GaAs/GaAlAs surface emitting IR LED with Bragg reflector grown by MOCVD

Abstract

Abstract Surface emitting GaAs/GaAlAs diodes with a Bragg reflector grown by metalorganic chemical vapor deposition (MOCVD) were investigated. They have a double heterostructure and a Bragg reflector consisting of 25 pairs of Ga 1− x Al x As/GaAs multilayers ( x = 1 or 0.45) between the GaAs substrate and the cladding layer. Since the light is reflected by the Bragg reflector, the absorption by the substrate can be avoided and high external quantum efficiency is achieved. The emission spectra are, however, oscillating as a result of the interference of the light reflected by the emitting surface and by the Bragg reflector. The oscillation was removed by coating an anti-reflecting layer on the surface. An output light power of 8 mW operated at 50 mA was obtained, which is four times higher compared with the case of no Bragg reflector.