Investigation on the thermal stability of reflective and anti-reflective coatings on freestanding GaN

Abstract

The reflective (RC) and anti-reflective coatings (ARC) on freestanding GaN were fabricated using a stack of TiO2/SiO2 multi-layers, which changes the reflectance at 532 nm from 17.0% to 2.5% and 99.6%, respectively, and proves the effectiveness of RC and ARC. The reflection spectra of annealed RC and ARC both show a blueshift of about 52 nm after high-temperature annealing, because of the phase transition of TiO2 from amorphism to anatase at high temperatures. In order to improve the thermal stability of RC and ARC, we could increase the thickness of TiO2 and SiO2 proportionally during the coating process.