Titanium thin film growth on small and large misfit substrates

The influence of lattice misfit on the growth of Ti (0001) is investigated in the limit of small negative (−1%) and large positive (+6.8%) misfit by choosing MgO (111) and Al2O3 (0001) as substrate materials. Reflection high energy electron diffraction imaging and intensity measurements during growth reveal two-dimensional nucleation of islands on MgO, in contrast to three-dimensional nucleation on Al2O3. X-ray analysis of 30-nm-thick films on MgO shows a two-component line shape in transverse scans of the (0002) and (0004) reflections, pointing to a high degree of structural coherence in the weak disorder limit. The surface morphology of films grown on MgO depends strongly on the substrate temperature during growth.