Characteristics of a distributed Bragg reflector for the visible-light spectral region using InGaAlP and GaAs : comparison of transparent- and loss-type structures

Distributed Bragg reflectors (DBRs) for the visible-light spectral region constructed by InAlP/InGaAlP pairs and InAlP/GaAs pairs, grown by metalorganic chemical-vapor deposition, have been investigated with the point of comparing optical and structural properties. In the case of the InAlP/InGaAlP stacked type, a reflectivity above 80% has been realized; however, the bandwidth decreased by shortening the peak wavelength. The reflection spectrum of the InAlP/GaAs DBR showed a wide-band characteristic and provided a relatively high reflectivity to the green region in spite of the absorption loss of the GaAs layers. These results were in good agreement with theoretical calculations considering the absorption loss and refractive index of individual stacked layers. These DBRs have also been confirmed to have good uniformity and periodicity through cross-sectional transmission electron microscopy and x-ray rocking curve analysis. Good electrical conductivity through these DBRs has been obtained for the n-type structure.