Thermal stability of Pb(C11H19O2)(2) used as the lead source in MOCVD

The thermal stability of lead bisdipivaloylmetanate [Pb(C11H19O2)(2)], used as a Pb source for the organometallic precursor in the metal-organic chemi cal vapor deposition MOCVD preparation ol Pb-based ferroelectric films, was investigated. Using thermogravimetry differential thermal analysis (TG-DTA ), with a heating rate of 10 K min(-1) and nitrogen as the carrier gas. the as-received specimen showed endothermic peaks at 132 degreesC. and complet e evaporation by 300 degreesC. Isothermal mass loss analysis showed that, i n the temperature range 100 degreesC to 200 degreesC. no degradation of the sample occurred. The specimen remained unchanged after being heated at 150 degreesC for 1800 h in a sealed vessel. On the other hand, degradation occ urred during the actual MOCVD process over 1500 h at 150 degreesC. This dec omposition was temperature: dependent as no degradation was detected under CVD operating conditions over 2400 h at 140 degreesC. Under CVD operating c onditions, at 150 degreesC, Pb(C11H19O2)(2) continuously decomposed, decomp osition products with a higher vapor pressure forming in the source contain er. Therefore, this decomposition is a characteristic feature of the MOCVD process in which the carrier gas flows through the source container.