdown voltage (BV) and specific on-resistance (RonA). Optimized results for SD-SJ CAVET with three doping parts in n- and p-pillars show that the increase in BV is ∼30% and the reduction of the corresponding RonA can be improved from 10.6% to 31.1%, with NN,1 (the doping concentration of the part N1 in n-pillar) decreasing from 1.5 × 1016 to 0.5 × 1016 cm−3, compared with SJ CAVET under the same aspect ratio. And further reduction in RonA can be achieved by adding differently doped layers in n- and p-pillars without obvious deterioration in BV. This SD-SJ CAVET can be fabricated by selective area growth technology.