Formation process of graphite film on Ni substrate with improved thickness uniformity through precipitation control

Science.gov (United States)

Kim, Seul-Gi; Hu, Qicheng; Nam, Ki-Bong; Kim, Mun Ja; Yoo, Ji-Beom

2018-04-01

Large-scale graphitic thin film with high thickness uniformity needs to be developed for industrial applications. Graphitic films with thicknesses ranging from 3 to 20 nm have rarely been reported, and achieving the thickness uniformity in that range is a challenging task. In this study, a process for growing 20 nm-thick graphite films on Ni with improved thickness uniformity is demonstrated and compared with the conventional growth process. In the film grown by the process, the surface roughness and coverage were improved and no wrinkles were observed. Observations of the film structure reveal the reasons for the improvements and growth mechanisms.

Structural and morphological characterizations of ZnO films grown on GaAs substrates by MOCVD

Energy Technology Data Exchange (ETDEWEB)

Agouram, S.; Zuniga Perez, J.; Munoz-Sanjose, V. [Universitat de Valencia, Departamento de Fisica Aplicada y Electromagnetismo, Burjassot (Spain)

2007-07-15

ZnO films were grown on GaAs(100), GaAs(111)A and GaAs(111)B substrates by metal organic chemical vapour deposition (MOCVD). Diethylzinc (DEZn) and tertiarybutanol (t-butanol) were used as Zn and O precursors, respectively. The influence of the growth temperature and GaAs substrate orientation on the crystalline orientation and morphology of the ZnO grown films has been analysed. Crystallinity of grown films was studied by X-ray diffraction (XRD); thickness and morphology of ZnO films were investigated by scanning electron microscopy (SEM). SEM results reveal significant differences between morphologies depending on growth temperature but not significant differences were detected on the texture of grown films. (orig.)

Structural and interfacial characteristics of thin (2 films grown by electron cyclotron resonance plasma oxidation on [100] Si substrates

International Nuclear Information System (INIS)

Nguyen, T.D.; Carl, D.A.; Hess, D.W.; Lieberman, M.A.; Gronsky, R.

1991-04-01

The feasibility of fabricating ultra-thin SiO 2 films on the order of a few nanometer thickness has been demonstrated. SiO 2 thin films of approximately 7 nm thickness have been produced by ion flux-controlled Electron Cyclotron Resonance plasma oxidation at low temperature on [100] Si substrates, in reproducible fashion. Electrical measurements of these films indicate that they have characteristics comparable to those of thermally grown oxides. The thickness of the films was determined by ellipsometry, and further confirmed by cross-sectional High-Resolution Transmission Electron Microscopy. Comparison between the ECR and the thermal oxide films shows that the ECR films are uniform and continuous over at least a few microns in lateral direction, similar to the thermal oxide films grown at comparable thickness. In addition, HRTEM images reveal a thin (1--1.5 nm) crystalline interfacial layer between the ECR film and the [100] substrate. Thinner oxide films of approximately 5 nm thickness have also been attempted, but so far have resulted in nonuniform coverage. Reproducibility at this thickness is difficult to achieve

Effects of film thickness on scintillation characteristics of columnar CsI:Tl films exposed to high gamma radiation doses

Energy Technology Data Exchange (ETDEWEB)

Shinde, Seema; Singh, S.G.; Sen, S.; Gadkari, S.C., E-mail: gadkari@barc.gov.in

2016-02-21

Oriented columnar films of Tl doped CsI (CsI:Tl) of varying thicknesses from 50 µm to 1000 µm have been deposited on silica glass substrates by a thermal evaporation technique. The SEM micrographs confirmed the columnar structure of the film while the powder X-ray diffraction pattern recorded for the films revealed a preferred orientation of the grown columns along the <200> direction. Effects of high energy gamma exposure up to 1000 Gy on luminescence properties of the films were investigated. Results of radio-luminescence, photo-luminescence and scintillation studies on the films are compared with those of a CsI:Tl single crystal with similar thickness. A possible correlation between the film thicknesses and radiation damage in films has been observed. - Highlights: • CsI:Tl films of different thicknesses deposited for γ and α detection. • Pulse-height spectra found to degrade with increasing thickness. • Radiation damage is found more in films than single crystal of comparable thickness. • Detection efficiency increases for γ while it is invariant for α beyond 50 µm.

Effects of film thickness on scintillation characteristics of columnar CsI:Tl films exposed to high gamma radiation doses

International Nuclear Information System (INIS)

Shinde, Seema; Singh, S.G.; Sen, S.; Gadkari, S.C.

2016-01-01

Oriented columnar films of Tl doped CsI (CsI:Tl) of varying thicknesses from 50 µm to 1000 µm have been deposited on silica glass substrates by a thermal evaporation technique. The SEM micrographs confirmed the columnar structure of the film while the powder X-ray diffraction pattern recorded for the films revealed a preferred orientation of the grown columns along the direction. Effects of high energy gamma exposure up to 1000 Gy on luminescence properties of the films were investigated. Results of radio-luminescence, photo-luminescence and scintillation studies on the films are compared with those of a CsI:Tl single crystal with similar thickness. A possible correlation between the film thicknesses and radiation damage in films has been observed. - Highlights: • CsI:Tl films of different thicknesses deposited for γ and α detection. • Pulse-height spectra found to degrade with increasing thickness. • Radiation damage is found more in films than single crystal of comparable thickness. • Detection efficiency increases for γ while it is invariant for α beyond 50 µm.

Rutile TiO2 thin films grown by reactive high power impulse magnetron sputtering

International Nuclear Information System (INIS)

Agnarsson, B.; Magnus, F.; Tryggvason, T.K.; Ingason, A.S.; Leosson, K.; Olafsson, S.; Gudmundsson, J.T.

2013-01-01

Thin TiO 2 films were grown on Si(001) substrates by reactive dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS) at temperatures ranging from 300 to 700 °C. Optical and structural properties of films were compared both before and after post-annealing using scanning electron microscopy, low angle X-ray reflection (XRR), grazing incidence X-ray diffractometry and spectroscopic ellipsometry. Both dcMS- and HiPIMS-grown films reveal polycrystalline rutile TiO 2 , even prior to post-annealing. The HiPIMS-grown films exhibit significantly larger grains compared to that of dcMC-grown films, approaching 100% of the film thickness for films grown at 700 °C. In addition, the XRR surface roughness of HiPIMS-grown films was significantly lower than that of dcMS-grown films over the whole temperature range 300–700 °C. Dispersion curves could only be obtained for the HiPIMS-grown films, which were shown to have a refractive index in the range of 2.7–2.85 at 500 nm. The results show that thin, rutile TiO 2 films, with high refractive index, can be obtained by HiPIMS at relatively low growth temperatures, without post-annealing. Furthermore, these films are smoother and show better optical characteristics than their dcMS-grown counterparts. - Highlights: • We demonstrate growth of rutile TiO 2 on Si (111) by high power impulse magnetron sputtering. • The films exhibit significantly larger grains than dc magnetron sputtered films • TiO 2 films with high refractive index are obtained without post-growth annealing

Electrical resistivity of CuAlMo thin films grown at room temperature by dc magnetron sputtering

OpenAIRE

Birkett, Martin; Penlington, Roger

2016-01-01

We report on the thickness dependence of electrical resistivity of CuAlMo films grown by dc magnetron sputtering on glass substrates at room temperature. The electrical resistance of the films was monitored in situ during their growth in the thickness range 10–1000 nm. By theoretically modelling the evolution of resistivity during growth we were able to gain an insight into the dominant electrical conduction mechanisms with increasing film thickness. For thicknesses in the range 10–25 nm the ...

Optical properties of aluminum nitride thin films grown by direct-current magnetron sputtering close to epitaxy

Energy Technology Data Exchange (ETDEWEB)

Stolz, A. [Institut d' Electronique de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, PRES Lille, Université Nord de France, Avenue Poincaré, 59652 Villeneuve d' Ascq Cedex (France); Soltani, A., E-mail: ali.soltani@iemn.univ-lille1.fr [Institut d' Electronique de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, PRES Lille, Université Nord de France, Avenue Poincaré, 59652 Villeneuve d' Ascq Cedex (France); Abdallah, B. [Department of Materials Physics, Atomic Energy Commission of Syria, Damascus, P.O. Box 6091 (Syrian Arab Republic); Charrier, J. [Fonctions Optiques pour les Technologies de l' informatiON (FOTON), UMR CNRS 6082, 6, rue de Kerampont CS 80518, 22305 Lannion Cedex (France); Deresmes, D. [Institut d' Electronique de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, PRES Lille, Université Nord de France, Avenue Poincaré, 59652 Villeneuve d' Ascq Cedex (France); Jouan, P.-Y.; Djouadi, M.A. [Institut des Matériaux Jean Rouxel – IMN, UMR CNRS 6502, 2, rue de la Houssinère BP 32229, 44322 Nantes (France); Dogheche, E.; De Jaeger, J.-C. [Institut d' Electronique de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, PRES Lille, Université Nord de France, Avenue Poincaré, 59652 Villeneuve d' Ascq Cedex (France)

2013-05-01

Low-temperature Aluminum Nitride (AlN) thin films with a thickness of 3 μm were deposited by Direct-Current magnetron sputtering on sapphire substrate. They present optical properties similar to those of epitaxially grown films. Different characterization methods such as X-Ray Diffraction, Transmission Electron Microscopy and Atomic Force Microscopy were used to determine the structural properties of the films such as its roughness and crystallinity. Newton interferometer was used for stress measurement of the films. Non-destructive prism-coupling technique was used to determine refractive index and thickness homogeneity by a mapping on the whole sample area. Results show that AlN films grown on AlGaN layer have a high crystallinity close to epitaxial films, associated to a low intrinsic stress for low thickness. These results highlight that it is possible to grow thick sample with microstructure and optical properties close to epitaxy, even on a large surface. - Highlights: ► Aluminum Nitride sputtering technique with a low temperature growth process ► Epitaxial quality of two microns sputtered Aluminum Nitride film ► Optics as a non-destructive accurate tool for acoustic wave investigation.

