POLYCOMPONENT OXIDE CRYSTALS: GROWTH AND APPLICATION A.Pajaczkowska¹, A.Gloubokov¹, P.Reiche², R.Uecker², ¹Institute of Electronic Materials Technology, 01-919 Warsaw, Poland, ²Institut of Crystal Growth, 12489 Berlin, Germany

Polycomponent oxides of CaNdAlO₄ (CNA), SrLaAlO₄ (SLA), SrLaGaO₄ (SLG), NdGaO₃ (NGO), LiAlO₂ (LAO), LiGaO₂ (LGO) have been found, recently, as attractive substrates for HTSC and GaN thin layers, respectively. Crystals are grown by Czochralski method and anisotropic properties of compounds play an important role in case of CNA, SLA and SLG in the growth of good quality crystals.

Morphology of these crystals depend on ionic-covalent character of bonding and crystal growth parameters. Point defects are observed in crystals and they are reflected in color changes (colorless, yellow, green). Point defects are detected in directions perpendicular to oxide planes and are connected with instability of oxygen position in lattice. Results of ESR and optical spectroscopy investigations are presented [1].

Most oxides of the same crystal structure form solid solutions which exist in solid state, however, crystal growth is only limited to very low solubility (0.1 mol% or less) these cations in host lattice. The solubility does not only depend on ionic radii but it is assumed that electron structure of cations influences the stability of crystal structure.

It is pointed out that crystal growth process of polycomponent oxide crystals by Czochralski method depends on the preparation of melt and its stoichiometry, orientation of seed, gradient of temperature at crystal-melt interface, parameters of growth (rotation and pulling rate) and control of red-ox atmosphere during seeding and growth. Growth parameters have an influence on the morphology of crystal-melt interface, type and concentration of defects.

1. M.Drozdowski, J.Domagala, M.Kozielski, M.Szybowicz, A.Pajaczkowska, Solid State Comm. 96 (1995) 785.