Interface dilution and morphology of CdTe/MnTe superlattices studied by small- and large-angle x-ray scattering

We have performed small- and large-angle x-ray scattering experiments on Cd Te/MnTe superlattices. The Fresnel optical method and the distorted wave Bo rn approximation were used to extract from small-angle measurements out-of- plane and in-plane information about the interfaces. Specular reflectivity shows that the interface roughness is quite high (about 7 Angstrom) for all superlattices. The effective MnTe concentration, directly determined from the refractive index profile, is successfully used to simulate the structur ed nonspecular scattering, and to determine the lateral correlation length of the interface roughness (about 1500 +/- 750 Angstrom). Moreover, it is s hown that the layers are almost completely correlated over the sample thick ness. The thickness fluctuations along the growth direction are estimated f rom the analysis of the large-angle (004) reflection, and the effective MnT e profile is also checked by dynamical simulation. It is shown that the sma ll- and large-angle results are in good agreement. The MnTe profile width d educed from x-ray reflectivity is slightly overestimated due to the large i ntegration area of this technique. An estimation of the local MnTe profile is given. (C) 2000 American Institute of Physics. [S0021-8979(00)07310-2].