EXPERIMENT AND MODELING ON THE EVAPORATION OF BETA-DIKETONATES OF COPPER, YTTRIUM AND BARIUM

The evaporation behavior of the beta-diketonates of copper, yttrium an d barium were investigated in detail. The effects of sample characteri stics and operating conditions, such as carrier gas flow rate, system pressure and temperature, and exposure area were studied. An empirical correlation, n = k2 L2/3P-1Q1/9 exp(-DELTAH/RT), which is based on a simple mass transfer model is proposed to describe the rate of evapora tion for these beta-diketonates. The L2/3 term represents the effects of the exposure area of the organometallic sample. The calculated valu es agree well with our experimental data. The evaporation rate is, in general, very sensitive to temperature and system pressure, but not to gas flow rate. Another factor that influences the reproducibility of the evaporation is the stability of the material during storage. Stori ng the precursors below -10-degrees-C seems to help.