In situ biaxial texture analysis of MgO films during growth on amorphous substrates by ion beam-assisted deposition

We used a kinematical electron scattering model(1) to develop a RHEED based method for performing quantitative analysis of mosaic polycrystalline thin film. in-plane and out-of-plain grain orientation distributions. RHEED based biaxial texture measurements are compared to X-Ray and transmission electron microscopy measurements to establish the validity of the RHEED analysis method. MgO was gown on amorphous Si3N4 by ion beam-assisted deposition (IBAD) using 750 eV Ar+ ions and MgO e-beam. evaporation. The ion/MgO flux ratio was varied between 0.66 and 0.42. In situ RHEED analysis reveals that during nucleation the out-of-plane orientation distribution is very broad (almost random), but narrows very quickly once well-oriented grains reach a critical size. Under optimal conditions a competition between selective sputtering and surface roughening yields a minimum out-of-plane texture at about 100 A, which degrades with increasing film thickness. The narrowest in-plane orientation distribution (5.4degrees FWHM) was found to be at an ion/MgO flux ratio between 0.55 and 0.51, in good agreement with previous experiments. The systematic offsets between RHEED analysis and X-ray measurements of biaxial texture, coupled with evidence that biaxial texture improves with increasing film thickness, indicates that RHEED is a superior technique for probing surface biaxial texture.