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Lu, Jun
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Jogi, I., Kukli, K., Ritala, M., Leskela, M., Aarik, J., Aidla, A. & Lu, J. (2010). Atomic layer deposition of high capacitance density Ta2O5-ZrO2 based dielectrics for metal-insulator-metal structures. Microelectronic Engineering, 87(2), 144-149
Open this publication in new window or tab >>Atomic layer deposition of high capacitance density Ta2O5-ZrO2 based dielectrics for metal-insulator-metal structures
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2010 (English)In: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 87, no 2, p. 144-149Article in journal (Refereed) Published
Abstract [en]

We have investigated electrical properties of laminated atomic layer deposited films: ZrO2-Ta2O5, ZrO2-Nb2O5-Ta2O5, ZrO2-TaxNb1-xO5 and Ta2O5-ZrxNbyOz. Even though the capacitances of laminates were often higher compared to films of constituent materials with similar thickness, considerably higher charge storage factors, Q were achieved only when tetragonal ZrO2 was stabilized in ZrO2-Ta2O5 laminate and when the laminate thickness exceeded 50 rim. The decreased Q values in the case of most laminates were the result of increased leakage currents. In the case of thinner films only Ta2O5-ZrxNbyOz, stack possessed capacitance density and Q value higher than reference HfO2. Concerning the conduction mechanisms, in the case of thinner films, the Ta2O5 or TaxNb1-xO5 apparently controlled the leakage either by Richardson-Schottky emission or Poole-Frenkel effect. (C) 2009 Elsevier B.V. All rights reserved

Keywords
Nanolaminates, Atomic layer deposition, High-k dielectric
National Category
Engineering and Technology Natural Sciences
Identifiers
urn:nbn:se:uu:diva-137943 (URN)10.1016/j.mee.2009.06.032 (DOI)000273292700011 ()
Available from: 2010-12-16 Created: 2010-12-16 Last updated: 2018-06-01Bibliographically approved
Jogi, I., Tamm, A., Kukli, K., Kemell, M., Lu, J., Sajavaara, T., . . . Leskelä, M. (2010). Investigation of ZrO2-Gd2O3 Based High-k Materials as Capacitor Dielectrics. Journal of the Electrochemical Society, 157(10), G202-G210
Open this publication in new window or tab >>Investigation of ZrO2-Gd2O3 Based High-k Materials as Capacitor Dielectrics
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2010 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 157, no 10, p. G202-G210Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-135179 (URN)10.1149/1.3478117 (DOI)000281306900065 ()
Available from: 2010-12-06 Created: 2010-12-06 Last updated: 2017-12-12Bibliographically approved
Li, L.-G., Vallin, Ö., Lu, J., Smith, U., Norström, H. & Olsson, J. (2010). Oxygen out-diffusion from buried layers in SOI and SiC-SOI substrates. Solid-State Electronics, 54(2), 153-157
Open this publication in new window or tab >>Oxygen out-diffusion from buried layers in SOI and SiC-SOI substrates
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2010 (English)In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 54, no 2, p. 153-157Article in journal (Refereed) Published
Abstract [en]

We have made a comparative study of the oxygen out-diffusion process during heat treatment of SOI wafers and SiC-SOI hybrid substrates. SOI materials with three different thicknesses (2, 20 and 410 nm) of buried oxide (BOX) were used in the investigation High-resolution cross-sectional transmission electron microscopy (HRXTEM) together with laser interferometry was used to determine the remaining thickness of the BOX-layer after heat treatment. After complete removal of the BOX-layer of SOI wafers, the St/Si interface appears to be sharp and defect-free. Similar results were obtained for SiC-SOI hybrid substrates after removal of the entire buried oxide layer. For all combinations investigated oxide removal was accompanied by a thickness reduction and roughening of the silicon surface layer as verified by atomic force microscopy (AFM).

