High-Quality LGS-Type Crystals and Films for Surface Acoustic Wave Applications

The aim of this project was to investigate the feasibility of liquid phase epitaxy (LPE) for the growth of high-quality langasite-type films for high-frequency RF resonator applications. The work done during this period included phase diagram studies, the search for a suitable solvent, systematic flux growth experiments of LGS, LGN and LGT, X-ray analysis of crystallized phases, preparation (orientation, sawing, polishing, etching) of LGS and LGT substrates from provided bulk Czochralski-grown crystals, top-seeded solution growth (TSSG) and LPE experiments. LPE films of LGS up to 1 x 1 sq cm could be grown on X- and Y-cut (YZ, XZ in-plane axis, respectively) LGS substrates for the first time. The clear tendency to step/facet formation observed on Y-LGS films indicates that this plane (at least) may evoluate to the equilibrium facet, e.g.; a perfectly oriented and flat surface, which is very interesting in view of SAW & BAW applications. Text in English.