Structural properties of In0.53Ga0.47As epitaxial films grown on Si (111) substrates by molecular beam epitaxy

International Nuclear Information System (INIS)

Gao, Fangliang; Wen, Lei; Zhang, Xiaona; Guan, Yunfang; Li, Jingling; Zhang, Shuguang; Li, Guoqiang

2015-01-01

In 0.53 Ga 0.47 As epitaxial films are grown on 2-inch diameter Si (111) substrates by growing a low-temperature In 0.4 Ga 0.6 As buffer layer using molecular beam epitaxy. The effect of the buffer layer thickness on the as-grown In 0.53 Ga 0.47 As films is characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy and transmission electron microscopy (TEM). It is revealed that the crystalline quality and surface morphology of as-grown In 0.53 Ga 0.47 As epilayer are strongly affected by the thickness of the In 0.4 Ga 0.6 As buffer layer. From TEM investigation, we understand that the type and the distribution of dislocations of the buffer layer and the as-grown In 0.53 Ga 0.47 As film are different. We have demonstrated that the In 0.4 Ga 0.6 As buffer layer with a thickness of 12 nm can advantageously release the lattice mismatch stress between the In 0.53 Ga 0.47 As and Si substrate, ultimately leading to a high-quality In 0.53 Ga 0.47 As epitaxial film with low surface roughness. - Highlights: • We provide a simple approach to achieve high-quality In 0.53 Ga 0.47 As films on Si. • An appropriate thickness of In 0.4 Ga 0.6 As buffer layer can release mismatch strain. • High-quality In 0.53 Ga 0.47 As film is grown on Si using 12-nm-thick buffer layer. • Smooth surface In 0.53 Ga 0.47 As film is grown on Si using 12-nm-thick buffer layer

Epitaxial growth and characterization of approximately 300-nm-thick AlInN films nearly lattice-matched to c-plane GaN grown on sapphire

Science.gov (United States)

Miyoshi, Makoto; Yamanaka, Mizuki; Egawa, Takashi; Takeuchi, Tetsuya

2018-05-01

AlInN epitaxial films with film thicknesses up to approximately 300 nm were grown nearly lattice-matched to a c-plane GaN-on-sapphire template by metalorganic chemical vapor deposition. The AlInN films showed relative good crystal qualities and flat surfaces, despite the existence of surface pits connected to dislocations in the underlying GaN film. The refractive index derived in this study agreed well with a previously reported result obtained over the whole visible wavelength region. The extinction coefficient spectrum exhibited a clear absorption edge, and the bandgap energy for AlInN nearly lattice-matched to GaN was determined to be approximately 4.0 eV.

TiO2 thin and thick films grown on Si/glass by sputtering of titanium targets in an RF inductively coupled plasma

International Nuclear Information System (INIS)

Valencia-Alvarado, R; López-Callejas, R; Mercado-Cabrera, A; Peña-Eguiluz, R; Muñoz-Castro, A E; Rodríguez-Méndez, B G; De la Piedad-Beneitez, A; De la Rosa-Vázquez, J M

2015-01-01

TiO 2 thin and thick films were deposited on silicon/glass substrates using RF inductive plasma in continuous wave. The films thickness, as well as phases control, is achieved with a gradual increase in temperature substrates varying supplied RF power or working gas pressure besides deposition time as well. The deposition conditions were: argon 80%/oxygen 20% carefully calibrated mixture of 2 to 7×10 −2 mbar as working gas pressure range. Deposition time 0.5 to 5 hours, 500 or 600 W RF power at 13.56 MHz frequency and 242-345 °C substrates temperature range. The titanium dioxide deposited on the substrates is grown by sputtering of a titanium target negatively polarized at 3-5 kV DC situated 14 mm in front of such substrates. The plasma reactor is a simple Pyrex-like glass cylindrical vessel of 50 cm long and 20 cm in diameter. Using the before describe plasma parameters we obtained films only anatase and both anatase/rutile phases with stoichiometric different. The films were characterized by X-ray photoelectron spectroscopy (XPS), stylus profilometer, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy. (paper)

Europium and samarium doped calcium sulfide thin films grown by PLD

International Nuclear Information System (INIS)

Christoulakis, S.; Suchea, M; Katsarakis, N.; Koudoumas, E

2007-01-01

Europium and samarium doped calcium sulfide thin films (CaS:Eu,Sm) with different thickness were prepared by the pulsed laser deposition technique using sintered targets. A typical homemade deposition chamber and XeCl excimer laser (308 nm) were employed and the films were deposited in helium atmosphere onto silicon and corning glass substrates. Structural investigations carried out by X-ray diffraction and atomic force microscopy showed a strong influence of the deposition parameters on the film properties. The films grown had an amorphous or polycrystalline structure depending on growth temperature and the number of pulses used, the same parameters affecting the film roughness, the grain shape and dimensions, the film thickness and the optical transmittance. This work indicates that pulsed laser deposition can be a suitable technique for the preparation of CaS:Eu,Sm thin films, the film characteristics being controlled by the growth conditions

Thickness effect on the microstructure, morphology and optoelectronic properties of ZnS films

International Nuclear Information System (INIS)

Prathap, P; Revathi, N; Subbaiah, Y P Venkata; Reddy, K T Ramakrishna

2008-01-01

Thin films of ZnS with thicknesses ranging from 100 to 600 nm have been deposited on glass substrates by close spaced thermal evaporation. All the films were grown at the same deposition conditions except the deposition time. The effect of thickness on the physical properties of ZnS films has been studied. The experimental results indicated that the thickness affects the structure, lattice strain, surface morphology and optoelectronic properties of ZnS films significantly. The films deposited at a thickness of 100 nm showed hexagonal structure whereas films of thickness 300 nm or more showed cubic structure. However, coexistence of both cubic and hexagonal structures was observed in the films of 200 nm thickness. The surface roughness of the films showed an increasing trend at higher thicknesses of the films. A blue-shift in the energy band gap along with an intense UV emission band was observed with the decrease of film thickness, which are ascribed to the quantum confinement effect. The behaviour of optical constants such as refractive index and extinction coefficient were analysed. The variation of refractive index and extinction coefficient with thickness was explained on the basis of the contribution from the packing density of the layers. The electrical resistivity as well as the activation energy were evaluated and found to decrease with the increase of film thickness. The thickness had a significant influence on the optical band gap as well as the luminescence intensity

Effect of thickness on structural and electrical properties of Al-doped ZnO films

Energy Technology Data Exchange (ETDEWEB)

Garcés, F.A., E-mail: felipe.garces@santafe-conicet.gov.ar [Instituto de Física del Litoral (CONICET-UNL), Güemes 3450, Santa Fe S3000GLN (Argentina); Budini, N. [Instituto de Física del Litoral (CONICET-UNL), Güemes 3450, Santa Fe S3000GLN (Argentina); Arce, R.D.; Schmidt, J.A. [Instituto de Física del Litoral (CONICET-UNL), Güemes 3450, Santa Fe S3000GLN (Argentina); Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2829, Santa Fe S3000AOM (Argentina)

2015-01-01

In this work, we have investigated the influence of thickness on structural and electrical properties of Al-doped ZnO films. Transparent conducting oxide films were grown by the spray pyrolysis technique from precursors prepared via the sol–gel method. We determined the structural properties of the films by performing X-ray diffraction and mosaicity measurements, which evidenced an increase of disorder and inhomogeneity between crystalline domains as the films thickened. This behavior was contrasted with results obtained from electrical measurements and was attributed to plastic deformation of the films as their thickness increased. As a result, the carrier mobility, the optical gap and the activation energy are affected due to emerging grain boundaries and a higher degree of disorder. - Highlights: • Al-doped ZnO thin films on glass with different thicknesses • Film thickness affects the morphological and electrical properties. • Increasing time deposition allows modification of resistivity and Hall mobility. • Mosaicity between crystalline domains increases with film thickness.

Effect of thickness on structural and electrical properties of Al-doped ZnO films

International Nuclear Information System (INIS)

Garcés, F.A.; Budini, N.; Arce, R.D.; Schmidt, J.A.

2015-01-01

In this work, we have investigated the influence of thickness on structural and electrical properties of Al-doped ZnO films. Transparent conducting oxide films were grown by the spray pyrolysis technique from precursors prepared via the sol–gel method. We determined the structural properties of the films by performing X-ray diffraction and mosaicity measurements, which evidenced an increase of disorder and inhomogeneity between crystalline domains as the films thickened. This behavior was contrasted with results obtained from electrical measurements and was attributed to plastic deformation of the films as their thickness increased. As a result, the carrier mobility, the optical gap and the activation energy are affected due to emerging grain boundaries and a higher degree of disorder. - Highlights: • Al-doped ZnO thin films on glass with different thicknesses • Film thickness affects the morphological and electrical properties. • Increasing time deposition allows modification of resistivity and Hall mobility. • Mosaicity between crystalline domains increases with film thickness

Equilibrium helium film in the thick film limit

International Nuclear Information System (INIS)

Klier, J.; Schletterer, F.; Leiderer, P.; Shikin, V.