Keywords
Oxygen out-diffusion, SOI, silicon carbide, SiC-SOI
National Category
Condensed Matter Physics Engineering and Technology
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-117563 (URN)10.1016/j.sse.2009.12.011 (DOI)000275691400012 ()
Available from: 2012-08-23 Created: 2010-02-19 Last updated: 2017-12-12Bibliographically approved
Kukli, K., Aarik, J., Aidla, A., Uustare, T., Jogi, I., Lu, J., . . . Leskela, M. (2010). Structure and morphology of Ru films grown by atomic layer deposition from 1-ethyl-1 '-methyl-ruthenocene. Journal of Crystal Growth, 312(12-13), 2025-2032
Open this publication in new window or tab >>Structure and morphology of Ru films grown by atomic layer deposition from 1-ethyl-1 '-methyl-ruthenocene
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2010 (English)In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 312, no 12-13, p. 2025-2032Article in journal (Refereed) Published
Abstract [en]

Ru thin films were grown on TiO2, Al2O3, HfO2, and ZrO2 films as well as on HF-etched silicon and SiO2-covered silicon by atomic layer deposition from 1-ethyl-1'-methyl-ruthenocene, (CH3C5H4) (C2H5C5H4)Ru, and oxygen. The growth of Ru was obtained and characterized at temperatures ranging from 250 to 325 degrees C. On epitaxial rutile, highly oriented growth of Ru with hexagonal structure was achieved, while on other substrates the films possessed nonoriented hexagonal structure. Ruthenium oxide was not detected in the films. The lowest resistivity value obtained for 5.0-6.6 nm thick films was 26 mu Omega cm. The conductivity of the films depended somewhat on the deposition cycle time parameters and, expectedly, more strongly on the amount of deposition cycles. Increase in the deposition temperature of underlying metal oxide films increased the conductivity of Ru layers.

Keywords
Crystal morphology, Substrates, Roughening, Chemical vapor deposition processes, Atomic layer epitaxy, Polycrystalline deposition
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-135556 (URN)10.1016/j.jcrysgro.2010.03.033 (DOI)000278477900023 ()
Available from: 2010-12-14 Created: 2010-12-07 Last updated: 2017-12-11Bibliographically approved
Lindahl, E., Lu, J., Ottosson, M. & Carlsson, J.-O. (2009). Epitaxial NiO(100) and NiO(111) films grown by atomic layer deposition. Journal of Crystal Growth, 311(16), 4082-4088
Open this publication in new window or tab >>Epitaxial NiO(100) and NiO(111) films grown by atomic layer deposition
2009 (English)In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 311, no 16, p. 4082-4088Article in journal (Refereed) Published
Abstract [en]

Epitaxial NiO (1 1 1) and NiO (1 0 0) films have been grown by atomic   layer deposition on both MgO (1 0 0) and alpha-Al2O3 (0 0 1) substrates   at temperatures as low as 200 degrees C by using   bis(2,2,6,6-tetramethyl-3,5-heptanedionato)Ni(II) and water as   precursors. The films grown on the MgO (1 0 0) substrate show the   expected cube on cube growth while the NiO (1 1 1) films grow with a   twin rotated 180 degrees on the alpha-Al2O3 (0 0 1) substrate surface.   The films had columnar microstructures on both substrate types. The   single grains were running throughout the whole film thickness and were   significantly smaller in the direction parallel to the surface. Thin   NiO (1 1 1) films can be grown with high crystal quality with a FWHM of   0.02-0.05 degrees in the rocking curve measurements.

Place, publisher, year, edition, pages
Elsevier, 2009
Keywords
Atomic layer deposition, X-ray diffraction, Transmission electron microscopy, NiO (100), NiO (111), Crystallite size
National Category
Chemical Sciences Engineering and Technology
Research subject
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-111450 (URN)10.1016/j.jcrysgro.2009.06.030 (DOI)000269580100018 ()
Available from: 2009-12-15 Created: 2009-12-15 Last updated: 2017-12-12Bibliographically approved
Gudmundsson, V., Hellström, P.-E., Luo, J., Lu, J., Zhang, S.-L. & Östling, M. (2009). Fully Depleted UTB and Trigate N-Channel MOSFETs Featuring Low-Temperature PtSi Schottky-Barrier Contacts With Dopant Segregation. IEEE Electron Device Letters, 30(5), 541-543
Open this publication in new window or tab >>Fully Depleted UTB and Trigate N-Channel MOSFETs Featuring Low-Temperature PtSi Schottky-Barrier Contacts With Dopant Segregation
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2009 (English)In: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 30, no 5, p. 541-543Article in journal (Refereed) Published
Abstract [en]

