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

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: 5x10(17), B: 4x10(16)cm(-3)) showed a very short minority carrier lifetime of less than 20ns at 293K, resembling that of highly Al-doped epilayers (Al: 1x10(19)cm(-3)). Besides, the minority carrier lifetimes in (Al+B)-doped epilayers are stable against post-annealing in Ar and H-2 ambient, while that of Al-doped epilayers varied considerably. PiN diodes with a 10 mu m-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 2000A/cm(2).