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Atomic layer deposited iridium oxide thin film as microelectrode coating in stem cell applications

Tomi Ryynänen, Laura Ylä-Outinen, Susanna Narkilahti, Jarno M. A. Tanskanen, Jari Hyttinen, Jani Hämäläinen, Markku Leskelä, and Jukka Lekkala

J. Vac. Sci. Technol. A 30, 041501 (2012); http://dx.doi.org/10.1116/1.4709447 (5 pages)

Online Publication Date: 27 April 2012

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Microelectrodes of microelectrode arrays (MEAs) used in cellular electrophysiology studies were coated with iridium oxide (IrOx) thin film using atomic layer deposition (ALD). This work was motivated by the need to find a practical alternative to commercially used titanium nitride (TiN) microelectrode coating. The advantages of ALD IrOx coating include decreased impedance and noise levels and improved stimulation capability of the microelectrodes compared to uncoated microelectrodes. The authors’ process also takes advantage of ALD’s exact process control and relatively low source material start costs compared to traditionally used sputtering and electrochemical methods. Biocompatibility and suitability of ALD IrOx microelectrodes for stem cell research applications were verified by culturing human embryonic stem cell derived neuronal cells for 28 days on ALD IrOx MEAs and successfully measuring electrical activity of the cell network. Electrode impedance of 450 kΩ at 1 kHz was achieved with ALD IrOx in the authors’ 30 μm microelectrodes. This is better than that reported for any uncoated microelectrodes with equal size, even equal to that of inactivated sputtered IrOx coating. Also, stimulation capability was demonstrated. However, further development, including, e.g., applying electrochemical activation, is needed to achieve the performance of commercial TiN-coated microelectrodes.

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87.85.jc	Electrical, thermal, and mechanical properties of biological matter
87.85.jj	Biocompatibility
81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
87.19.L-	Neuroscience

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Characterization studies of aluminum oxide barrier coatings on polymeric substrates

Carolin F. Struller, Peter J. Kelly, Nick J. Copeland, and Christopher M. Liauw

J. Vac. Sci. Technol. A 30, 041502 (2012); http://dx.doi.org/10.1116/1.4709451 (8 pages)

Online Publication Date: 27 April 2012

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Aluminum coatings are widely used as oxygen and water barrier layers on food packaging materials to protect the product from contamination and to extend its shelf life. Thin layers of aluminum, of the order of a few tens of nanometers, are thermally evaporated onto polymeric web in high speed roll-to-roll vacuum metallizers. More recently, transparent barrier layers, based on silica or aluminum oxide, have been introduced to allow product visibility and provide retortable, sterilizable, or microwaveable packaging. In all cases, though, the barrier characteristics are critically dependent on both the structure and properties of the coating and the nature and surface properties of the polymer film substrate. This paper, therefore, reports on characterization trials of aluminum oxide (AlO_x) coatings deposited onto polyethylene terephthalate (PET) and biaxially oriented polypropylene (BOPP) film substrates. Coating structures and properties have been investigated by scanning electron microscopy and atomic force microscopy; the influence of process parameters on barrier levels has been determined; surface energies have been determined through contact angle measurements; and coating-to-substrate adhesion has been assessed using “pull-off” tests. The main findings of this study are that the barrier performance of AlO_x coated PET and BOPP films strongly depends on the surface properties of the plain film and the aluminum oxide film growth. While AlO_x coated PET films deliver consistent barrier results, BOPP reveals considerable variations, depending on the individual substrate.

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81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.-a	Thin film structure and morphology
68.03.Cd	Surface tension and related phenomena
68.35.Np	Adhesion

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Initiated-chemical vapor deposition of organosilicon layers: Monomer adsorption, bulk growth, and process window definition

Gianfranco Aresta, Jurgen Palmans, Mauritius C. M. van de Sanden, and Mariadriana Creatore

J. Vac. Sci. Technol. A 30, 041503 (2012); http://dx.doi.org/10.1116/1.4711762 (11 pages) | Cited 1 time

Online Publication Date: 15 May 2012

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Organosilicon layers have been deposited from 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane (V₃D₃) by means of the initiated-chemical vapor deposition (i-CVD) technique in a deposition setup, ad hoc designed for the engineering of multilayer moisture permeation barriers. The application of Fourier transform infrared (FTIR) spectroscopy shows that the polymerization proceeds through the scission of the vinyl bond and allows quantifying the degree of conversion of vinyl groups, which is found to be larger than 80% for all the deposited layers. In situ real-time spectroscopic ellipsometry (SE) allows following all the i-CVD growth stages, i.e., from the initial monomer adsorption to the layer bulk growth. Finally, the combination of SE and FTIR has allowed defining the process window for the deposition of stable and highly cross-linked poly(V₃D₃) layers by tuning a key process parameter, i.e. the surface monomer adsorption.

