Ta2O5-based high-K dielectric thin films from solution processed at low temperatures

• Ta2O5–Al2O3–SiO2 (Ta:Al:Si = 8:1:1 atomic ratio) and Ta2O5 films were processed from solutions.
• The XRD-amorphous films, heated at or below 400 °C, are smooth (RMS < 0.5 nm).
• The dielectric permittivity of the single- and mixed-oxide films heated at 400 °C is 27 and 22, respectively.
• The current–voltage characteristics of the mixed-oxide films reveal the Poole–Frenkel behaviour.

Ta2O5-based thin films were prepared by chemical solution deposition at temperatures not exceeding 400 °C. The aim of the work was to investigate the properties of high-K dielectric films of the ternary composition Ta2O5–Al2O3–SiO2 with the Ta:Al:Si = 8:1:1 atomic ratio. Pure Ta2O5 samples were also prepared. All thin films were amorphous, and had smooth and flat surfaces with the average roughness of below 0.5 nm. The mixed oxide samples heated between 300 °C and 400 °C showed little difference in the dielectric permittivity with the values ranging from about 19 to 22. The Ta2O5 film heated at 400 °C exhibited the highest permittivity of about 27. The current–voltage measurements revealed considerably improved characteristics of the Ta2O5–Al2O3–SiO2 samples within the investigated heating temperature range, with a significant overall decrease of the leakage currents in contrast to that of the pure Ta2O5 thin films.

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