Characterisation of MBE grown II-VI semiconductor thin layers by X-ray interference

X-ray interference (XRI) is a simple and powerful technique used to characterise thin layers buried within epitaxial films of GaAs/AlGaAs and InGaAs/GaAs. XRI measurements are double crystal rocking curves made on structures of the type A/B/C/B, where A is the substrate, B a different semiconductor and C the thin layer of interest, (possibly the same as A). B/C/B forms an X-ray interference film with the thicknesses of B much greater than that of C. Here, the Pendellosung fringes from B are strongly modulated by the introduction of C. XRI is also ideal for investigating materials which can not be grown thick enough for DEKTAK measurements, in which the lattice constant is not known accurately, or the layer is unstable in air and must be capped.