Structural Perfection of InGaAs/InP Strained-Layer Superlattices Grown by Gas Source Molecular Beam Epitaxy: A High-Resolution X-Ray Diffraction Study.

High-resolution X-ray diffraction (HRXRD) studies have been carried out to determine the structural perfection and periodicity for a number of high-quality InGaAs/InP strained-layer superlattices (SLS's) grown by gas source molecular beam epitaxy (GSMBE). X-ray scans were carried out with a compact four-crystal monochromator resulting in a resolution of one molecular layer (~ 3angstroms), which enables one to observe very small variations in the periodic structure. Sharp and strong higher-order satellite reflections in the XRD profiles were observed indicating smooth interfaces with well-defined modulated structures. Excellent computer simulated fits of the X-ray satellite pattern could be generated based on a kinematical XRD step model which assumes ideally sharp interfaces. Our results demonstrate that HRXRD in conjunction with the kinematical step model provides a powerful tool to evaluate the structural perfection of InGaAs/InP strained-layer superlattices.