Deposition of ferroelectric oxides by MOCVD

There is a growing interest in the deposition of thin film complex oxides such as superconducting, electro-optic and ferroelectric compounds. A number of techniques are suitable for depositing these films, each having advantages and disadvantages. This paper describes the use of metal organic chemical vapour deposition (MOCVD) for the preparation of ferroelectric lead scandium tantalate. Because of the low volatility of the precursurs used the deposition is performed in a low pressure horizontal reactor. The precursors are individually transported into a mixing rail, then to the reaction site ising helium. The depositions have been performed at temperatures of 650°-850°C, resulting in perovskite films with a grain size of 0.1-1 μm. The deposition rate can be varied between 0.5-10 μm/h depending on bubbler temperature and gas flows, however, good film quality is only obtained at 0.5-2 μm/h. The relationship between film morphology growth conditions and electrical performance of the films is discussed.