Characterization and electrical properties of high-k GdScO3 thin films grown by atomic layer deposition
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- Myllymäki, P., Roeckerath, M., Putkonen, M. et al. Appl. Phys. A (2007) 88: 633. doi:10.1007/s00339-007-4069-7
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Gadolinium scandium oxide (Gd-scandate, GdScO3) thin films were grown by atomic layer deposition (ALD) from β-diketonate precursors M(thd)3 (M=Gd, Sc; thd=2,2,6,6-tetramethyl-3,5-heptanedionato) and ozone. The deposition parameters were optimized to produce films with the stoichiometric 1:1 metal ratio and a series of samples with nominal thicknesses of 5, 10, 15, and 20 nm were prepared. At 300 °C the metal precursor pulsing ratio Gd:Sc=5:6 yielded amorphous stoichiometric films and a growth rate of 0.21 Å/cycle. The films stayed amorphous up to 900 °C. The surface was probed with an AFM and the rms roughness was found to be 0.3 nm for the 5–20 nm thick films. The electrical properties of the as-deposited films proved to be very promising, with a dielectric constant of ∼22 and leakage current density of 340 μA/cm2, measured at -2 V.