High-precision characterization of super-multiperiod AlGaAs/GaAs superlattices using X-ray reflectometry on a synchrotron source

The morphology of Al$_{0.3}$Ga$_{0.7}$As/GaAs superlattices grown by molecular beam epitaxy was determined by X-ray reflectometry (including a synchrotron radiation source) and photoluminescence. The thicknesses of the superlattice layers with 100 periods, found using laboratory and synchrotron studies, correlate with an accuracy of $\sim$1%. At the synchrotron, beginning with high ($>$ 4 – 5) Bragg orders, reflection peaks were found that are not observed in measurements with a diffractometer and are apparently associated with the technological features of the growth of such structures. It follows from the analysis that the peaks correspond to modulation in the superlattice with a period 3 – 5 times greater and characterize the scatter of the thicknesses over the structure depth by several percent.