High quality, epitaxial TlBaCaCuO films on MgO and sapphire substrates will be prepared. However, some problems exist for such epitaxial growth and it is proposed to overcome these difficulties by buffering the substrate using an inert epitaxial layer, which has a close lattice match to the TBCCO structure. Growth of epitaxial Tl-based films via an established post deposition annealing process on top of thin, high quality CeO2 buffer layers will be undertaken. If successful, this process could replace much of the material currently grown on LaAlO3 for microwave components at high frequencies where frequency settability is a key issue.
