Improvement of 4H-SiC Power p-i-n Diode Switching Performance Through Local Lifetime Control Using Boron Diffusion

A comparison is carried out of the switching characteristics of 4H-SiC conventional p-i-n rectifiers, where the p-layer is formed by aluminum doping during epitaxial growth, with that of p-i-n diodes, where the p-layer is formed by codiffusion of aluminum and boron. It is demonstrated that p-i-n diodes that are produced by high-temperature diffusion exhibit better switching capability as compared to epigrown p-i-n diodes. The improved behavior is attributed to the reduced lifetime region that is created by the diffused boron layer. Also, the reduced lifetime region was implemented in a SiC conventional epitaxial p-i-n structure by boron diffusion through the epitaxial aluminum-doped p⁺ layer; the switching behavior of such a "hybrid" p-i-n diode is identical to that of the diffused one. The improvement of reverse-recovery characteristic is attributed to the effect of localized lifetime control by recombination centers that are created by diffused boron