2003-01-01

For the thickness of a liquid or solid quantum film, like liquid helium or solid hydrogen, there exist still open questions about how the film thickness develops in certain limits. One of these is the thick film limit, i.e., the crossover from the thick film to bulk. We have performed measurements in this range using the surface plasmon resonance technique and an evaporated Ag film deposited on glass as substrate. The thickness of the adsorbed helium film is varied by changing the distance h of the bulk reservoir to the surface of the substrate. In the limiting case, when h > 0, the film thickness approaches about 100 nm following the van der Waals law in the retarded regime. The film thickness and its dependence on h is precisely determined and theoretically modeled. The equilibrium film thickness behaviour is discussed in detail. The agreement between theory and experiment is very good

Magnetic and structural properties of Co2FeAl thin films grown on Si substrate

International Nuclear Information System (INIS)

Belmeguenai, Mohamed; Tuzcuoglu, Hanife; Gabor, Mihai; Petrisor, Traian; Tiusan, Coriolan; Berling, Dominique; Zighem, Fatih; Mourad Chérif, Salim

2015-01-01

The correlation between magnetic and structural properties of Co 2 FeAl (CFA) thin films of different thicknesses (10 nmgrown at room temperature on MgO-buffered Si/SiO 2 substrates and annealed at 600 °C has been studied. x-ray diffraction (XRD) measurements revealed an (011) out-of-plane textured growth of the films. The deduced lattice parameter increases with the film thickness. Moreover, pole figures showed no in-plane preferential growth orientation. The magneto-optical Kerr effect hysteresis loops showed the presence of a weak in-plane uniaxial anisotropy with a random easy axis direction. The coercive field, measured with the applied field along the easy axis direction, and the uniaxial anisotropy field increase linearly with the inverse of the CFA thickness. The microstrip line ferromagnetic resonance measurements for in-plane and perpendicular applied magnetic fields revealed that the effective magnetization and the uniaxial in-plane anisotropy field follow a linear variation versus the inverse CFA thickness. This allows deriving a perpendicular surface anisotropy coefficient of −1.86 erg/cm 2 . - Highlights: • Various Co 2 FeAl thin films were grown on a Si(001) substrates and annealed at 600 °C. • The thickness dependence of magnetic and structural properties has been studied. • X-ray measurements revealed an (011) out-of-plane textured growth of the films. • The easy axis coercive field varies linearly with the inverse CFA thickness. • The effective magnetization increases linearly with the inverse film thickness

Microstructures and growth mechanisms of GaN films epitaxially grown on AlN/Si hetero-structures by pulsed laser deposition at different temperatures.

Science.gov (United States)

Wang, Wenliang; Yang, Weijia; Lin, Yunhao; Zhou, Shizhong; Li, Guoqiang

2015-11-13

2 inch-diameter GaN films with homogeneous thickness distribution have been grown on AlN/Si(111) hetero-structures by pulsed laser deposition (PLD) with laser rastering technique. The surface morphology, crystalline quality, and interfacial property of as-grown GaN films are characterized in detail. By optimizing the laser rastering program, the ~300 nm-thick GaN films grown at 750 °C show a root-mean-square (RMS) thickness inhomogeneity of 3.0%, very smooth surface with a RMS surface roughness of 3.0 nm, full-width at half-maximums (FWHMs) for GaN(0002) and GaN(102) X-ray rocking curves of 0.7° and 0.8°, respectively, and sharp and abrupt AlN/GaN hetero-interfaces. With the increase in the growth temperature from 550 to 850 °C, the surface morphology, crystalline quality, and interfacial property of as-grown ~300 nm-thick GaN films are gradually improved at first and then decreased. Based on the characterizations, the corresponding growth mechanisms of GaN films grown on AlN/Si hetero-structures by PLD with various growth temperatures are hence proposed. This work would be beneficial to understanding the further insight of the GaN films grown on Si(111) substrates by PLD for the application of GaN-based devices.

Structural and magnetic properties of SmCo-based magnetic films grown by electron-beam evaporation

Energy Technology Data Exchange (ETDEWEB)

Saravanan, P., E-mail: psdrdo@gmail.com [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); Vinod, V.T.P.; Černík, Miroslav [Institute for Nanomaterials, Advanced Technologies and Innovation, Department of Natural Sciences, Technical University of Liberec, Studentská 1402/2, Liberec 1, 461 17 (Czech Republic); Vishnuraj, R.; Arout Chelvane, J.; Kamat, S.V. [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); Hsu, Jen-Hwa, E-mail: jhhsu@phys.ntu.edu.tw [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China)

2015-07-01

Sub-micron thick Sm–Co films (200 and 300 nm) with selective phase composition are grown on Si (100) substrates by electron-beam evaporation using Sm-lean alloy targets such as Sm{sub 4}Co{sub 96} and Sm{sub 8}Co{sub 92}. The structural and magnetic properties of Sm–Co films are characterized by x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and super-conducting quantum interference device (SQUID) magnetometer. The Sm–Co films obtained with the Sm{sub 4}Co{sub 96} target exhibit Sm{sub 2}Co{sub 17} as a prominent phase; while the films produced with the Sm{sub 8}Co{sub 92} target show Sm{sub 2}Co{sub 7} as a major phase. Both the Sm–Co films reveal granular morphology; however, the estimated grain size values are slightly lower in the case of Sm{sub 2}Co{sub 7} films, irrespective of their thicknesses. Coercivity (H{sub c}) values of 1.48 and 0.9 kOe are achieved for the as-grown 200-nm thick Sm{sub 2}Co{sub 17} and Sm{sub 2}Co{sub 7}-films. Temperature-dependent magnetization studies confirm that the demagnetization behaviors of these films are consistent with respect to the identified phase composition. Upon rapid thermal annealing, maximum H{sub c} value of 8.4 kOe is achieved for the 200 nm thick Sm{sub 2}Co{sub 17}-films. As far as e-beam evaporated Sm–Co films are concerned, this H{sub c} value is one of the best values reported so far. - Highlights: • Electron-beam evaporation was exploited to grow sub-μm thick Sm–Co films. • Sm{sub 2}Co{sub 7} and Sm{sub 2}Co{sub 17} magnetic phases were crystallized using Sm-lean alloy targets. • Both 200 and 300-nm thick Sm–Co films revealed distinct granular morphology. • Sm–Co films of lower thickness exhibited high H{sub c} and low M{sub s} and vice-versa. • Coercivity value of 8.4 kOe achieved for the 200-nm thick Sm{sub 2}Co{sub 17}-films after RTA.

Thick epitaxial CdTe films grown by close space sublimation on Ge substrates

Energy Technology Data Exchange (ETDEWEB)

Jiang, Q; Haliday, D P; Tanner, B K; Brinkman, A W [Department of Physics, University of Durham. Science Site, Durham, DH1 3LE (United Kingdom); Cantwell, B J; Mullins, J T; Basu, A [Durham Scientific Crystals Ltd., NetPark, Thomas Wright Way, Sedgefield, County Durham, TS21 3FD (United Kingdom)], E-mail: Q.Z.Jiang@durham.ac.uk

2009-01-07

This paper reports, for the first time, the successful growth of 200 {mu}m thick CdTe films on mis-oriented Ge(1 0 0) substrates by a cost-effective optimized close space sublimation method. It is found that, as the thickness increases to a few hundred micrometres, subgrains are formed probably as a result of the large density of dislocations and strain within the initial interfacial layers. The films are of high quality (x-ray rocking curve width {approx}100 arcsec) and high resistance ({approx}10{sup 9} {omega} cm), and are thus candidates for x-ray and {gamma}-ray detectors. (fast track communication)

Thickness-dependent coherent phonon frequency in ultrathin FeSe/SrTiO₃ films

Energy Technology Data Exchange (ETDEWEB)

Yang, Shuolong [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Sobota, Jonathan A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Leuenberger, Dominik [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Kemper, Alexander F. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lee, James J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Schmitt, Felix T. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Li, Wei [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Moore, Rob G. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Kirchmann, Patrick S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Shen, Zhi -Xun [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)

2015-06-01

Ultrathin FeSe films grown on SrTiO₃ substrates are a recent milestone in atomic material engineering due to their important role in understanding unconventional superconductivity in Fe-based materials. By using femtosecond time- and angle-resolved photoelectron spectroscopy, we study phonon frequencies in ultrathin FeSe/SrTiO₃ films grown by molecular beam epitaxy. After optical excitation, we observe periodic modulations of the photoelectron spectrum as a function of pump–probe delay for 1-unit-cell, 3-unit-cell, and 60-unit-cell thick FeSe films. The frequencies of the coherent intensity oscillations increase from 5.00 ± 0.02 to 5.25 ± 0.02 THz with increasing film thickness. By comparing with previous works, we attribute this mode to the Se A_1g phonon. The dominant mechanism for the phonon softening in 1-unit-cell thick FeSe films is a substrate-induced lattice strain. Results demonstrate an abrupt phonon renormalization due to a lattice mismatch between the ultrathin film and the substrate.

