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| Hauptseite > Publikationsdatenbank > Rare earth scandate thin films by atomic layer deposition: effect of the rare earth cation size |
| Hauptseite > Publikationsdatenbank > Rare earth scandate thin films by atomic layer deposition: effect of the rare earth cation size |
| Journal Article | PreJuSER-10419 |
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2010
ChemSoc
London
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Please use a persistent id in citations: doi:10.1039/c0jm00363h
Abstract: A series of amorphous REScO3 films was deposited by atomic layer deposition (ALD) using rare earth (RE) beta-diketonate precursors RE(thd)(3) (thd = 2,2,6,6-tetramethyl-3,5-heptanedionato) together with ozone in an attempt to study the effect of the RE3+ cation size on various film properties. A clear correlation between the deposition rate and the RE3+ cation radius was established. REScO3 films with a metal ratio RE : Sc =1, close to the stoichiometric one, viz. RE : Sc 1, and a small excess of oxygen were realized by adjusting the metal precursor pulsing ratio. Small amount of carbon was found as impurity in all the films, concentrations varying from 1-3 at% (RE = La, Gd or Dy) to 0.4-0.5 at% (RE = Er or Lu). Also the crystallization temperature and the resulting phase were affected by the RE3+ cation size. The REScO3 films were found to crystallize either as an orthorhombic perovskite phase or as a solid solution of the cubic C-type oxides. High crystallization temperatures of 800-900 degrees C were observed for LaScO3, GdScO3 and DyScO3. All the films gave smooth C-V curves with very small hysteresis (typically < 35 mV). The highest dielectric constant (kappa approximate to 24) was found for DyScO3. Also the leakage current densities were small, typically in a range of 10(-6)-10(-9) A cm(-2) at 1 V. The results confirm that REScO3 films deposited by ALD are potential candidates for new generation high-kappa gate dielectrics.
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