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81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.43.Mn	Adsorption kinetics
68.65.Ac	Multilayers
78.30.Jw	Organic compounds, polymers
82.35.-x	Polymers: properties; reactions; polymerization

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In/ITO whisker and optoelectronic properties of ITO films deposited by ion beam sputtering

Jung-Hsiung Shen, Sung-Wei Yeh, and Lay Gaik Teoh

J. Vac. Sci. Technol. A 30, 041504 (2012); http://dx.doi.org/10.1116/1.4716468 (6 pages)

Online Publication Date: 15 May 2012

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ITO films were deposited on a glass substrate using ion beam sputtering, with oxygen flow rates from 0.5 to 2 sccm. The films consisted of randomly oriented ITO nanoparticles and metallic indium (In) with {101} facets, following the specific crystallographic relationship of [010]_In//[110]_ITO; (001)_In//(001)_ITO with habit planes (100)_In//(011)_ITO, when fabricated using a low oxygen flow rate. Oxygen flow rate in excess of 2.0 sccm results in the growth of amorphous films. The epitaxial In nanoparticles probably act as seeds for the development of curved ITO whiskers as small as 10 nm and extend up to 100 nm in length along the [100] direction, with poorly defined shape, possibly due to the tapering and bending of the whisker to form a tilt boundary about the [011] zone axis of the ITO. The ITO whisker growth was facilitated by the In globular tips in the vapor–liquid–solid growth mechanism. The films prepared using a series of oxygen flow rates showed different chemical-bonding states, electric resistivity and optical transparency; as a result of phase and microstructural changes.

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68.55.ag	Semiconductors
68.70.+w	Whiskers and dendrites (growth, structure, and nonelectronic properties)
73.61.Jc	Amorphous semiconductors; glasses
78.66.Jg	Amorphous semiconductors; glasses
81.05.Gc	Amorphous semiconductors
81.15.Cd	Deposition by sputtering

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Laboratory investigations of irradiated acetonitrile-containing ices on an interstellar dust analog

Ali G. M. Abdulgalil, Demian Marchione, Alexander Rosu-Finsen, Mark P. Collings, and Martin. R. S. McCoustra

J. Vac. Sci. Technol. A 30, 041505 (2012); http://dx.doi.org/10.1116/1.4716463 (6 pages)

Online Publication Date: 21 May 2012

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Reflection-absorption infrared spectroscopy is used to study the impact of low-energy electron irradiation of acetonitrile-containing ices, under conditions close to those in the dense star-forming regions in the interstellar medium. Both the incident electron energy and the surface coverage were varied. The experiments reveal that solid acetonitrile is desorbed from its ultrathin solid films with a cross section of the order of 10⁻¹⁷ cm². Evidence is presented for a significantly larger desorption cross section for acetonitrile molecules at the water–ice interface, similar to that previously observed for the benzene–water system.

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68.43.Mn	Adsorption kinetics
78.30.Jw	Organic compounds, polymers
78.66.Qn	Polymers; organic compounds
97.10.Bt	Star formation
68.43.Nr	Desorption kinetics
61.80.Fe	Electron and positron radiation effects

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Cross characterization of ultrathin interlayers in HfO₂ high-k stacks by angle resolved x-ray photoelectron spectroscopy, medium energy ion scattering, and grazing incidence extreme ultraviolet reflectometry

Matus Banyay, Larissa Juschkin, Eric Bersch, Daniel Franca, Michael Liehr, and Alain Diebold