Magnetic and structural properties of Co{sub 2}FeAl thin films grown on Si substrate

Energy Technology Data Exchange (ETDEWEB)

Belmeguenai, Mohamed, E-mail: belmeguenai.mohamed@univ-paris13.fr [LSPM (CNRS-UPR 3407) 99 Avenue Jean-Baptiste Clément Université Paris 13, 93430 Villetaneuse (France); Tuzcuoglu, Hanife [LSPM (CNRS-UPR 3407) 99 Avenue Jean-Baptiste Clément Université Paris 13, 93430 Villetaneuse (France); Gabor, Mihai; Petrisor, Traian [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Street Memorandumului No. 28, RO-400114 Cluj-Napoca (Romania); Tiusan, Coriolan [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Street Memorandumului No. 28, RO-400114 Cluj-Napoca (Romania); Institut Jean Lamour, CNRS, Université de Nancy, BP 70239, F-54506 Vandoeuvre (France); Berling, Dominique [IS2M (CNRS-LRC 7228), 15 rue Jean Starcky, Université de Haute-Alsace, BP 2488, 68057 Mulhouse-Cedex (France); Zighem, Fatih; Mourad Chérif, Salim [LSPM (CNRS-UPR 3407) 99 Avenue Jean-Baptiste Clément Université Paris 13, 93430 Villetaneuse (France)

2015-01-01

The correlation between magnetic and structural properties of Co{sub 2}FeAl (CFA) thin films of different thicknesses (10 nmgrown at room temperature on MgO-buffered Si/SiO{sub 2} substrates and annealed at 600 °C has been studied. x-ray diffraction (XRD) measurements revealed an (011) out-of-plane textured growth of the films. The deduced lattice parameter increases with the film thickness. Moreover, pole figures showed no in-plane preferential growth orientation. The magneto-optical Kerr effect hysteresis loops showed the presence of a weak in-plane uniaxial anisotropy with a random easy axis direction. The coercive field, measured with the applied field along the easy axis direction, and the uniaxial anisotropy field increase linearly with the inverse of the CFA thickness. The microstrip line ferromagnetic resonance measurements for in-plane and perpendicular applied magnetic fields revealed that the effective magnetization and the uniaxial in-plane anisotropy field follow a linear variation versus the inverse CFA thickness. This allows deriving a perpendicular surface anisotropy coefficient of −1.86 erg/cm{sup 2}. - Highlights: • Various Co{sub 2}FeAl thin films were grown on a Si(001) substrates and annealed at 600 °C. • The thickness dependence of magnetic and structural properties has been studied. • X-ray measurements revealed an (011) out-of-plane textured growth of the films. • The easy axis coercive field varies linearly with the inverse CFA thickness. • The effective magnetization increases linearly with the inverse film thickness.

Surface plasmon resonances of Ag-Au alloy nanoparticle films grown by sequential pulsed laser deposition at different compositions and temperatures

Energy Technology Data Exchange (ETDEWEB)

Verma, Shweta, E-mail: shwetaverma@rrcat.gov.in; Rao, B. T.; Detty, A. P.; Kukreja, L. M. [Laser Materials Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India); Ganesan, V.; Phase, D. M. [UGC-DAE Consortium for Scientific Research, Indore 452 001 (India); Rai, S. K. [Indus Synchrotons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India); Bose, A.; Joshi, S. C. [Proton Linac and Superconducting Cavities Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)

2015-04-07

We studied localized surface plasmon resonances (LSPR) at different compositions, substrate temperatures, and mass thicknesses of Ag-Au alloy nanoparticle films grown by sequential pulsed laser deposition. The LSPRs were pronounced at all compositions of the films grown at high substrate temperature of about 300 °C as compared to those grown at room temperature. The alloy formation and composition of the films were determined using X-ray photoelectron and energy dispersive spectroscopy. Films' mass thickness and compositional uniformity along the thickness were determined using X-ray reflectometry and secondary ion mass spectroscopy. Atomic force microscopic analysis revealed the formation of densely packed nanoparticles of increasing size with the number of laser ablation pulses. The LSPR wavelength red shifted with increasing either Au percentage or film mass thickness and corresponding LSPR tuning was obtained in the range of 450 to 690 nm. The alloy dielectric functions obtained from three different models were compared and the optical responses of the nanoparticle films were calculated from modified Yamaguchi effective medium theory. The tuning of LSPR was found to be due to combined effect of change in intrinsic and extrinsic parameters mainly the composition, morphology, particle-particle, and particle-substrate interactions.

Thickness-dependent piezoelectric behaviour and dielectric properties of lanthanum modified BiFeO3 thin films

Directory of Open Access Journals (Sweden)

Glenda Biasotto

2011-03-01

Full Text Available Bi0.85La0.15FeO3 (BLFO thin films were deposited on Pt(111/Ti/SiO2 /Si substrates by the soft chemical method. Films with thicknesses ranging from 140 to 280 nm were grown on platinum coated silicon substrates at 500°C for 2 hours. The X-ray diffraction analysis of BLFO films evidenced a hexagonal structure over the entire thickness range investigated. The grain size of the film changes as the number of the layers increases, indicating thickness dependence. It is found that the piezoelectric response is strongly influenced by the film thickness. It is shown that the properties of BiFeO3 thin films, such as lattice parameter, dielectric permittivity, piezoeletric coefficient etc., are functions of misfit strains.

High quality atomically thin PtSe2 films grown by molecular beam epitaxy

Science.gov (United States)

Yan, Mingzhe; Wang, Eryin; Zhou, Xue; Zhang, Guangqi; Zhang, Hongyun; Zhang, Kenan; Yao, Wei; Lu, Nianpeng; Yang, Shuzhen; Wu, Shilong; Yoshikawa, Tomoki; Miyamoto, Koji; Okuda, Taichi; Wu, Yang; Yu, Pu; Duan, Wenhui; Zhou, Shuyun

2017-12-01

Atomically thin PtSe2 films have attracted extensive research interests for potential applications in high-speed electronics, spintronics and photodetectors. Obtaining high quality thin films with large size and controlled thickness is critical. Here we report the first successful epitaxial growth of high quality PtSe2 films by molecular beam epitaxy. Atomically thin films from 1 ML to 22 ML have been grown and characterized by low-energy electron diffraction, Raman spectroscopy and x-ray photoemission spectroscopy. Moreover, a systematic thickness dependent study of the electronic structure is revealed by angle-resolved photoemission spectroscopy (ARPES), and helical spin texture is revealed by spin-ARPES. Our work provides new opportunities for growing large size single crystalline films to investigate the physical properties and potential applications of PtSe2.

Hydrothermally synthesized PZT film grown in highly concentrated KOH solution with large electromechanical coupling coefficient for resonator

Science.gov (United States)

Feng, Guo-Hua; Lee, Kuan-Yi

2017-12-01

This paper presents a study of lead zirconate titanate (PZT) films hydrothermally grown on a dome-shaped titanium diaphragm. Few articles in the literature address the implementation of hydrothermal PZT films on curved-diaphragm substrates for resonators. In this study, a 50-μm-thick titanium sheet is embossed using balls of designed dimensions to shape a dome-shaped cavity array. Through single-process hydrothermal synthesis, PZT films are grown on both sides of the processed titanium diaphragm with good adhesion and uniformity. The hydrothermal synthesis process involves a high concentration of potassium hydroxide solution and excess amounts of lead acetate and zirconium oxychloride octahydrate. Varied deposition times and temperatures of PZT films are investigated. The grown films are characterized by X-ray diffraction and scanning electron microscopy. The 10-μm-thick PZT dome-shaped resonators with 60- and 20-μm-thick supporting layers are implemented and further tested. Results for both resonators indicate that large electromechanical coupling coefficients and a series resonance of 95 MHz from 14 MHz can be attained. The device is connected to a complementary metal-oxide-semiconductor integrated circuit for analysis of oscillator applications. The oscillator reaches a Q value of 6300 in air. The resonator exhibits a better sensing stability when loaded with water when compared with air.

Yttria and ceria doped zirconia thin films grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Saporiti, F.; Juarez, R. E., E-mail: cididi@fi.uba.ar [Grupo de Materiales Avanzados, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina); Audebert, F. [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Boudard, M. [Laboratoire des Materiaux et du Genie Physique (CNRS), Grenoble (France)

2013-11-01

The Yttria stabilized Zirconia (YSZ) is a standard electrolyte for solid oxide fuel cells (SOFCs), which are potential candidates for next generation portable and mobile power sources. YSZ electrolyte thin films having a cubic single phase allow reducing the SOFC operating temperature without diminishing the electrochemical power density. Films of 8 mol% Yttria stabilized Zirconia (8YSZ) and films with addition of 4 weight% Ceria (8YSZ + 4CeO{sub 2}) were grown by pulsed laser deposition (PLD) technique using 8YSZ and 8YSZ + 4CeO{sub 2} targets and a Nd-YAG laser (355 nm). Films have been deposited on Soda-Calcia-Silica glass and Si(100) substrates at room temperature. The morphology and structural characteristics of the samples have been studied by means of X-ray diffraction and scanning electron microscopy. Films of a cubic-YSZ single phase with thickness in the range of 1-3 Micro-Sign m were grown on different substrates (author)

Synthesis of thick diamond films by direct current hot-cathode plasma chemical vapour deposition

CERN Document Server

Jin Zeng Sun; Bai Yi Zhen; Lu Xian Yi

2002-01-01

The method of direct current hot-cathode plasma chemical vapour deposition has been established. A long-time stable glow discharge at large discharge current and high gas pressure has been achieved by using a hot cathode in the temperature range from 1100 degree C to 1500 degree C and non-symmetrical configuration of the poles, in which the diameter of the cathode is larger than that of anode. High-quality thick diamond films, with a diameter of 40-50 mm and thickness of 0.5-4.2 mm, have been synthesized by this method. Transparent thick diamond films were grown over a range of growth rates between 5-10 mu m/h. Most of the thick diamond films have thermal conductivities of 10-12 W/K centre dot cm. The thick diamond films with high thermal conductivity can be used as a heat sink of semiconducting laser diode array and as a heat spreading and isolation substrate of multichip modules. The performance can be obviously improved

Triboelectric charge generation by semiconducting SnO2 film grown by atomic layer deposition

Science.gov (United States)

Lee, No Ho; Yoon, Seong Yu; Kim, Dong Ha; Kim, Seong Keun; Choi, Byung Joon

2017-07-01

Improving the energy harvesting efficiency of triboelectric generators (TEGs) requires exploring new types of materials that can be used, and understanding their properties. In this study, we have investigated semiconducting SnO2 thin films as friction layers in TEGs, which has not been explored thus far. Thin films of SnO2 with various thicknesses were grown by atomic layer deposition on Si substrates. Either polymer or glass was used as counter friction layers. Vertical contact/separation mode was utilized to evaluate the TEG efficiency. The results indicate that an increase in the SnO2 film thickness from 5 to 25 nm enhances the triboelectric output voltage of the TEG. Insertion of a 400-nm-thick Pt sub-layer between the SnO2 film and Si substrate further increased the output voltage up to 120 V in a 2 cm × 2 cm contact area, while the enhancement was cancelled out by inserting a 10-nm-thick insulating Al2O3 film between SnO2 and Pt films. These results indicate that n-type semiconducting SnO2 films can provide triboelectric charge to counter-friction layers in TEGs.[Figure not available: see fulltext.

Elastically strained and relaxed La0.67Ca0.33MnO3 films grown on lanthanum aluminate substrates with different orientations

Science.gov (United States)

Boikov, Yu. A.; Serenkov, I. T.; Sakharov, V. I.; Claeson, T.

2016-12-01

Structure of 40-nm thick La0.67Ca0.33MnO3 (LCMO) films grown by laser evaporation on (001) and (110) LaAlO3 (LAO) substrates has been investigated using the methods of medium-energy ion scattering and X-ray diffraction. The grown manganite layers are under lateral biaxial compressive mechanical stresses. When (110)LAO wafers are used as the substrates, stresses relax to a great extent; the relaxation is accompanied by the formation of defects in a (3-4)-nm thick manganite-film interlayer adjacent to the LCMO-(110)LAO interface. When studying the structure of the grown layers, their electro- and magnetotransport parameters have been measured. The electroresistance of the LCMO films grown on the substrates of both types reached a maximum at temperature T M of about 250 K. At temperatures close to T M magnetoresistance of the LCMO/(110)LAO films exceeds that of the LCMO/(001)LAO films by 20-30%; however, the situation is inverse at low temperatures ( T < 150 K). At T < T M , the magnetotransport in the grown manganite films significantly depends on the spin ordering in ferromagnetic domains, which increase with a decrease in temperature.

Use of buffy coat thick films in detecting malaria parasites in patients with negative conventional thick films.

Science.gov (United States)

Duangdee, Chatnapa; Tangpukdee, Noppadon; Krudsood, Srivicha; Wilairatana, Polrat

2012-04-01

To determine the frequency of malaria parasite detection from the buffy coat blood films by using capillary tube in falciparum malaria patients with negative conventional thick films. Thirty six uncomplicated falciparum malaria patients confirmed by conventional thick and thin films were included in the study. The patients were treated with artemisinin combination therapy at Hospital for Tropical Diseases, Bangkok, Thailand for 28 day. Fingerpricks for conventional blood films were conducted every 6 hours until negative parasitemia, then daily fingerpricks for parasite checks were conducted until the patients were discharged from hospital. Blood samples were also concurrently collected in 3 heparinized capillary tubes at the same time of fingerpricks for conventional blood films when the prior parasitemia was negative on thin films and parasitemia was lower than 50 parasites/200 white blood cells by thick film. The first negative conventional thick films were compared with buffy coat thick films for parasite identification. Out of 36 patients with thick films showing negative for asexual forms of parasites, buffy coat films could detect remaining 10 patients (27.8%) with asexual forms of Plasmodium falciparum. The study shows that buffy coat thick films are useful and can detect malarial parasites in 27.8% of patients whose conventional thick films show negative parasitemia.

Engineering of nearly strain-free ZnO films on Si(1 1 1) by tuning AlN buffer thickness

International Nuclear Information System (INIS)

Venkatachalapathy, Vishnukanthan; Galeckas, Augustinas; Lee, In-Hwan; Kuznetsov, Andrej Yu.

2012-01-01

ZnO properties were investigated as a function of AlN buffer layer thickness (0–100 nm) in ZnO/AlN/Si(1 1 1) structures grown by metal organic vapor phase epitaxy. A significant improvement of ZnO film crystallinity by tuning AlN buffer thickness was confirmed by x-ray diffraction, topography and photoluminescence measurements. An optimal AlN buffer layer thickness of 50 nm is defined, which allows for growth of nearly strain-free ZnO films. The presence of free excitons at 10 K suggests high crystal quality for all ZnO samples grown on AlN/Si(1 1 1) templates. The intensities of neutral and ionized donor bound exciton lines are found to correlate with the in-plane and out-of-plane strain in the films, respectively.

Engineering of nearly strain-free ZnO films on Si(1 1 1) by tuning AlN buffer thickness

Energy Technology Data Exchange (ETDEWEB)

Venkatachalapathy, Vishnukanthan, E-mail: vishnukanthan.venkatachalapathy@smn.uio.no [Department of Physics/Centre for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway); Galeckas, Augustinas [Department of Physics/Centre for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway); Lee, In-Hwan [School of Advanced Materials Engineering, Research Centre for Advanced Materials Development (RCAMD), Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Kuznetsov, Andrej Yu. [Department of Physics/Centre for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway)

2012-05-15

ZnO properties were investigated as a function of AlN buffer layer thickness (0-100 nm) in ZnO/AlN/Si(1 1 1) structures grown by metal organic vapor phase epitaxy. A significant improvement of ZnO film crystallinity by tuning AlN buffer thickness was confirmed by x-ray diffraction, topography and photoluminescence measurements. An optimal AlN buffer layer thickness of 50 nm is defined, which allows for growth of nearly strain-free ZnO films. The presence of free excitons at 10 K suggests high crystal quality for all ZnO samples grown on AlN/Si(1 1 1) templates. The intensities of neutral and ionized donor bound exciton lines are found to correlate with the in-plane and out-of-plane strain in the films, respectively.

Growth of BaTiO3-PVDF composite thick films by using aerosol deposition

Science.gov (United States)

Cho, Sung Hwan; Yoon, Young Joon

2016-01-01

Barium titanate (BaTiO3)-polyvinylidene fluoride (PVDF) composite thick films were grown by using aerosol deposition at room temperature with BaTiO3 and PVDF powders. To produce a uniform composition in ceramic and polymer composite films, which show a substantial difference in specific gravity, we used PVDF-coated BaTiO3 powders as the starting materials. An examination of the microstructure confirmed that the BaTiO3 were well distributed in the PVDF matrix in the form of a 0 - 3 compound. The crystallite size in the BaTiO3-PVDF composite thick films was 5 ˜ 50 times higher than that in pure BaTiO3 thick films. PVDF plays a role in suppressing the fragmentation of BaTiO3 powder during the aerosol deposition process and in controlling the relative permittivity.

Effect of film thickness, type of buffer layer, and substrate temperature on the morphology of dicyanovinyl-substituted sexithiophene films

Energy Technology Data Exchange (ETDEWEB)

Levin, Alexandr A., E-mail: alexander.levin@iapp.de [Institut fuer Angewandte Photophysik, Technische Universitaet Dresden, 01062 Dresden (Germany); Levichkova, Marieta [Institut fuer Angewandte Photophysik, Technische Universitaet Dresden, 01062 Dresden (Germany); Heliatek GmbH, 01187 Dresden (Germany); Hildebrandt, Dirk; Klisch, Marina; Weiss, Andre [Heliatek GmbH, 01187 Dresden (Germany); Wynands, David; Elschner, Chris [Institut fuer Angewandte Photophysik, Technische Universitaet Dresden, 01062 Dresden (Germany); Pfeiffer, Martin [Heliatek GmbH, 01187 Dresden (Germany); Leo, Karl; Riede, Moritz [Institut fuer Angewandte Photophysik, Technische Universitaet Dresden, 01062 Dresden (Germany)

2012-01-31

The influence of film thickness, type of buffer underlayer, and deposition substrate temperature on the crystal structure, microstructure, and morphology of the films of dicyanovinyl-substituted sexithiophene with four butyl-chains (DCV6T-Bu{sub 4}) is investigated by means of X-ray diffraction (XRD) and X-ray reflectivity methods. A neat Si wafer or a Si wafer covered by a 15 nm buffer underlayer of fullerene C{sub 60} or 9,9-Bis[4-(N,N-bis-biphenyl-4-yl-amino)phenyl]-9H-fluorene (BPAPF) is used as a substrate. The crystalline nature and ordered molecular arrangement of the films are recorded down to 6 nm film thickness. By using substrates heated up to 90 Degree-Sign C during the film deposition, the size of the DCV6T-Bu{sub 4} crystallites in direction perpendicular to the film surface increases up to value of the film thickness. With increasing deposition substrate temperature or film thickness, the DCV6T-Bu{sub 4} film relaxes, resulting in reducing the interplane distances closer to the bulk values. For the films of the same thickness deposited at the same substrate temperature, the DCV6T-Bu{sub 4} film relaxes for growth on Si to BPAPF to C{sub 60}. Thicker films grown at heated substrates are characterized by smaller density, higher roughness and crystallinity and better molecular ordering. A thin (up to about 6 nm-thick) intermediate layer with linear density-gradient is formed at the C{sub 60}/DCV6T-Bu{sub 4} interface for the films with buffer C{sub 60} layer. The XRD pattern of the DCV6T-Bu{sub 4} powder is indexed using triclinic unit cell parameters.

Influence of film thickness and Fe doping on LPG sensing properties of Mn3O4 thin film grown by SILAR method

Science.gov (United States)

Belkhedkar, M. R.; Ubale, A. U.

2018-05-01

Nanocrystalline Fe doped and undoped Mn3O4 thin films have been deposited by Successive Ionic Layer Adsorption and Reaction (SILAR) method onto glass substrates using MnCl2 and NaOH as cationic and anionic precursors. The grazing incidence X-ray diffraction (GIXRD) and field emission scanning electron microscopy (FESEM)) have been carried out to analyze structural and surface morphological properties of the films. The LPG sensing performance of Mn3O4thin films have been studied by varying temperature, concentration of LPG, thickness of the film and doping percentage of Fe. The LPG response of the Mn3O4thin films were found to be enhances with film thickness and decreases with increased Fe doping (0 to 8 wt. %) at 573 K temperature.

Polycrystalline Ba0.6Sr0.4TiO3 thin films on r-plane sapphire: Effect of film thickness on strain and dielectric properties

Science.gov (United States)

Fardin, E. A.; Holland, A. S.; Ghorbani, K.; Akdogan, E. K.; Simon, W. K.; Safari, A.; Wang, J. Y.

2006-10-01

Polycrystalline Ba0.6Sr0.4TiO3 (BST) films grown on r-plane sapphire exhibit strong variation of in-plane strain over the thickness range of 25-400nm. At a critical thickness of ˜200nm, the films are strain relieved; in thinner films, the strain is tensile, while compressive strain was observed in the 400nm film. Microwave properties of the films were measured from 1to20GHz by the interdigital capacitor method. A capacitance tunability of 64% was observed in the 200nm film, while thinner films showed improved Q factor. These results demonstrate the possibility of incorporating frequency agile BST-based devices into the silicon on sapphire process.

High resolution x-ray scattering studies of strain in epitaxial thin films of yttrium silicide grown on silicon (111)

International Nuclear Information System (INIS)

Marthinez-Miranda, L.J.; Santiago-Aviles, J.J.; Siegal, M.P.; Graham, W.R.; Heiney, P.A.

1990-01-01

The authors have used high resolution grazing incidence x-ray scattering (GIXS) to study the in- plane and out-of-plane structure of epitaxial YSi 2-x films grown on Si(111), with thicknesses ranging from 85 Angstrom to 510 Angstrom. Their results indicate that the films are strained, and that film strain increases as a function of thickness, with lattice parameters varying from a = 3.846 Angstrom/c = 4.142 Angstrom for the 85 Angstrom film to a = 3.877 Angstrom/c = 4.121 Angstrom for the 510 Angstrom film. The authors correlate these results with an increase in pinhole areal coverage as a function of thickness. In addition, the authors' measurements show no evidence for the existence of ordered silicon vacancies in the films

HoYbBIG epitaxial thick films used for Faraday rotator in the 1.55μm band

International Nuclear Information System (INIS)

Zhong, Z.W.; Xu, X.W.; Chong, T.C.; Yuan, S.N.; Li, M.H.; Zhang, G.Y.; Freeman, B.

2005-01-01

Ho 3-x-y Yb y Bi x Fe 5 O 12 (HoYbBIG) garnet thick films with Bi content of x=0.9-1.5 were prepared by the liquid phase epitaxy (LPE) method. Optical properties and magneto-optical properties were characterized. The LPE-grown HoYbBIG thick films exhibited large Faraday rotation coefficients up to 1540 o /cm at 1.55μm, and good wavelength and temperature stability

Influence of the film thickness on the structure, optical and electrical properties of ITO coatings deposited by sputtering at room temperature on glass and plastic substrates

International Nuclear Information System (INIS)

Guillén, C; Herrero, J

2008-01-01

Transparent and conductive indium tin oxide (ITO) films with thickness between 0.2 and 0.7 µm were deposited by sputtering at room temperature on glass and polyethylene terephthalate (PET) substrates. All films were polycrystalline, with crystallite size increasing and lattice distortion decreasing when the film thickness was increased. Besides, transmission in the near-infrared region is found to be decreasing and carrier concentration increasing when the film thickness was increased. For the same thickness, the lattice distortion is slightly lower and the carrier concentration higher for the layers grown on PET substrates. A direct relationship between the lattice distortion and the free carrier concentration has been established, applying to the films grown on glass and plastic substrates. By adjusting ITO coating thickness, sheet resistance below 15 Ω sq −1 and average visible transmittance about 90% have been achieved by sputtering at room temperature

Electrical resistivity of CuAlMo thin films grown at room temperature by dc magnetron sputtering

Science.gov (United States)

Birkett, Martin; Penlington, Roger

2016-07-01

We report on the thickness dependence of electrical resistivity of CuAlMo films grown by dc magnetron sputtering on glass substrates at room temperature. The electrical resistance of the films was monitored in situ during their growth in the thickness range 10-1000 nm. By theoretically modelling the evolution of resistivity during growth we were able to gain an insight into the dominant electrical conduction mechanisms with increasing film thickness. For thicknesses in the range 10-25 nm the electrical resistivity is found to be a function of the film surface roughness and is well described by Namba’s model. For thicknesses of 25-40 nm the experimental data was most accurately fitted using the Mayadas and Shatkes model which accounts for grain boundary scattering of the conduction electrons. Beyond 40 nm, the thickness of the film was found to be the controlling factor and the Fuchs-Sonheimer (FS) model was used to fit the experimental data, with diffuse scattering of the conduction electrons at the two film surfaces. By combining the Fuchs and Namba (FN) models a suitable correlation between theoretical and experimental resistivity can be achieved across the full CuAlMo film thickness range of 10-1000 nm. The irreversibility of resistance for films of thickness >200 nm, which demonstrated bulk conductivity, was measured to be less than 0.03% following subjection to temperature cycles of -55 and +125 °C and the temperature co-efficient of resistance was less than ±15 ppm °C-1.

Thick film hydrogen sensor

Science.gov (United States)

Hoffheins, Barbara S.; Lauf, Robert J.

1995-01-01

A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors.

doped ZnO thick film resistors

Indian Academy of Sciences (India)

The characterization and ethanol gas sensing properties of pure and doped ZnO thick films were investigated. Thick films of pure zinc oxide were prepared by the screen printing technique. Pure zinc oxide was almost insensitive to ethanol. Thick films of Al2O3 (1 wt%) doped ZnO were observed to be highly sensitive to ...

High quality Y-type hexaferrite thick films for microwave applications by an economical and environmentally benign crystal growth technique

Energy Technology Data Exchange (ETDEWEB)

Hu, Bolin; Chen, Yajie, E-mail: y.chen@neu.edu; Gillette, Scott; Su, Zhijuan; Harris, Vincent G. [Center for Microwave Magnetic Materials and Integrated Circuits and Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115 (United States); Wolf, Jason; McHenry, Michael E. [Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

2014-02-17

Thick barium hexaferrite Ba{sub 2}Zn{sub 2}Fe{sub 12}O{sub 22} (i.e., Zn{sub 2}Y) films having thicknesses of ∼100 μm were epitaxially grown on MgO (111) substrates using an environmentally benign ferrite-salt mixture by vaporizing the salt. X-ray diffraction pole figure analyses showed (00l) crystallographic alignment with little in plane dispersion confirming epitaxial growth. Saturation magnetization, 4πM{sub s}, was measured for as-grown films to be 2.51 ± 0.1 kG with an out of plane magnetic anisotropy field H{sub A} of 8.9 ± 0.1 kOe. Ferromagnetic resonance linewidth, as the peak-to-peak power absorption derivative at 9.6 GHz, was measured to be 62 Oe. These properties demonstrate a rapid, convenient, cost-effective, and nontoxic method of growing high quality thick crystalline ferrite films which could be used widely for microwave device applications.

