Carrier lifetime control by intentional boron doping in aluminum doped p-Type 4H-SiC epilayers

Abstract

The carrier lifetime control in p-Type 4H-SiC epilayers with intentional aluminum (Al) and boron (B) doping is demonstrated as part of work to develop a p-Type "recombination-enhancing layer"for n-channel insulated gate bipolar devices fabricated on p-Type substrates. The (Al + B)-doped epilayers (Al: 5 × 1017, B: 4 × 1016 cm-3) showed a very short minority carrier lifetime of less than 20 ns at 293 K, resembling that of highly Al-doped epilayers (Al: 1 × 1019 cm-3). Besides, the minority carrier lifetimes in (Al + B)-doped epilayers are stable against post-Annealing in Ar and H2 ambient, while that of Al-doped epilayers varied considerably. PiN diodes with a 10 μm-Thick (Al + B)-doped buffer layer inserted on p-Type substrates showed no evident degradation after a stress test under a pulse current density of 2000 A/cm2.