J. Vac. Sci. Technol. A 30, 041506 (2012); http://dx.doi.org/10.1116/1.4718433 (13 pages)

Online Publication Date: 21 May 2012

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In order to miniaturize metal oxide semiconductor field effect transistors even further and improve their performance, channel lengths and gate dielectric thicknesses must be decreased. Traditionally deployed SiO₂ dielectrics face the difficulty of excessive leakage current and must be replaced by alternative (high-k) materials with larger dielectric permitivitties and smaller equivalent oxide thicknesses. A current focus of the industry is studying thin films of HfO₂ because they are a main candidate for the next generation of gate dielectrics. Measuring the depth profiles of the constituents of these layered systems is instructive in that it provides information about the thicknesses of the layers and the degree of intermixing between them. Here we demonstrate the use of a novel characterization technique, grazing incidence extreme ultraviolet reflectometry (GIXUVR), which utilizes short wavelength radiation from non-synchrotron sources to measure the depth profile of such thin-film structures. Depth profiles of samples from the same wafers were also measured using angle resolved x-ray photoelectron spectroscopy, medium energy ion scattering, and synchrotron GIXUVR. These measurements show the compatibility and complementarity of the results. The benefits of GIXUVR are the short measuring time (on the order of milliseconds to seconds), as well as high thickness, density, and material sensitivity due to a very efficient interaction of extreme ultraviolet light with matter.

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85.30.Tv

Field effect devices

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Influence of gamma irradiation on the C-V characteristics of the Al/SiN_x/Si MIS capacitors

Evrin Tugay, Ercan Yilmaz, and Rasit Turan

J. Vac. Sci. Technol. A 30, 041507 (2012); http://dx.doi.org/10.1116/1.4720351 (5 pages)

Online Publication Date: 21 May 2012

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The authors studied effects of gamma radiation on the electrical properties of the MOS capacitor made on SiN_x thin films with thickness of 100 nm deposited on p-type (100) silicon wafer using plasma-enhanced chemical vapor deposition method. The authors investigated the chemical bonds and their densities inside the films using Fourier transform infrared (FTIR) spectroscopy. The as-deposited and annealed samples with Al/SiN_x/Si structure as metal–insulator–semiconductor (MIS) capacitors were exposed to a 60-Co gamma radiation source with a dose rate of 0.015 Gy/S. The authors performed capacitance-voltage measurements at frequencies 10, 100, and 1000 kHz before and after radiation exposure with doses of up to 40 Gy. It was found that before gamma irradiation compared with as-deposited sample, the annealed samples exhibit less negative flatband voltages (V_fb) shift. This indicates the relative reduction in positive charge in the SiN_x:H samples. After gamma irradiation, for all samples a negative shift has been observed in V_fb, being more pronounced in the samples annealed at 700 °C. The more striking feature is that the amount of shift does not change by increasing radiation dose after first irradiation, in which we attributed what to the radiation hardening in Al/SiN_x/Si MIS capacitors.

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84.32.Tt	Capacitors
85.30.-z	Semiconductor devices

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Oxidation resistance of quintuple Ti-Al-Si-C-N coatings and associated mechanism

Guizhi Wu, Shengli Ma, Kewei Xu, Vincent Ji, and Paul K. Chu

J. Vac. Sci. Technol. A 30, 041508 (2012); http://dx.doi.org/10.1116/1.4721376 (9 pages)

Online Publication Date: 23 May 2012

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The oxidation behavior of Ti-Al-Si-C-N hard coatings with different Al contents deposited on high-speed steel and Si substrates by hybrid arc-enhanced magnetron sputtering is investigated in the temperature range of 500 °C–1000 °C. The coating hardness is maintained at around 35 GPa, and the parabolic oxidation rate constant K_p at 1000 °C decreases to 3.36 × 10⁻¹⁰ kg² m⁻⁴ s⁻¹ when the Al concentration is increased to 30 at. %, indicating that Ti-Al-Si-C-N coatings with larger Al concentrations have better oxidation resistance. X-ray diffraction, cross-sectional scanning electron microscopy, and x-ray photoelectron spectroscopy reveal a protective surface layer consisting of Al₂O₃, TiO₂, and SiO₂ that retards inward oxygen diffusion. A mechanism is proposed to elucidate the oxide formation. As a consequence of the good oxidation resistance, the Ti-Al-Si-C-N coatings have a large potential in high-speed dry cutting as well as other high temperature applications.

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81.65.Mq	Oxidation
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
62.20.Qp	Friction, tribology, and hardness
81.40.Np	Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure

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Cooling effect of nanoscale Bi₂Te₃/Sb₂Te₃ multilayered thermoelectric thin films

Mardecial Hines, Joshua Lenhardt, Ming Lu, Li Jiang, and Zhigang Xiao

J. Vac. Sci. Technol. A 30, 041509 (2012); http://dx.doi.org/10.1116/1.4725483 (4 pages)

Online Publication Date: 6 June 2012

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Managing high heat flux is one of the greatest technical challenges the integrated circuit (IC) industry is facing because the rising temperature limits device minimization and decreases its lifetime. In this paper, we report the characterization of the cooling effect of nanoscale Bi₂Te₃/Sb₂Te₃ multilayered thin films. The multilayer thin film was prepared with e-beam evaporation, and had 21 layers (5-nm-thick each layer and 105-nm-thick total). A thermoelectric device of the multilayer film, which is sandwiched between a diode temperature sensor and a platinum temperature sensor, was fabricated to measure the cooling effect. A maximum cooling temperature difference of about 3 K was obtained from the film at an applied dc electrical current of 5 mA. The nanoscale multilayer film could be integrated in the IC devices for the application of high-efficiency thermoelectric solid-state cooling.