Thickness dependence of the strain, band gap and transport properties of epitaxial In{sub 2}O{sub 3} thin films grown on Y-stabilised ZrO{sub 2}(111)

Energy Technology Data Exchange (ETDEWEB)

Zhang, K H L; Oropeza, F E; Egdell, R G [Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA (United Kingdom); Lazarov, V K [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Veal, T D; McConville, C F [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Walsh, A, E-mail: Russell.egdell@chem.ox.ac.uk [Department of Chemistry, Kathleen Lonsdale Materials Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

2011-08-24

Epitaxial films of In{sub 2}O{sub 3} have been grown on Y-stabilised ZrO{sub 2}(111) substrates by molecular beam epitaxy over a range of thicknesses between 35 and 420 nm. The thinnest films are strained, but display a 'cross-hatch' morphology associated with a network of misfit dislocations which allow partial accommodation of the lattice mismatch. With increasing thickness a 'dewetting' process occurs and the films break up into micron sized mesas, which coalesce into continuous films at the highest coverages. The changes in morphology are accompanied by a progressive release of strain and an increase in carrier mobility to a maximum value of 73 cm{sup 2} V{sup -1} s{sup -1}. The optical band gap in strained ultrathin films is found to be smaller than for thicker films. Modelling of the system, using a combination of classical pair-wise potentials and ab initio density functional theory, provides a microscopic description of the elastic contributions to the strained epitaxial growth, as well as the electronic effects that give rise to the observed band gap changes. The band gap increase induced by the uniaxial compression is offset by the band gap reduction associated with the epitaxial tensile strain.

BaF2 POST-DEPOSITION REACTION PROCESS FOR THICK YBCO FILMS

International Nuclear Information System (INIS)

SUENAGA, M.; SOLOVYOV, V.F.; WU, L.; WIESMANN, H.J.; ZHU, Y.

2001-01-01

The basic processes of the so-called BaF 2 process for the formation of YBa 2 Cu 3 O 7 , YBCO, films as well as its advantages over the in situ formation processes are discussed in the previous chapter. The process and the properties of YBCO films by this process were also nicely described in earlier articles by R. Feenstra, (et al.) Here, we will discuss two pertinent subjects related to fabrication of technologically viable YBCO conductors using this process. These are (1) the growth of thick (>> 1 microm) c-axis-oriented YBCO films and (2) their growth rates. Before the detail discussions of these subjects are given, we first briefly discuss what geometrical structure a YBCO-coated conductor should be. Then, we will provide examples of simple arguments for how thick the YBCO films and how fast their growth rates need to be. Then, the discussions in the following two sections are devoted to: (1) the present understanding of the nucleation and the growth process for YBCO, and why it is so difficult to grow thick c-axis-oriented films (> 3 microm), and (2) our present understanding of the YBCO growth-limiting mechanism and methods to increase the growth rates. The values of critical-current densities J c in these films are of primary importance for the applications,. and the above two subjects are intimately related to the control of J c of the films. In general, the lower the temperatures of the YBCO formation are the higher the values of J c of the films. Thus, the present discussion is limited to those films which are reacted at ∼735 C. This is the lowest temperature at which c-axis-oriented YBCO films (1-3 microm thick) are comfortably grown. It is also well known that the non-c-axis oriented YBCO platelets are extremely detrimental to the values of J c such that their effects on J c dwarf essentially all of other microstructural effects which control J c . Hence, the discussion given below is mainly focused on how to avoid the growth of these crystallites

Structural and morphological properties of ITO thin films grown by magnetron sputtering

Science.gov (United States)

Ghorannevis, Z.; Akbarnejad, E.; Ghoranneviss, M.

2015-10-01

Physical properties of transparent and conducting indium tin oxide (ITO) thin films grown by radiofrequency (RF) magnetron sputtering are studied systematically by changing deposition time. The X-ray diffraction (XRD) data indicate polycrystalline thin films with grain orientations predominantly along the (2 2 2) and (4 0 0) directions. From atomic force microscopy (AFM) it is found that by increasing the deposition time, the roughness of the film increases. Scanning electron microscopy (SEM) images show a network of a high-porosity interconnected nanoparticles, which approximately have a pore size ranging between 20 and 30 nm. Optical measurements suggest an average transmission of 80 % for the ITO films. Sheet resistances are investigated using four-point probes, which imply that by increasing the film thickness the resistivities of the films decrease to 2.43 × 10-5 Ω cm.

Comparative study of structural and electro-optical properties of ZnO:Ga films grown by steered cathodic arc plasma evaporation and sputtering on plastic and their application on polymer-based organic solar cells

Energy Technology Data Exchange (ETDEWEB)

Liang, Chih-Hao, E-mail: dataman888@hotmail.com [R& D Division, Walsin Technology Corporation, Kaohsiung, Taiwan (China); Hsiao, Yu-Jen [National Nano Device Laboratories, National Applied Research Laboratories, Tainan, Taiwan (China); Hwang, Weng-Sing [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China)

2016-08-01

Ga-doped ZnO (GZO) films with various thicknesses (105–490 nm) were deposited on PET substrates at a low temperature of 90 °C by a steered cathodic arc plasma evaporation (steered CAPE), and a GZO film with a thickness of 400 nm was deposited at 90 °C by a magnetron sputtering (MS) for comparison. The comparative analysis of the microstructure, residual stress, surface morphology, electrical and optical properties, chemical states, and doping efficiency of the films produced by the steered CAPE and MS processes was performed, and the effect of thickness on the CAPE-grown GZO films was investigated in detail. The results showed that the GZO films grown by steered CAPE exhibited higher crystallinity and lower internal stress than those deposited by MS. The transmittance and electrical properties were also enhanced for the steered CAPE-grown films. The figure of merit (Φ = T{sup 10}/R{sub s}, where T is the transmittance and R{sub s} is the sheet resistance in Ω/□). was used to evaluate the performance of the electro-optical properties. The GZO films with a thickness of 400 nm deposited by CAPE had the highest Φ value, 1.94 × 10{sup −2} Ω{sup −1}, a corresponding average visible transmittance of 88.8% and resistivity of 6.29 × 10{sup −4} Ω·cm. In contrast, the Φ value of MS-deposited GZO film with a thickness of 400 nm is only 1.1 × 10{sup −3} Ω{sup −1}. This can be attributed to the increase in crystalline size, [0001] preferred orientation, decrease in stacking faults density and Ar contamination in steered CAPE-grown films, leading to increases in the Hall mobility and carrier density. In addition, the power conversion efficiency (PCE) of organic solar cells was significantly improved by using the CAPE-grown GZO electrode, and the PCE values were 1.2% and 1.7% for the devices with MS-grown and CAPE-grown GZO electrodes, respectively. - Highlights: • ZnO:Ga (GZO) films were grown on PET by steered cathodic arc plasma evaporation (CAPE

RHEED oscillations in spinel ferrite epitaxial films grown by conventional planar magnetron sputtering

Science.gov (United States)

Ojima, T.; Tainosho, T.; Sharmin, S.; Yanagihara, H.

2018-04-01

Real-time in situ reflection high energy electron diffraction (RHEED) observations of Fe3O4, γ-Fe2O3, and (Co,Fe)3O4 films on MgO(001) substrates grown by a conventional planar magnetron sputtering was studied. The change in periodical intensity of the specular reflection spot in the RHEED images of three different spinel ferrite compounds grown by two different sputtering systems was examined. The oscillation period was found to correspond to the 1/4 unit cell of each spinel ferrite, similar to that observed in molecular beam epitaxy (MBE) and pulsed laser deposition (PLD) experiments. This suggests that the layer-by-layer growth of spinel ferrite (001) films is general in most physical vapor deposition (PVD) processes. The surfaces of the films were as flat as the surface of the substrate, consistent with the observed layer-by-layer growth process. The observed RHEED oscillation indicates that even a conventional sputtering method can be used to control film thickness during atomic layer depositions.

RHEED oscillations in spinel ferrite epitaxial films grown by conventional planar magnetron sputtering

Directory of Open Access Journals (Sweden)

T. Ojima

2018-04-01

Full Text Available Real-time in situ reflection high energy electron diffraction (RHEED observations of Fe3O4, γ-Fe2O3, and (Co,Fe3O4 films on MgO(001 substrates grown by a conventional planar magnetron sputtering was studied. The change in periodical intensity of the specular reflection spot in the RHEED images of three different spinel ferrite compounds grown by two different sputtering systems was examined. The oscillation period was found to correspond to the 1/4 unit cell of each spinel ferrite, similar to that observed in molecular beam epitaxy (MBE and pulsed laser deposition (PLD experiments. This suggests that the layer-by-layer growth of spinel ferrite (001 films is general in most physical vapor deposition (PVD processes. The surfaces of the films were as flat as the surface of the substrate, consistent with the observed layer-by-layer growth process. The observed RHEED oscillation indicates that even a conventional sputtering method can be used to control film thickness during atomic layer depositions.

Annealing Effect on the Structural and Optical Properties of Sputter-Grown Bismuth Titanium Oxide Thin Films

Directory of Open Access Journals (Sweden)

José E. Alfonso

2014-04-01

Full Text Available The aim of this work is to assess the evolution of the structural and optical properties of BixTiyOz films grown by rf magnetron sputtering upon post-deposition annealing treatments in order to obtain good quality films with large grain size, low defect density and high refractive index similar to that of single crystals. Films with thickness in the range of 220–250 nm have been successfully grown. After annealing treatment at 600 °C the films show excellent transparency and full crystallization. It is shown that to achieve larger crystallite sizes, up to 17 nm, it is better to carry the annealing under dry air than under oxygen atmosphere, probably because the nucleation rate is reduced. The refractive index of the films is similar under both atmospheres and it is very high (n =2.5 at 589 nm. However it is still slightly lower than that of the single crystal value due to the polycrystalline morphology of the thin films.

