Entwicklung und Aufbau einer neuartigen MOCVD-Anlage zum Wachstum ferroelektrischer Duennschichten

This thesis deals with the production of ferroelectric thin films using the MOCVD technology. The main focus is put on the design and construction of a complete MOCVD research system that is equipped with a novel non-contact vaporizer system. The precursors are nebulized in an ultrasonic atomizer and injected into a hot gas stream, so they can vaporize without getting into contact with a hot surface. Hence, one of the biggest disadvantages of conventional vaporizer concepts, the contamination of the vaporizing element with decomposing chemicals, could be avoided completely, resulting in a nearly maintenance-free system. In a direct comparison with the well-established Direct Liquid Injection Subsystem DLI-25C from MKS Instruments, the advantages of non-contact evaporation were clearly demonstrated. Additionally, the scope of this work included the development of standard deposition processes for the ternary oxides SrTiO_3, BaTiO_3 und PbTiO_3 and growth studies were performed. Electrical measurements performed on MIM structures with Pt electrodes and SrTiO_3 as dielectric indicate a high film quality comparable with results presented in the literature. Furthermore, for the first time the solid solution (Pb_xBa_1_-_x)TiO_3 has been deposited by MOCVD. This material system is widely unknown in thin film form and it is well suited as a model system to investigate the influence of mechanical stresses on the film properties, because it represents a transition between the (as a thin film) superparaelectric barium titanate and the ferroelectric lead titanate. Through variation of the lead/barium ratio the tetragonal distortion of the lattice cell could be adjusted in a wide range. (orig.)SIGLEAvailable from TIB Hannover: RA 831(3956) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman