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GdxHf1-xOy. thin films were deposited by atomic layer deposition (ALD) using tris(isopropyl-cyclopentadienyl) gadolinium [Gd(PrCp)3] and HfCI4 in combination with H2O as an oxidizer. Growth curves showed a nearly ideal ALD behavior. The growth per individual Gd(iPrCp)3/H2O or HfCI4/H2O cycle was 0.55 A, independent of the Gd/(Gd + Hf) composition x in the studied range. This indicates that the amount of HfO2 deposited during a HfCI4/H2O cycle was essentially identical to the amount of Gd2O3 deposited during a Gd(iPrCp)3/H2O cycle, assuming identical atomic densities of the films independent of composition. The crystallization of GdxHf1-xOy with Gd/(Gd + Hf) contents x between 7 and 30% was studied. Films with x ⩾10% crystallized into a cubic/tetragonal HfO2-like phase during spike or laser annealing up to 1300°C, demonstrating that the cubic/tetragonal phase is thermally stable in this temperature range. A maximum dielectric constant of K∼ 36 was found for a Gd/(Gd + Hf) concentration of x 11%. [ABSTRACT FROM AUTHOR]

HighK dielectrics are intensively investigated as a replacement for SiO2 in integrated nanoelectronics. In particular, for the next generation of dynamic random access memory metalinsulatormetal capacitors, the Ta and Nbbased oxides are among the most interesting candidates that display a relatively large dielectric constant with a bandgap larger than 3 eV. In this paper, we show that it is possible to modulate the dielectric response of Ta2O5 by admixing it with Nb2O5. The dynamical charges and dielectric constants of Ta2O5 and Nb2O5 for different crystal phases were calculated at the density functional theory level. The averaged dielectric constants range between 27 (38) and 42 (77) for Ta2O5 (Nb2O5) in the hexagonal and orthorhombic varieties. A mixed orthorhombic NbTaO5 composition exhibits a directionally averaged dielectric constant of 54, close to the arithmetic mean value of the binary species. The origins of the dielectric permeability are discussed and compared to experimental measurements. [ABSTRACT FROM AUTHOR]

Ultrathin (Nb1xTax)2O5 films, with thicknesses from ∼3 to ∼ 25 nm, were deposited by chemical solution deposition starting from aqueous precursor solutions. The film's dielectric properties were characterized by capacitancevoltage and currentvoltage measurements. Permittivities ranged from 20 to 31 after annealing at 600°C, with the highest value obtained for pure Nb2O5. With increasing Nb Content, increasing leakage currents were observed. The crystallization temperature was determined by in situ Xray diffraction measurement for films with ∼15 nm thickness: Nb2O5 was crystalline as deposited (600°C), while the crystallization temperature of solid solutions increased with increasing Ta content, up to 875°C for pure Ta2O5. NbTaO5 showed a marked increase in permittivity from 27 to 38 after crystallization anneal at 600 and 800°C, respectively. For Nb2O5, no significant difference in permittivity was observed between amorphous and crystalline layers. [ABSTRACT FROM AUTHOR]

Hafnium aluminates have been investigated as highκ dielectrics for implementation in sub45 nm nonvolatile memory technologies. The growth behavior and quality of these dielectrics strongly depend on the applied deposition technique. We examine the surface reactions that occur during the atomic layer deposition (ALD) of hafnium aluminates from HfCl4, Al(CH3)3, and H2O. When grown in the ALD sequence (HfCl4/H2O)a[Al(CH3)3/H2O]5, HfCI4 chemisorption is enhanced while that of Al(CH3)3 is inhibited compared to the reaction during ALD of the respective binary oxides. Density functional theory simulations suggest that this observation is related to the more efficient hydrolysis of the AlC bond compared to HfCl. However, earlier works on ALD of HfCl4/H2O suggest that the low growth per cycle of this process is not caused by a limited hydrolysis of the HfCl bond but by dehydroxylation of the generated HfOH surface sites into less reactive Hf-O-Hf surface sites. Hence, we propose that the enhanced HfCl4 and inhibited Al(CH3)3 chemisorption during ALD of hafnium aluminates results from a difference in dehydroxy lation behavior between both binary oxides. [ABSTRACT FROM AUTHOR]