| 1. |
- Petersson, L.-G., et al.
(författare)
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A Pd-MOS structure as a hydrogen sensor in catalytic reactions
- 1984
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Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; A2, s. 1032-
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Tidskriftsartikel (refereegranskat)abstract
- By letting a catalytic reaction involving hydrogen occur on the Pd gate metal of a Pd–MOS structure the amount of hydrogen atoms on the surface can be monitored without any external probes by measuring the dipole induced by the hydrogen atoms that have diffused to the Pd–SiO2 interface. The ability to work over a wide pressure range (10-11 Torr to atm) makes the Pd–MOS structure an interesting device in the study of catalytic reactions. In this article, we will give a short review of some of the many applications of this component. We have combined this technique with other surface sensitive techniques such as UPS, XPS, work function measurements and mass spectrometry and, e.g., studied how the hydrogen adsorption–desorption processes are influenced by alloying the Pd surface with various amounts of Ag, thereby also changing the distribution of d states close to Fermi energy. We have also studied the H2+O→H2O reaction on Pd. It, e.g., turns out that the water reaction rate reaches a maximum when the oxygen coverage approaches zero and that the hydrogen atoms on the surface have a larger lateral mobility.
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| 2. |
- Wang, Xin, et al.
(författare)
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Composition, structure, and dielectric tunability of epitaxial SrTiO3 thin films grown by radio frequency magnetron sputtering
- 1999
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Institute of Physics (AIP). - 0734-2101 .- 1520-8559. ; 17:2, s. 564-570
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial (001) oriented SrTiO3 films have been deposited on LaAlO3(001) substrates by off-axis radio frequency magnetron sputtering in Ar:O-2 gas mixtures at substrate temperatures ranging from 650 to 850 degrees C. For the deposition conditions used, stoichiometric targets yielded 20% Sr-deficient films, whereas Sr-enriched targets (Sr1.1TiO0.9O3.0) resulted in stoichiometric films. The Sr-deficient films had a mosaic structure and a larger lattice parameter in comparison to bulk SrTiO3. The stoichiometric films on the other hand had a much higher crystalline quality in the as-deposited condition. The mosaicity of the latter films was primarily limited by the crystalline quality of the LaAlO3 substrates. The lattice parameters of the stoichiometric films were also smaller than the Sr-deficient ones and closer to the bulk value. The dielectric properties of the stoichiometric films were superior to the Sr-deficient films. For films with a thickness of similar to 300 nm, the typical dielectric constants as measured at similar to 77 K and I MHz were determined to be 820 and 500, for the stoichiometric and Sr-deficient films, respectively. Also the capacitance change, as a direct current bias voltage was applied to an interdigital capacitor, was higher for the stoichiometric film, 27.3% as compared to 8.6% when applying a bias of 300 V at 77 K. We also demonstrate the effectiveness of thermal annealing in improving both crystalline quality and dielectric properties, especially for the Sr-deficient films. (C) 1999 American Vacuum Society. [S0734-2101(99)010002-7].
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| 3. |
- Achenbach, Jan-Ole, et al.
(författare)
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Low temperature oxidation behavior of Mo2BC coatings
- 2020
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : A V S AMER INST PHYSICS. - 0734-2101 .- 1520-8559. ; 38:2
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Tidskriftsartikel (refereegranskat)abstract
- Mo2BC exhibits a unique combination of high stiffness and moderate ductility, enabling the application as a protective and wear resistant coating. As the low temperature oxidation behavior of Mo2BC coatings is unexplored, direct current magnetron sputtered Mo2BC coatings were oxidized at temperatures ranging from 500 to 100 degrees C for up to 28 days. Time-of-flight elastic recoil detection analysis reveals that the onset of oxidation takes place at approximately 300 degrees C as a significant increase in the O content was observed. Crystalline oxide scales containing orthorhombic MoO3 were identified after oxidation for 15 min at 500 degrees C and 10 days at 200 degrees C. Isothermal oxidation at 200 and 100 degrees C exhibits oxide scale thicknesses of 401 +/- 33 and 22 +/- 10 nm after 14 days. Oxidation for 28 days at 100 degrees C exhibits an oxide scale thickness of 13 +/- 3 nm, which is comparable to the aforementioned oxide scale thickness after oxidation for 14 days at 100 degrees C. Based on the combination of mechanical properties and the here reported low temperature oxidation behavior, Mo2BC coatings qualify for applications in solid wood machining and low temperature forming processes at temperatures close to 100 degrees C or below.
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| 4. |
- Ahvenniemi, Esko, et al.