Schottky-barrier source/drain (SB-S/D) presents a promising solution to reducing parasitic resistance for device architectures such as fully depleted UTB, trigate, or FinFET. In this letter, a low-temperature process (<= 700 degrees C) with PtSi-based S/D is examined for the fabrication of n-type UTB and trigate FETs on SOI substrate (t(si) = 30 nm). Dopant segregation with As was used to achieve the n-type behavior at implantation doses of 1 (.) 10(15) and 5. 10(15) cm(-2). Similar results were found for UTB devices with both doses, but trigate devices with the larger dose exhibited higher on currents and smaller process variation than their lower dose counterparts.

Keywords
Dopant segregation (DS), FinFET, platinum silicide PtSi, Schottky-barrier (SB)-MOSFET, trigate
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-129092 (URN)10.1109/LED.2009.2015900 (DOI)000265711700039 ()
Available from: 2010-08-06 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
Santala, E., Hamalainen, J., Lu, J., Leskela, M. & Ritala, M. (2009). Metallic Ir, IrO2 and Pt Nanotubes and Fibers by Electrospinning and Atomic Layer Deposition. Nanoscience and Nanotechnology Letters, 1(3), 218-223
Open this publication in new window or tab >>Metallic Ir, IrO2 and Pt Nanotubes and Fibers by Electrospinning and Atomic Layer Deposition
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2009 (English)In: Nanoscience and Nanotechnology Letters, ISSN 1941-4900, E-ISSN 1941-4919, Vol. 1, no 3, p. 218-223Article in journal (Refereed) Published
Abstract [en]

One-dimensional iridium and iridium oxide fibers were prepared by electrospinning of polyvinyl pyrrolidone ethanol solution which contained iridium(III) acetylacetonate as iridium precursor. The Ir precursors/polymer composite fibers were subsequently thermally annealed at 500 degrees C in air for 4 hours to remove the organic parts and leave IrO2 fibers. Metallic iridium fibers were obtained by reducing the IrO2 fibers with hydrogen. Also tubes by fiber templates-process is used to demonstrate how metallic Ir, IrO2 and Pt nanotubes can be produced by combining atomic layer deposition and electrospinning.

Keywords
Electrospinning, Atomic Layer Deposition, Noble Metal Fiber, Noble Metal Tube, TUFT Process
National Category
Nano Technology
Identifiers
urn:nbn:se:uu:diva-260076 (URN)10.1166/nnl.2009.1042 (DOI)000208013800015 ()
Available from: 2015-08-14 Created: 2015-08-14 Last updated: 2017-12-04Bibliographically approved
Cheah, S. K., Perre, E., Rooth, M., Fondell, M., Hårsta, A., Nyholm, L., . . . Edström, K. (2009). Self-Supported Three-Dimensional Nanoelectrodes for Microbattery Applications. Nano letters (Print), 9(9), 3230-3233
Open this publication in new window or tab >>Self-Supported Three-Dimensional Nanoelectrodes for Microbattery Applications
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2009 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 9, no 9, p. 3230-3233Article in journal (Refereed) Published
Abstract [en]

A nanostructured three-dimensional (3D) microbattery has been produced and cycled in a Li-ion battery. It consists of a current collector of aluminum nanorods, a uniform layer of 17 nm TiO2 covering the nanorods made using ALD, an electrolyte and metallic lithium counter electrode. The battery is electrochemically cycled more than 50 times. The increase in total capacity is 10 times when using a 3D architechture compared to a 2D system for the same footprint area.

