ABSTRACT
The interface roughness of AlGaAs/AlAs distributed Bragg reflectors used for vertical-cavity surface-emitting lasers was investigated using atomic force microscopy (AFM), optical reflectivity, X-ray diffraction and high resolution transmission electron microscopy (HRTEM). Since the measurement of optical reflectivity and X-ray diffraction gives only a mean value for roughness for all interfaces of the structure, HRTEM investigations were carried out on cross section prepared samples. Furthermore, a special preparation technique was applied to make the AlGaAs interfaces accessible for AFM measurement. As a result it was possible to show the dependence of the interface roughness on layer number and substrate orientation.
