Low-temperature processing and properties of solution derived tantalum oxide-based thin films

Tantalum pentoxide (Ta2O5) thin films are of high interest due to their possible applications in the field of microelectronics and integrated microtechnologies. Furthermore, one main requirement for transparent electronics is the deposition onto substrates requiring low temperature processing, as glass or even plastic. Ta2O5-based thin films were deposited by Chemical Solution Deposition (CSD). Precursor solutions were prepared by dissolution of metal alkoxides in organic solvents, adjusting the reactivity of the metal by the use of suitable additives. The films have single and ternary mixed compositions of Ta2O5, without and respectively with Al2O3 and SiO2. The Ta2O5-based films were prepared by spin coating the precursor solutions onto platinized silicon and glass substrates. In order to investigate the effect of composition and thermal treatment upon their properties, the as-prepared films were heated in the range of temperature: 250oC - 400oC. The samples were characterized from the structural, optical and electrical point of view. Regardless their composition and the substrate used, the films are amorphous and show very flat surfaces. For the Ta2O5-based thin films the permittivity increases with the heating temperature. The Ta2O5 film heated at 400oC exhibits the highest value of the dielectric permittivity. Optical transmittance of all studied films increases with the addition of both Al and Si oxides.