Correlation of cathodoluminescence and EBIC contrast in GaAs/AlxGa1-xAs quantum well structures

Combined CL and EBIC investigations are performed to specify the electronic properties of a p-i-n GaAs/AlxGa1-xAs quantum well structure grown by molecular beam epitaxy on a (100)GaAs substrate miscut by 2 degrees towards (1 (1) over bar 1)As. For particular growth conditions, distinct corrugations of the layer system evolve, which are accompanied by composition variations within the barriers and thickness fluctuations of the quantum well. The patterns of EBIC images are strongly anti-correlated with the CL intensity distribution obtained for a detection energy, which corresponds to the low-energy side of the barrier CL spectrum. Both signals arise from the intrinsic part of the layer stack and indicate lateral inhomogeneities of the vertical carrier transport due to barrier regions with low AlAs mole fraction.