Crack-free AlGaN/GaN distributed Bragg reflectors synthesized by insertion of a thin SiNx interlayer grown on 6H-SiC substrate by metal–organic chemical vapor deposition

Abstract Crack-free AlGaN/GaN distributed Bragg reflectors (DBRs) for the near-UV region were grown on 6H-SiC substrates by metal–organic chemical vapor deposition (MOCVD). To suppress the generation of cracks, a thin SiN x interlayer was introduced between the first pair of AlGaN/GaN DBR layers. Using this approach, crack-free 30-pair Al 0.2 Ga 0.8 N/GaN DBRs were obtained with peak reflectivity of 92.8% at 388 nm and a stop-band bandwidth of 16 nm. Our results reveal that a SiN x interlayer not only decreased the tensile strain but also improved the reflectivity via suppression of cracks.