RAMAN AND INFRARED-SPECTROSCOPY AND TRANSPORT-PROPERTIES OF AGED ORGANOMETALLIC PRECURSORS USED FOR THE DEPOSITION OF HIGH-T-C SUPERCONDUCTING FILMS

Raman and infrared (IR) spectra of Ba, Sr and Ca 2,2,6,6-tetramethyl-3 ,5-heptanedionates (THD), volatile precursors used for organometallic chemical vapor deposition (OMCVD) of high-T-c superconducting (HTCS) t hin films, have been studied for freshly supplied commercial materials or those prepared in our laboratory and aged for several months in va cuum and in air. Some of the spectral lines present in freshly prepare d material disappeared in precursors aged in air but were unchanged if aged in vacuum. Only freshly prepared or vacuum-stored Ba(THD)(2) cou ld be 100% transported by sublimating at 210 degrees C. Air aged mater ial transported only 60% under the same conditions of evaporation. Mix ing 20% aged Ba(THD)(2) with 80% naphthalene achieved 100% transport o f Ba(THD)(2).