RESUMEN
An algorithm is proposed for determining the orientational relationships and crystal unit-cell parameters of thin films using a laboratory X-ray diffractometer and stereographic projections. It is illustrated by the treatment of experimental data obtained for yttrium orthoferrite YFeO3 films on single crystalline sapphire (Al2O3) substrates for film thicknesses in the range from 100 to 7000â Å. Precise determination of unit-cell constants and angles is possible by combining the results of X-ray measurements made in the in-plane and out-of-plane geometries. The unit-cell unit parameters and orientation relationships for thin films were determined. For the studied films, typical errors in determining unit-cell parameters and angles are better than 0.17â Å and 0.17°, respectively.
RESUMEN
The ferromagnetic semiconductor EuO is believed to be an effective spin injector when directly integrated with silicon (Si). Injection through spin-selective ohmic contact requires superb structural quality of the interface EuO/Si. A recent breakthrough in manufacturing free-of-buffer-layer EuO/Si junctions calls for structural studies of the interface between the semiconductors. The synthesis of EuO employs an advanced protection of the Si substrate surface and a two-step growth protocol. It prevents unwanted chemical reactions at the interface. Ex situ high-resolution x-ray diffraction (XRD) and reflectivity (XRR) accompanied by in situ reflection high-energy electron diffraction reveal direct coupling at the interface. A combined analysis of XRD and XRR data provides a common structural model. The structural quality of the EuO/Si spin contact far exceeds that of previous reports and thus makes a step forward to the ultimate goals of spintronics.