Large-area, liftoff nanoporous GaN distributed Bragg reflectors: Fabrication and application

摘要

A facile one-step electrochemical etching based on NaNO3 solution was developed for use in the chemical lift-off nanoporous-(NP-) GaN distributed Bragg reflectors (DBRs) over a macroscopic area ( 1 cm(2)). The reflectivity of the lift-off DBR mirror is similar to 85%, which is far lower than that (similar to 97%) of the NP-GaN DBR on the sapphire substrate. The decrease should be attributed to light scattering due to higher roughness in the lift-off mirror. To study its possible applications, tris(8-hydroxyquinoline) aluminum (III) (Alq(3)) thin film was grown on transferred NP-GaN DBR mirror onto silicon substrate via a thermal evaporation deposition. Compared to the reference Alq(3) thin film, the photoluminescence of the Alq(3) thin film on the transferred mirror presents significant enhancement and slight blue-shift, which should be attributable to reflectivity enhancement by the DBR and inner channel surface in the DBR mirror, respectively.