Carrier Recombination in n-Type 4H-SiC Epilayers with Long Carrier Lifetimes

A longest carrier lifetime of 33.2 µs was achieved by eliminating the Z1/2 center via thermal oxidation at 1400 °C for 48 h and subsequent surface passivation with a nitrided oxide on a 220-µm-thick n-type 4H-SiC epilayer. By deep-level elimination, photoluminescence (PL) in the infrared region (wavelength: 700–950 nm) was remarkably enhanced at locations of threading dislocations. A threading screw dislocation exhibited much stronger infrared PL than a threading edge dislocation. The present results indicate that carrier recombination at extended defects becomes pronounced through the elimination of the Z1/2 center in the epilayers.