CHARACTERISTICS OF A DISTRIBUTED-BRAGG-REFLECTOR FOR THE VISIBLE-LIGHT SPECTRAL REGION USING INGAALP AND GAAS - COMPARISON OF TRANSPARENT-TYPE AND LOSS-TYPE STRUCTURES

Distributed Bragg reflectors (DBRs) for the visible-light spectral reg ion constructed by InAlP/InGaAlP pairs and InAlP/GaAs pairs, grown by metalorganic chemical-vapor deposition, have been investigated with th e point of comparing optical and structural properties. In the case of the InAlP/InGaAlP stacked type, a reflectivity above 80% has been rea lized; however, the bandwidth decreased by shortening the peak wavelen gth. The reflection spectrum of the InAlP/GaAs DBR showed a wide-band characteristic and provided a relatively high reflectivity to the gree n region in spite of the absorption loss of the GaAs layers. These res ults 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 perio dicity 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.