Chemical vapor deposition of YBa{sub 2}Cu{sub 3}O{sub x} in a cold plasma reactor using an aerosol vaporization technique

A plasma-enhanced chemical vapor deposition technique, utilizing an aerosol decomposition/vaporization process in a cold plasma reactor, was used to form YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) thin films on single-crystal MgO substrates. Aerosol droplets of the precursors were generated by an ultrasonic nebulizer operating at 1.63 MHz, while a 50 kW rf generator, operating at 2.87 MHz, was used to create the plasma and heat a stainless steel susceptor. Nitrate, acetylacetonate, and tetramethylheptanedionate compounds were used as precursors, and distilled water, ethyl alcohol, and an aqueous benzoic acid solution were investigated as solvents for the aerosol solution. The effects of the solubility and decomposition temperature of the chemical precursors, and the vapor pressure of the solvents, on the microstructure and phase assemblage of the deposits were determined. Specific combinations of substrate temperature, in the range of 800--940 C, and oxygen partial pressure, in the range of 0.3--2.7 kPa, were found to produce in situ, crystalline, stoichiometric YBCO films.