LATERAL VARIATIONS OF THE QUANTUM-WELL CONFINEMENT ENERGY REFLECTED BY SEM-CATHODOLUMINESCENCE

The potential of cathodoluminescence (CL) in connection with scanning electron microscopy (SEM) for the investigation of the lateral variati on of interfaces in this film heterostructures is examined. GaAs/AlxGa 1-xAs single and multiple quantum wells were prepared by molecular bea m epitaxy under different conditions resulting in various surface morp hologies. Spectrally resolved CL line profiles, which provide informat ion on lateral variations of the exciton confinement energy (E) are co mpared with the surface structure imaged by SEM or atomic force micros copy. For surface undulations with periods larger than the spatial res olution (L) of CL, a direct correlation between surface and interface features was proven. In the case of a statistical distribution of smal l interface growth islands, the period of the CL intensity modulation is determined by L. However, the modulation depth of the CL intensity contains information on the underlaying disorder. For substrates, in w hich misfit dislocations were generated during the MBE growth of the h eterostructure, we found variations of E along two sets of straight li nes perpendicular to each other.