In-situ Al: Ti-co-doped La3 Ga5.5 Ta0.5O14 films for High-Q Resonators

High-quality single-crystalline La₅Ga_5.5Ta _0.5O₁₄ (LGT) films, in-situ co-doped with Al and Ti, have been grown by liquid phase epitaxy (LPE) on LGT substrates. The chemical composition of the films and substrates was analyzed by secondary ion mass spectroscopy (SIMS) and Rutherford back scattering (RBS). The abrupt change of dopant concentration at the substrate-film interface allow a precise measurement of film thickness, typically 0.5 to 2 mum, for given growth conditions. Quantitative SIMS was performed by using Al/Ti ion-(co)-implanted LGT substrates as standards. The Al and Ti dopants are extremely homogeneously distributed, and their concentration is constant within the film thickness. The concentration of the constituent ions (La, Ga, Ta) in the LGT substrates and in the doped LGT films are slightly different. In-situ doping of LGT LPE films by selected ions can potentially be used to adjust the materials properties to specific bulk and surface acoustic wave applications requirements