HTS THIN-FILMS BY INNOVATIVE MOCVD PROCESSES

The successful achievement of high temperature superconductor (HTS) YB a2Cu3O7 films by MOCVD is not straightforward and depends critically o n the volatility and stability of the precursor materials which must b e transformed into the product film. In the present study, new deposit ion processes based on mixed Liquid sources are described, where the u nstable precursor is preserved from thermal decomposition and where th e film growth rates can be considerably improved, For the synthesis of YBa2Cu3O7, these processes, named aerosol-assisted MOCVD, injection M OCVD and band-injection MOCVD, use a single solution source of Y, Ba. and Cu beta-diketonates dissolved in suitable organic solvents. Experi mental details of these new processes an described and the effects of different process parameters are studied in relation with the quality of the deposited layers. Thin and thick films of YBa2Cu3O7 and buffer layers (CeO2, SrTiO3,.....) have been grown using these processes. The superconducting properties of the high quality films obtained (T-c =9 0 K, J(c)>10(6) A cm(-2) at 77 K) will be discussed in view of their u se for large scale applications.