(författare)
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Recommended reading list of early publications on atomic layer deposition-Outcome of the "Virtual Project on the History of ALD"
- 2017
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 35:1
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Forskningsöversikt (refereegranskat)abstract
- Atomic layer deposition (ALD), a gas-phase thin film deposition technique based on repeated, self-terminating gas-solid reactions, has become the method of choice in semiconductor manufacturing and many other technological areas for depositing thin conformal inorganic material layers for various applications. ALD has been discovered and developed independently, at least twice, under different names: atomic layer epitaxy (ALE) and molecular layering. ALE, dating back to 1974 in Finland, has been commonly known as the origin of ALD, while work done since the 1960s in the Soviet Union under the name "molecular layering" (and sometimes other names) has remained much less known. The virtual project on the history of ALD (VPHA) is a volunteer-based effort with open participation, set up to make the early days of ALD more transparent. In VPHA, started in July 2013, the target is to list, read and comment on all early ALD academic and patent literature up to 1986. VPHA has resulted in two essays and several presentations at international conferences. This paper, based on a poster presentation at the 16th International Conference on Atomic Layer Deposition in Dublin, Ireland, 2016, presents a recommended reading list of early ALD publications, created collectively by the VPHA participants through voting. The list contains 22 publications from Finland, Japan, Soviet Union, United Kingdom, and United States. Up to now, a balanced overview regarding the early history of ALD has been missing; the current list is an attempt to remedy this deficiency.
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| 5. |
- Aijaz, Asim, et al.
(författare)
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Synthesis of hydrogenated diamondlike carbon thin films using neon-acetylene based high power impulse magnetron sputtering discharges
- 2016
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 34:6
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogenated diamondlike carbon (DLC:H) thin films exhibit many interesting properties that can be tailored by controlling the composition and energy of the vapor fluxes used for their synthesis. This control can be facilitated by high electron density and/or high electron temperature plasmas that allow one to effectively tune the gas and surface chemistry during film growth, as well as the degree of ionization of the film forming species. The authors have recently demonstrated by adding Ne in an Ar-C high power impulse magnetron sputtering (HiPIMS) discharge that electron temperatures can be effectively increased to substantially ionize C species [Aijaz et al., Diamond Relat. Mater. 23, 1 (2012)]. The authors also developed an Ar-C2H2 HiPIMS process in which the high electron densities provided by the HiPIMS operation mode enhance gas phase dissociation reactions enabling control of the plasma and growth chemistry [Aijaz et al., Diamond Relat. Mater. 44, 117 (2014)]. Seeking to further enhance electron temperature and thereby promote electron impact induced interactions, control plasma chemical reaction pathways, and tune the resulting film properties, in this work, the authors synthesize DLC: H thin films by admixing Ne in a HiPIMS based Ar/C2H2 discharge. The authors investigate the plasma properties and discharge characteristics by measuring electron energy distributions as well as by studying discharge current characteristics showing an electron temperature enhancement in C2H2 based discharges and the role of ionic contribution to the film growth. These discharge conditions allow for the growth of thick (>1 mu m) DLC: H thin films exhibiting low compressive stresses (similar to 0.5 GPa), high hardness (similar to 25 GPa), low H content (similar to 11%), and density in the order of 2.2 g/cm(3). The authors also show that film densification and change of mechanical properties are related to H removal by ion bombardment rather than subplantation.
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| 6. |
- Alami, Jones, et al.
(författare)
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Ion-assisted Physical Vapor Deposition for enhanced film properties on non-flat surfaces
- 2005
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 23:2, s. 278-280
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Tidskriftsartikel (refereegranskat)abstract
- We have synthesized Ta thin films on Si substrates placed along a wall of a 2-cm-deep and 1-cm-wide trench, using both a mostly neutral Ta flux by conventional dc magnetron sputtering (dcMS) and a mostly ionized Ta flux by high-power pulsed magnetron sputtering (HPPMS). Structure of the grown films was evaluated by scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. The Ta thin film grown by HPPMS has a smooth surface and a dense crystalline structure with grains oriented perpendicular to the substrate surface, whereas the film grown by dcMS exhibits a rough surface, pores between the grains, and an inclined columnar structure. The improved homogeneity achieved by HPPMS is a direct consequence of the high ion fraction of sputtered species.
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| 7. |
- Aleman, Angel, et al.
