Metal-organic chemical-vapor deposition of high-reflectance III-nitride distributed Bragg reflectors on Si substrates

High-reflectance group III-nitride distributed Bragg reflectors (DBRs) were deposited by metal-organic chemical-vapor deposition on Si(111) substrates. A reflectance greater than 96% was demonstrated for an AlN∕GaN DBR with a stop band centered in the blue-green range of the visible spectrum. Crack-free GaN cap layers were grown on the DBR structures to demonstrate the opportunity to build III-nitride optoelectronic devices in this material. The DBR structure was under significant strain due to growth on a mismatched substrate, although the GaN cap layer was shown to be strain-free.