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85.80.Fi	Thermoelectric devices
81.15.Dj	E-beam and hot filament evaporation deposition
07.20.Dt	Thermometers
07.20.Mc	Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
84.60.Rb	Thermoelectric, electrogasdynamic and other direct energy conversion
85.40.Sz	Deposition technology

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Compositional depth profiling of TaCN thin films

Christoph Adelmann, Thierry Conard, Alexis Franquet, Bert Brijs, Frans Munnik, Simon Burgess, Thomas Witters, Johan Meersschaut, Jorge A. Kittl, Wilfried Vandervorst, and Sven Van Elshocht

J. Vac. Sci. Technol. A 30, 041510 (2012); http://dx.doi.org/10.1116/1.4726261 (10 pages) | Cited 1 time

Online Publication Date: 8 June 2012

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The composition profiling of thin TaCN films was studied. For the composition profile determination using x-ray photoemission spectrometry (XPS) in combination with Ar sputtering, preferential sputtering effects of N with respect to Ta and C were found to lead to inaccurate elemental concentrations. Sputter yield calculations for the given experimental conditions allowed for the correction of a part of the error, leading to fair accuracy by reference-free measurements. Further improvement of the accuracy was demonstrated by the calibration of the XPS compositions against elastic recoil detection analysis (ERDA) results. For Auger electron spectrometry (AES) in combination with Ar sputtering, accurate results required the calibration against ERDA. Both XPS and AES allowed for a reliable and accurate determination of the compositional profiles of TaCN-based thin films after calibration. Time-of-flight secondary-ion mass spectrometry was also used to assess the composition of the TaCN films. However, the analysis was hampered by large matrix effects due to small unintentional oxygen contents in the films. Energy-dispersive x-ray spectrometry is also discussed, and it is shown that an accurate reference-free measurement of the average film concentration can be achieved.

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68.55.-a	Thin film structure and morphology
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
81.15.Cd	Deposition by sputtering
82.80.Ms	Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
82.80.Ej	X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods

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Extensive Raman spectroscopic investigation of ultrathin Co_1−xNi_xSi₂ films grown on Si(100)

Yinghua Piao, Zhiwei Zhu, Xindong Gao, Aliaksandra Karabko, Cheng Hu, Zhijun Qiu, Jun Luo, Zhi-Bin Zhang, Shi-Li Zhang, and Dongping Wu

J. Vac. Sci. Technol. A 30, 041511 (2012); http://dx.doi.org/10.1116/1.4726295 (8 pages)

Online Publication Date: 8 June 2012

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Ultrathin silicide films were formed by starting from 1–8 nm thick Co_1−xNi_x (x = 0, 0.25, 0.5, 0.75, and 1) at 350 °C–900 °C. For each composition x, there exists a critical thickness above which the transition temperature from monosilicides CoSi and NiSi to a disilicide-like phase increases with increasing film thickness. Below this thickness, the disilicide phase seems to form without exhibiting the monosilicides within the detection resolution limits of transmission electron microscopy and Raman spectroscopy. Raman spectroscopic analysis seems to indicate that Ni could be dissolved in the CoSi lattice to a certain fraction despite the fact that CoSi and NiSi are distinct with different crystallographic structures. Moreover, the disorder-induced Raman scattering in NiSi₂ is found to be enhanced by Co incorporation. The observed annealing behaviors are attributed to variations in free energy change for phase transition caused by differences in metal thickness.