Place, publisher, year, edition, pages
American Chemical Society, 2009
National Category
Chemical Sciences Engineering and Technology
Research subject
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-119450 (URN)10.1021/nl9014843 (DOI)000269654900025 ()
Available from: 2010-02-25 Created: 2010-02-25 Last updated: 2017-12-30
Soroka, I., Rooth, M., Lu, J., Boman, M., Svedlindh, P., Carlsson, J.-O. & Hårsta, A. (2009). Template-based multiwalled TiO2/iron oxides nanotubes:: Structure and magnetic properties. Journal of Applied Physics, 106(8), 084313
Open this publication in new window or tab >>Template-based multiwalled TiO2/iron oxides nanotubes:: Structure and magnetic properties
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2009 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 106, no 8, p. 084313-Article in journal (Refereed) Published
Abstract [en]

Double-and triple-walled TiO2/iron oxide nanotubes with well defined interfaces havebeen produced in nanoporous alumina templates using atomic layer depositionmethod. The structural properties of each individual layer are foundto be dependent on the deposition temperatures. The outer layersof TiO2 are polycrystalline and consist of a phase mixtureof anatase and rutile, while the inner TiO2 layers grownat lower temperature are amorphous. The iron oxide layers consistof pure hematite when deposited at 500 °C, while a phasemixture of hematite and magnetite was obtained at 400 °C. Themagnetization measurements reveal that the studied nanotubes exhibit weak ferromagneticbehavior and magnetic anisotropy with an easy axis perpendicular tothe tube axis.

Place, publisher, year, edition, pages
American Institute of Physics, 2009
National Category
Chemical Sciences Engineering and Technology
Research subject
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-119918 (URN)10.1063/1.3245395 (DOI)000271358100088 ()
Available from: 2010-03-03 Created: 2010-03-03 Last updated: 2017-12-12Bibliographically approved
Niinisto, J., Kukli, K., Tamm, A., Putkonen, M., Dezelah, C. L., Niinisto, L., . . . Leskela, M. (2008). Advanced cyclopentadienyl precursors for atomic layer deposition of ZrO2 thin films. Journal of Materials Chemistry, 18(28), 3385-3390
Open this publication in new window or tab >>Advanced cyclopentadienyl precursors for atomic layer deposition of ZrO2 thin films
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2008 (English)In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 18, no 28, p. 3385-3390Article in journal (Refereed) Published
Abstract [en]

ZrO2 thin films were grown onto silicon (100) substrates by atomic layer deposition (ALD) using novel cyclopentadienyl-type precursors, namely (CpMe)(2)ZrMe2 and (CpMe)(2)Zr(OMe) Me (Cp = cyclopentadienyl, C5H5) together with ozone as the oxygen source. Growth characteristics were studied in the temperature range of 250 to 500 degrees C. An ALD-type self-limiting growth mode was verified for both processes at 350 degrees C where highly conformal films were deposited onto high aspect ratio trenches. Signs of thermal decomposition were not observed at or below 400 degrees C, a temperature considerably exceeding the thermal decomposition temperature of the Zr-alkylamides. Processing parameters were optimised at 350 degrees C, where deposition rates of 0.55 and 0.65 angstrom cycle(-1) were obtained for (CpMe)(2)ZrMe2/O-3 and (CpMe)(2)Zr(OMe)Me/O-3, respectively. The films grown from both precursors were stoichiometric and polycrystalline with an increasing contribution from the metastable cubic phase with decreasing film thickness. In the films grown from (CpMe)(2)ZrMe2, the breakdown field did not essentially depend on the film thickness, whereas in the films grown from (CpMe)(2)Zr(OMe)Me the structural homogeneity and breakdown field increased with decreasing film thickness. The films exhibited good capacitive properties that were characteristic of insulating oxides and did not essentially depend on the precursor chemistry.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-109985 (URN)10.1039/b802523a (DOI)000257509700016 ()
Available from: 2009-11-02 Created: 2009-11-02 Last updated: 2018-06-01Bibliographically approved
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