| 1. |
- Jogi, Indrek, et al.
(författare)
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Investigation of ZrO2-Gd2O3 Based High-k Materials as Capacitor Dielectrics
- 2010
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 157:10, s. G202-G210
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Tidskriftsartikel (refereegranskat)abstract
- Atomic layer deposition (ALD) of ZrO2-Gd2O3 nanolaminates and mixtures was investigated for the preparation of a high permittivity dielectric material. Variation in the relative number of ALD cycles for constituent oxides allowed one to obtain films with controlled composition. Pure ZrO2 films possessed monoclinic and higher permittivity cubic or tetragonal phases, whereas the inclusion of Gd2O3 resulted in the disappearance of the monoclinic phase. Changes in phase composition were accompanied with increased permittivity of mixtures and laminates with low Gd content. Further increase in the lower permittivity Gd2O3 content above 3.4 cat. % resulted in the decreased permittivity of the mixtures. Leakage currents generally decreased with increasing Gd content, whereby laminated structures demonstrated smaller leakage currents than mixed films at a comparable Gd content. Concerning the bottom electrode materials, the best results in terms of permittivity and leakage currents were achieved with Ru, allowing a capacitance equivalent oxide thickness of similar to 1 nm and a current density of 3 X 10(-8) A/cm(2) at 1 V. Charge storage values up to 60 nC/mm(2) were obtained for mixtures and laminates with thickness below 30 nm. In general, at electric fields below 2-3 MV/cm, normal and trap-compensated Poole-Frenkel conduction mechanisms were competing, whereas at higher fields, Fowler-Nordheim and/or trap-assisted tunneling started to dominate.
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| 2. |
- Kukli, Kaupo, et al.
(författare)
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Atomic layer deposition of Ru films from bis(2,5-dimethylpyrrolyl)ruthenium and oxygen
- 2012
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 520:7, s. 2756-2763
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Tidskriftsartikel (refereegranskat)abstract
- Ru thin films were grown on hydrogen terminated Si, SiO2, Al2O3, HfO2, and TiO2 surfaces by atomic layer deposition from bis(2,5-dimethylpyrrolyl)ruthenium precursor and oxygen. The 4-20 nm thick films on these surfaces consisted of nanocrystalline hexagonal metallic ruthenium, regardless of the deposition temperature. At the lowest temperatures examined, 250-255 degrees C, the growth of the Ru films was favored on silicon, compared to the growth on Al2O3, TiO2 and HfO2. At higher temperatures the nucleation and growth of Ru became enhanced in particular on HfO2, compared to the process on silicon. At 320-325 degrees C, no growth occurred on Si-H and SiO2-covered silicon. Resistivity values down to 18 mu Omega.cm were obtained for ca. 10 nm thick Ru films.
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| 3. |
- Vockenhuber, Christof, et al.
(författare)
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Energy-loss straggling of 2–10 MeV/u Kr ions in gases
- 2013
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Ingår i: European Physical Journal D. - : EDP Sciences: EPJ. - 1434-6060 .- 1434-6079. ; 67:7
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Tidskriftsartikel (refereegranskat)abstract
- Measurements have been performed on a time-of-flight setup at the Jyväskylä K130 cyclotron, aiming at energy-loss straggling of heavy ions in gases. Theoretical predictions based on recently developed theory as well as an empirical interpolation formula predict that straggling can be more than ten times higher than Bohr straggling in the MeV/u regime. Our measurements with up to 9.3 MeV/u Kr ions on He, N2, Ne and Kr targets confirm this feature. Our calculations show the relative contributions of linear straggling, bunching including packing, and charge exchange. Our results for stopping cross sections are compatible with values from the literature.
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