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68.55.-a	Thin film structure and morphology
61.66.Fn	Inorganic compounds
61.72.Cc	Kinetics of defect formation and annealing
65.40.G-	Other thermodynamical quantities
64.70.K-	Solid-solid transitions
81.30.Hd	Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder

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Microstructure, phase transition, and interfacial chemistry of Gd₂O₃/Si(111) grown by electron-beam physical vapor deposition

Xiaojun Weng, Daniel A. Grave, Zachary R. Hughes, Douglas E. Wolfe, and Joshua A. Robinson

J. Vac. Sci. Technol. A 30, 041512 (2012); http://dx.doi.org/10.1116/1.4726266 (10 pages)

Online Publication Date: 12 June 2012

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The effects of growth temperature, film thickness, and oxygen flux on the microstructure, phase transition, and interfacial chemistry of gadolinium oxide (Gd₂O₃) films grown on Si(111) substrates by electron-beam physical vapor deposition were investigated using a combination of transmission electron microscopy (TEM), electron diffraction, scanning TEM, x-ray energy dispersive spectrometry, and electron energy loss spectrometry. The authors find that a low growth temperature (250 °C) and a high oxygen flux (200 sccm) led to a small grain size and a high porosity of the Gd₂O₃ film. Lowering the oxygen flux to 50 sccm led to reduced film porosity, presumably due to the increased diffusion length of the Gd atoms on the surface. Increasing the growth temperature to 650 °C resulted in a film with large columnar grains and elongated pores at the grain boundaries. Thin films grown at 250 °C consisted of cubic Gd₂O₃, but thermodynamically less stable monoclinic phase formed as the film thickness increased. Lowering the oxygen flux apparently further promoted the formation of the monoclinic phase. Furthermore, monoclinic phase dominated in the films grown at 650 °C. Such phase transitions may be related to the stress evolution of the films at different temperatures, thicknesses, and oxygen fluxes. Enhanced Gd₂O₃/Si interfacial reaction was observed as the growth temperature, film thickness, and oxygen flux increased. Moreover, oxygen was found to play a crucial role in the Gd₂O₃/Si interfacial reaction and the formation of Gd-Si-O interface layers, which proceeded by the reaction of excess oxygen with Si followed by the intermixing of SiO_x and Gd₂O₃.

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68.55.A-	Nucleation and growth
81.15.Jj	Ion and electron beam-assisted deposition; ion plating
82.45.Jn	Surface structure, reactivity and catalysis
82.80.Ej	X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods
61.72.Mm	Grain and twin boundaries

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Indium and impurity incorporation in InGaN films on polar, nonpolar, and semipolar GaN orientations grown by ammonia molecular beam epitaxy

David A. Browne, Erin C. Young, Jordan R. Lang, Christophe A. Hurni, and James S. Speck

J. Vac. Sci. Technol. A 30, 041513 (2012); http://dx.doi.org/10.1116/1.4727967 (8 pages) | Cited 8 times

Online Publication Date: 13 June 2012

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The effects of NH₃ flow, group III flux, and substrate growth temperature on indium incorporation and surface morphology have been investigated for bulk InGaN films grown by ammonia molecular beam epitaxy. The incorporation of unintentional impurity elements (H, C, O) in InGaN films was studied as a function of growth temperature for growth on polar (0001) GaN on sapphire templates, nonpolar (10 math

0) bulk GaN, and semipolar (11 math

2), (20

1) bulk GaN substrates. Enhanced indium incorporation was observed on both (10 math

0) and (20 math

1) surfaces relative to c-plane, while reduced indium incorporation was observed on (11 math

2) for co-loaded conditions. Indium incorporation was observed to increase with decreasing growth temperature for all planes, while being relatively unaffected by the group III flux rates for a 1:1 Ga:In ratio. Indium incorporation was found to increase at the expense of a decreased growth rate for higher ammonia flows; however, smooth surface morphology was consistently observed for growth on semipolar orientations. Increased concentrations of oxygen and hydrogen were observed on semipolar and nonpolar orientations with a clear trend of increased hydrogen incorporation with indium content.

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68.55.ag	Semiconductors
81.15.Hi	Molecular, atomic, ion, and chemical beam epitaxy
68.35.bg	Semiconductors
68.55.Ln	Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.uj	III-V and II-VI semiconductors

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Spectroscopic ellipsometry of superparamagnetic nanoparticles in thin films of poly(N-isopropylacrylamide)

