Quantitative rheed analysis of biaxially-textured polycrystalline MGO films on amorphous substrats grown by ion beam-assisted deposition

摘要

We have developed a computer simulation based on analytic calculation of relfection high energy electron diffraction (RHEED) patterns in the kinematic approximation for mosaic poly crystalline films for given values of electron beam incidence angle, polycrystalline texture, in-plane orientation distribution, and grain size. Although (RHEED) is most appropriately modeled using dynamical scattering theory, the computational efficiency of the kinematic approximation has enabled the development of a model suitable for real time measurement of crystallograhpic texture and in-plane orientation distributions for biaxially-textured films grown by ion beam-assisted deposition (IBAD). Using the simulation, we can quantitatively determine how RHEED spot shapes and relative intensities depend on the crystallographic texture and in-plane orientation distribution of polycrystalline films. RHEED patterns taken at 25 keV with incidence angle in the range 1-5 degrees from 10 nm thick, nominally (100)-texture MgO films grown on amorphous Si_3N_4 by IBAD were analyzed by comparing experimental RHEED phi rocking curves with those predicted by the simulation. For some films, an additional 200 nm thermally-grown MgO homoepitaxial layer was grown on top of the IBAD MgO layer. The model enables a quantitative correlation between biaxial texture and RHEED measurements. RHEED results are compared to X-ray rocking curve film analysis.