Combustion Chemical Vapor Deposition from Liquid Organic Solutions

A novel chemical vapor deposition technique using a flame, combustion chemical vapor deposition (CCVD), was conceptualized and experimentally tested. Organic liquid solutions containing film precursors were atomized and combusted, thus forming the flame. The CCVD experiments were performed in the open atmosphere, and resulted in the deposition of dense, uniform, specular, heterogeneously nucleated thin films. The deposition of the coatings occurred onto substrates located at or near the tip of the flame, such that the substrate was heated sufficiently without any additional heat source being used. Initially numerous materials were deposited to test the capability of CCVD to deposit different materials. Heterogeneously nucleated thin films of YBa_2Cu _3O_{rm x}, YSZ, Y_2BaCuO _{rm x}, BaTiO_3 , YIG, Ag, Pt and SiO_2 were all successfully deposited on the first attempt. A series of deposition studies were then performed to test aspects of the original hypothesis. These studies showed that CCVD using combustible solutions has good compositional control; that film uniformity and smoothness was optimized at oblique angles to the flame; that the substrate should be located in or near the flame's end; that if solution concentrations are too high the coating becomes particulate (homogeneously nucleated); that depositing onto substrates that oxidize in air is difficult; that gravity does not have a distinguishable effect; that for YSZ and the apparatus used the maximum practical thickness of the film was about 2.5 mum; and that larger area coatings can be deposited by moving the substrate through the flame. The original hypothesis was then expanded and slightly altered in light of the experimental results.