Sebastian Rauch, Klaus-Jochen Eichhorn, Manfred Stamm, and Petra Uhlmann

J. Vac. Sci. Technol. A 30, 041514 (2012); http://dx.doi.org/10.1116/1.4727737 (8 pages) | Cited 1 time

Online Publication Date: 15 June 2012

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The versatility of spectroscopic Vis-ellipsometry (SE) to determine thin film properties was used to study Fe₃O₄-nanoparticles (NPs) embedded in thin films of poly(N-isopropylacrylamide). By using the optical constants of bulk Fe₃O₄ (magnetite) the volume fractions in different NP-polymer composites (0–3 vol. %) could be quantified with SE and verified with scanning electron microscopy (SEM) and atomic force microscopy. It was found that the best-fit results from SE matched well with data from SEM until 1 vol. %. The effect of the NP on the evolution of film thickness and surface morphology was analyzed. Over the whole concentration range the data obtained from SE measurements matched well with the suspended values and showed an expected linear behavior. Additionally, the optical constants (n and k) of the nanocomposites were extracted and compared to the pure polymer film. In the measured spectral range the data showed a physical meaningful behavior and the influence of the NP on the optical properties of the thin films could be observed.

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75.50.Tt	Fine-particle systems; nanocrystalline materials
75.20.-g	Diamagnetism, paramagnetism, and superparamagnetism
75.70.-i	Magnetic properties of thin films, surfaces, and interfaces
78.20.Ci	Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

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Permeability and corrosion in ZrO₂/Al₂O₃ nanolaminate and Al₂O₃ thin films grown by atomic layer deposition on polymers

Peter F. Carcia, Robert S. McLean, Zhigang G. Li, Michael H. Reilly, and Will J. Marshall

J. Vac. Sci. Technol. A 30, 041515 (2012); http://dx.doi.org/10.1116/1.4729447 (5 pages) | Cited 3 times

Online Publication Date: 19 June 2012

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The authors studied moisture permeation and corrosion in Al₂O₃ and Al₂O₃/ZrO₂ nanolaminate (NL) thin films grown by atomic layer deposition (ALD) at 100 °C on polyester substrates. A percolation model accurately described the dependence of permeation on the volume fraction of ZrO₂ in the nanolaminates. As the fraction of ZrO₂ was reduced to ∼0.5, moisture permeation in the NLs approached the measurement limit ∼1 × 10⁻⁴ g-H₂O/m²-day, equivalent to Al₂O₃ with the same total thickness. However, resistance to corrosion by water was modestly better for Al₂O₃ than for the NL, and we proposed that corrosion in ALD Al₂O₃ films was associated with hydrogen incorporation and a consequent film chemical composition that is an oxy-hydroxide, AlO_x(OH)_3−2x. The authors present x-ray diffraction evidence for conversion of ALD Al₂O₃ to hydroxide corrosion products, AlO(OH) and Al(OH)₃, after aging films in damp heat (85 °C/85% relative humidity) for two weeks.

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68.55.A-	Nucleation and growth
61.41.+e	Polymers, elastomers, and plastics
81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.40.Cd	Solid solution hardening, precipitation hardening, and dispersion hardening; aging
81.65.Kn	Corrosion protection
82.80.-d	Chemical analysis and related physical methods of analysis

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Magnetron-sputter epitaxy of β-FeSi₂(220)/Si(111) and β-FeSi₂(431)/Si(001) thin films at elevated temperatures

Hongfei Liu, Chengcheh Tan, and Dongzhi Chi

J. Vac. Sci. Technol. A 30, 041516 (2012); http://dx.doi.org/10.1116/1.4731200 (5 pages)

Online Publication Date: 27 June 2012

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β-FeSi₂ thin films have been grown on Si(111) and Si(001) substrates by magnetron-sputter epitaxy at 700 °C. On Si(111), the growth is consistent with the commonly observed orientation of [001]β-FeSi₂(220)//[1-10]Si(111) having three variants, in-plane rotated 120° with respect to one another. However, on Si(001), under the same growth conditions, the growth is dominated by [-111]β-FeSi₂(431)//[110]Si(001) with four variants, which is hitherto unknown for growing β-FeSi₂. Photoelectron spectra reveal negligible differences in the valance-band and Fe2p core-level between β-FeSi₂ grown on Si(111) and Si(001) but an apparent increased Si-oxidization on the surface of β-FeSi₂/Si(001). This phenomenon is discussed and attributed to the Si-surface termination effect, which also suggests that the Si/Fe ratio on the surface of β-FeSi₂(431)/Si(001) is larger than that on the surface of β-FeSi₂(220)/Si(111).

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81.05.Hd	Other semiconductors
81.15.Cd	Deposition by sputtering
81.15.Kk	Vapor phase epitaxy; growth from vapor phase
81.65.Mq	Oxidation
79.60.Dp	Adsorbed layers and thin films
73.20.At	Surface states, band structure, electron density of states

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