MOCVD Approach to the Growth of Calcium Copper Titanate (CaCu_3Ti_4O_(12)) Thin Films: The Role of the Substrate Nature on Film Structural and Dielectrical Properties

摘要

CaCu_3Ti_4O_(12) (CCTO) perovskite has been widely investigated because of its excellent dielectric properties, i.e. huge and constant permittivity upon varying temperature and frequencies, which are really attractive in wireless communication devices. These characteristics have been originally demonstrated in single crystals and ceramics. Hence, huge efforts have been focused on the fabrication and investigation of CCTO thin films. First attempts have been performed by pulsed laser deposition technique, nevertheless the chemical vapor deposition methods are preferred for large area industrial production. In this context, here is described the Metal Organic Chemical Vapor Deposition (MOCVD) approach for the growth of CCTO complex oxide. High quality CCTO thin films are fabricated on several substrates, varying from single crystals (LaAlO_3 and SrTiO_3) to electrodes (Pt and IrO_2). The present MOCVD process is based on a molten mixture of the Ca(hfa)_2?tetraglyme, Ti(tmhd)_2(O-iPr)_2, and Cu(tmhd)_2 precursors as multi-component source. The deposited CCTO films are epitaxial on single crystal substrates, while polycrystalline films have been found on metal electrodes. A correlation among structural/morphological properties of CCTO films with deposition conditions and substrate nature is discussed. Moreover, the effects of the structural properties on the dielectric properties are also investigated.