(författare)
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Ultrahigh vacuum dc magnetron sputter-deposition of epitaxial Pd(111)/Al2O3(0001) thin films
- 2018
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Ingår i: Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 36:3
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Tidskriftsartikel (refereegranskat)abstract
- Pd(111) thin films, ∼245 nm thick, are deposited on Al2O3(0001) substrates at ≈0.5Tm, where Tm is the Pd melting point, by ultrahigh vacuum dc magnetron sputtering of Pd target in pure Ar discharges. Auger electron spectra and low-energy electron diffraction patterns acquired in situ from the as-deposited samples reveal that the surfaces are compositionally pure 111-oriented Pd. Double-axis x-ray diffraction (XRD) ω-2θ scans show only the set of Pd 111 peaks from the film. In triple-axis high-resolution XRD, the full width at half maximum intensity Γω of the Pd 111 ω-rocking curve is 630 arc sec. XRD 111 pole figure obtained from the sample revealed six peaks 60°-apart at a tilt angles corresponding to Pd 111 reflections. XRD φ scans show six 60°-rotated 111 peaks of Pd at the same φ angles for 11 23 of Al2O3 based on which the epitaxial crystallographic relationships between the film and the substrate are determined as (111)Pd∥ (0001)Al2O3 with two in-plane orientations of [112]Pd∥ [1120]Al2O3 and [211]Pd∥ [1120]Al2O3. Using triple axis symmetric and asymmetric reciprocal space maps, interplanar spacings of out-of-plane (111) and in-plane (11 2) are found to be 0.2242 ± 0.0003 and 0.1591 ± 0.0003 nm, respectively. These values are 0.18% lower than 0.2246 nm for (111) and the same, within the measurement uncertainties, as 0.1588 nm for (11 2) calculated from the bulk Pd lattice parameter, suggesting a small out-of-plane compressive strain and an in-plane tensile strain related to the thermal strain upon cooling the sample from the deposition temperature to room temperature. High-resolution cross-sectional transmission electron microscopy coupled with energy dispersive x-ray spectra obtained from the Pd(111)/Al2O3(0001) samples indicate that the Pd-Al2O3 interfaces are essentially atomically abrupt and dislocation-free. These results demonstrate the growth of epitaxial Pd thin films with (111) out-of-plane orientation with low mosaicity on Al2O3(0001).
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| 8. |
- Alijan Farzad Lahiji, Faezeh, et al.
(författare)
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Growth and optical properties of NiO thin films deposited by pulsed dc reactive magnetron sputtering
- 2023
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : A V S AMER INST PHYSICS. - 0734-2101 .- 1520-8559. ; 41:6
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Tidskriftsartikel (refereegranskat)abstract
- NiO thin films with varied oxygen contents are grown on Si(100) and c-Al2O3 at a substrate temperature of 300 degrees C using pulsed dc reactive magnetron sputtering. We characterize the structure and optical properties of NiO changes as functions of the oxygen content. NiO with the cubic structure, single phase, and predominant orientation along (111) is found on both substrates. X-ray diffraction and pole figure analysis further show that NiO on the Si(100) substrate exhibits fiber-textured growth, while twin domain epitaxy was achieved on c-Al2O3, with NiO(111) k Al2O3(0001) and NiO[1 (1) over bar0]k Al2O3[10 (1) over bar0] or NiO[(1) over bar 10]k Al2O3[2 (1) over bar(1) over bar0] epitaxial relationship. The oxygen content in NiO films did not have a significant effect on the refractive index, extinction coefficient, and absorption coefficient. This suggests that the optical properties of NiO films remained unaffected by changes in the oxygen content.
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| 9. |
- Alling, Björn, et al.
(författare)
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Theoretical investigation of cubic B1-like and corundum (Cr1−xAlx)2O3 solid solutions
- 2013
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 31:3
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Tidskriftsartikel (refereegranskat)abstract
- First-principles calculations are employed to investigate the stability and properties of cubic rock-salt-like (Cr1−xAlx)2O3 solid solutions, stabilized by metal site vacancies as recently reported experimentally. It is demonstrated that the metal site vacancies can indeed be ordered in a way that gives rise to a suitable fourfold coordination of all O atoms in the lattice. B1-like structures with ordered and disordered metal site vacancies are studied for (Cr0.5Al0.5)2O3 and found to have a cubic lattice spacing close to the values reported experimentally, in contrast to fluorite-like and perovskite structures. The obtained B1-like structures are higher in energy than corundum solid solutions for all compositions, but with an energy offset per atom similar to other metastable systems possible to synthesize with physical vapor deposition techniques. The obtained electronic structures show that the B1-like systems are semiconducting although with smaller band gaps than the corundum structure.
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| 10. |
- Almer, Jonathan, et al.
(författare)
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Microstructural evolution during tempering of arc-evaporated Cr-N coatings
- 2000
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 18:1, s. 121-130
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Tidskriftsartikel (refereegranskat)abstract
- Cr-N coatings were arc-deposited at 50 and 300 V. The changes in the coating microstructure and phase content during tempering were monitored. As a result, the phase stability and activation energies for defect diffusion were determined as a function of ion energy.
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