Comprehensive characterization of MOVPE-grown AlGaAs/AlAs distributed Bragg reflector structures by optical reflectance, X-ray diffraction and atomic force microscopy

This paper reports on a comprehensive characterization of MOVPE-grown AlxGa1−xAs/AlAs distributed Bragg reflector (DBR) structures via optical reflectance, X-ray diffraction (XRD) and atomic force microscopy (AFM). These analytical techniques are used to investigate the influence of parameters like substrate misorientation, aluminum content and number of mirror pairs on the characteristics of high-reflectivity AlxGa1−xAs/AlAs-based Bragg mirrors. We find a strong correlation between the optical reflectivity of the DBR mirrors and the quality of X-ray rocking curves as well as the surface/interface roughness as measured by AFM. The data provided by these analytical techniques are used to optimize the DBR performance for its application in visible-wavelength vertical-cavity surface-emitting laser (VCSEL) diodes.