AlGaN/AlN distributed bragg reflectors for deep ultraviolet wavelengths

Distributed Bragg reflectors with up to 21 periods consisting of AlN and Al 0.58 Ga 0.42 N layers were grown by metalorganic chemical vapor deposition. A periodic structure and good interface quality was verified by both transmission electron microscopy and X-ray diffraction, and was shown to be dependent on the composition of the underlying AlGaN base layer. Reflectivities of 49.8% at 285 nm and 66.6% at 245 nm were obtained with ten period superlattices. A reflectivity of 82.8% at 278 nm was measured for a twenty period structure.