SURFACE-MORPHOLOGY STUDIES OF Y-BA-CU-OXIDE THIN-FILMS PREPARED BY PULSED ORGANOMETALLIC BEAM EPITAXY

Pulsed organometallic beam epitaxy is a new technique for the depositi on of complex metal oxide films. With this technique each metal precur sor species is sequentially pulsed onto the substrate. The flux of the precursor is monitored and computer feedback control is used to adjus t the size of each precursor pulse, allowing precise control of the me tal stoichiometry. Smooth films of YBa2CU3O7-delta, as examined by SEM , can be made with this technique in a temperature range that includes 640-680-degrees-C using the beta-diketonate precursors, Y(dipivalolym ethanate)3, Ba(hexafluoroacetylacetonate)2.tetraglyme, and Cu(acetylac etonate)2. The morphology of the films is dependent on the ratio of th e three precursors delivered to the substrate. The ratio of the three precursors must be held to better than +/-10% in order to produce smoo th films. The ratio between the three precursors needed to produce a s mooth film changes with the deposition temperature. The relative amoun t of yttrium precursor delivered to the substrate must be decreased as the temperature is increased in order to maintain a smooth film. The metal composition of the smooth films is Y1Ba2CU3 (+/-4%).