Single layer porous gold films grown at different temperatures

International Nuclear Information System (INIS)

Zhang Renyun; Hummelgard, Magnus; Olin, Hakan

2010-01-01

Large area porous gold films can be used in several areas including electrochemical electrodes, as an essential component in sensors, or as a conducting material in electronics. Here, we report on evaporation induced crystal growth of large area porous gold films at 20, 40 and 60 deg. C. The gold films were grown on liquid surface at 20 deg. C, while the films were grown on the wall of beakers when temperature increased to 40 and 60 deg. C. The porous gold films consisted of a dense network of gold nanowires as characterized by TEM and SEM. TEM diffraction results indicated that higher temperature formed larger crystallites of gold wires. An in situ TEM imaging of the coalescence of gold nanoparticles mimicked the process of the growth of these porous films, and a plotting of the coalescence time and the neck radius showed a diffusion process. The densities of these gold films were also characterized by transmittance, and the results showed film grown at 20 deg. C had the highest density, while the film grown at 60 deg. C had the lowest consistent with SEM and TEM characterization. Electrical measurements of these gold films showed that the most conductive films were the ones grown at 40 deg. C. The conductivities of the gold films were related to the amount of contamination, density and the diameter of the gold nanowires in the films. In addition, a gold film/gold nanoparticle hybrid was made, which showed a 10% decrease in transmittance during hybridization, pointing to applications as chemical and biological sensors.

QCM gas sensor characterization of ALD-grown very thin TiO2 films

Science.gov (United States)

Boyadjiev, S.; Georgieva, V.; Vergov, L.; Szilágyi, I. M.

2018-03-01

The paper presents a technology for preparation and characterization of titanium dioxide (TiO2) thin films suitable for gas sensor applications. Applying atomic layer deposition (ALD), very thin TiO2 films were deposited on quartz resonators, and their gas sensing properties were studied using the quartz crystal microbalance (QCM) method. The TiO2 thin films were grown using Ti(iOPr)4 and water as precursors. The surface of the films was observed by scanning electron microscopy (SEM), coupled with energy dispersive X-ray analysis (EDX) used for a composition study. The research was focused on the gas-sensing properties of the films. Films of 10-nm thickness were deposited on quartz resonators with Au electrodes and the QCMs were used to build highly sensitive gas sensors, which were tested for detecting NO2. Although very thin, these ALD-grown TiO2 films were sensitive to NO2 already at room temperature and could register as low concentrations as 50 ppm, while the sorption was fully reversible, and the sensors could be fully recovered. With the technology presented, the manufacturing of gas sensors is simple, fast and cost-effective, and suitable for energy-effective portable equipment for real-time environmental monitoring of NO2.

Investigation of in-pile grown corrosion films on zirconium-based alloys

International Nuclear Information System (INIS)

Gebhardt, O.; Hermann, A.; Bart, G.; Blank, H.; Ray, I.L.F.

1996-01-01

In-pile grown corrosion films on different fuel rod claddings (standard Zircaloy-4, extra low tin Zircaloy (ELS), and Zr2.5Nb) have been studied using a variety of experimental techniques. The aim of the investigations was to find out common features and differences between the corrosion layers grown on zirconium alloys having different composition. Methods applied were scanning and transmission electron microscopy (SEM, TEM), electrochemical impedance spectroscopy (EIS), and electrochemical anodization. The morphological differences have been observed between the specimens that could explain the irradiation enhancement of corrosion of Zircaloy-4. The features of the compact oxide close to the oxide/metal interface have been characterized by electrochemical methods. The relationship between the thickness of this protective oxide and the overall oxide thickness has been investigated by EIS. It was found that this relation is dependent on the location of the oxide along the fuel rod and on the corrosion rate

Effect of thickness on the structural and optical properties of CuO thin films grown by successive ionic layer adsorption and reaction

International Nuclear Information System (INIS)

Akaltun, Yunus

2015-01-01

CuO thin films were synthesised on glass substrates at room temperature using successive ionic layer adsorption and reaction (SILAR) method. The effect of film thickness on characteristic parameters such as the structural, morphological and optical properties of the films was investigated. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies showed that all of the films exhibited polycrystalline structure with monoclinic phases and covered the glass substrates well. The crystalline and morphology of the films improved with increasing film thickness. The optical band gap decreased from 2.03 to 1.79 eV depending on the film thickness. The refractive index (n), electron effective mass (m_e"⁎/m_o) and static and frequency dielectric constants (ε_o, ε_∞) were determined using the energy band gap values. - Highlights: • CuO thin films were deposited using SILAR method. • The electron effective mass, refractive index, dielectric constant values were calculated. • Characterisation of the films has been performed using XRD, SEM, Raman and optical measurements. • The d values of the planes of with thickness show no variation.

Magnetic resonance studies of the Mg acceptor in thick free-standing and thin-film GaN

Science.gov (United States)

Zvanut, Mary Ellen

Mg, the only effective p-type dopant for the nitrides, substitutes for Ga and forms an acceptor with a defect level of about 0.16 eV. The magnetic resonance of such a center should be highly anisotropic, yet early work employing both optically detected magnetic resonance (ODMR) and electron paramagnetic resonance (EPR) spectroscopies revealed a defect with a nearly isotropic g-tensor. The results were attributed to crystal fields caused by compensation and/or strain typical of the heteroepitaxially grown films. The theory was supported by observation of the expected highly anisotropic ODMR signature in homoepitaxially grown films in which dislocation-induced non-uniform strain and compensation are reduced. The talk will review EPR measurements of thin films and describe new work which takes advantage of the recently available thick free-standing GaN:Mg substrates grown by hydride vapor phase epitaxy (HVPE) and high nitrogen pressure solution growth (HNPS). Interestingly, the films and HVPE substrates exhibit characteristically different types of EPR signals, and no EPR response could be induced in the HNPS substrates, with or without illumination. In the heteroepitaxial films, a curious angular dependent line-shape is observed in addition to the nearly isotropic g-tensor characteristic of the Mg-related acceptor. On the other hand, the free-standing HVPE crystals reveal a clear signature of a highly anisotropic shallow acceptor center. Comparison with SIMS measurements implies a direct relation to the Mg impurity, and frequency-dependent EPR studies demonstrate the influence of the anisotropic crystal fields. Overall, the measurements of the thick free-standing crystals show that the Mg acceptor is strongly affected by the local environment. The ODMR was performed by Evan Glaser, NRL and the free-standing Mg-doped HVPE crystals were grown by Jacob Leach, Kyma Tech. The work at UAB is supported by NSF Grant No. DMR-1308446.

Dependence on film thickness of grain boundary low-field magnetoresistance in thin films of La0.7Ca0.3MnO3

International Nuclear Information System (INIS)

Todd, N. K.; Mathur, N. D.; Blamire, M. G.

2001-01-01

The magnetoresistance of grain boundaries in the perovskite manganites is being studied, both in polycrystalline materials, and thin films grown on bicrystal substrates, because of interest in low-field applications. In this article we show that epitaxial films grown on SrTiO 3 bicrystal substrates of 45 degree misorientation show magnetoresistance behavior which is strongly dependent on the thickness of the film. Thin films, e.g., 40 nm, can show a large low-field magnetoresistance at low temperatures, with very sharp switching between distinct high and low resistance states for fields applied in plane and parallel to the boundary. Thicker films show a more complex behavior of resistance as a function of field, and the dependence on the angle between the applied field and the grain boundary is altered. These changes in magnetoresistance behavior are linked to the variation in morphology of the films. Thin films are coherently strained, due to the mismatch with the substrate, and very smooth. Thicker films relax, with the formation of defects, and hence different micromagnetic behavior. [copyright] 2001 American Institute of Physics

Effect of growth temperature on defects in epitaxial GaN film grown by plasma assisted molecular beam epitaxy

Directory of Open Access Journals (Sweden)

S. S. Kushvaha

2014-02-01

Full Text Available We report the effect of growth temperature on defect states of GaN epitaxial layers grown on 3.5 μm thick GaN epi-layer on sapphire (0001 substrates using plasma assisted molecular beam epitaxy. The GaN samples grown at three different substrate temperatures at 730, 740 and 750 °C were characterized using atomic force microscopy and photoluminescence spectroscopy. The atomic force microscopy images of these samples show the presence of small surface and large hexagonal pits on the GaN film surfaces. The surface defect density of high temperature grown sample is smaller (4.0 × 108 cm−2 at 750 °C than that of the low temperature grown sample (1.1 × 109 cm−2 at 730 °C. A correlation between growth temperature and concentration of deep centre defect states from photoluminescence spectra is also presented. The GaN film grown at 750 °C exhibits the lowest defect concentration which confirms that the growth temperature strongly influences the surface morphology and affects the optical properties of the GaN epitaxial films.

The properties of TiN ultra-thin films grown on SiO{sub 2} substrate by reactive high power impulse magnetron sputtering under various growth angles

Energy Technology Data Exchange (ETDEWEB)

Shayestehaminzadeh, S., E-mail: ses30@hi.is [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Tryggvason, T.K. [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Karlsson, L. [School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen (Germany); Olafsson, S. [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Gudmundsson, J.T. [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); University of Michigan-Shanghai Jiao Tong University, University Joint Institute, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240 (China)

2013-12-02

Thin TiN films were grown on SiO{sub 2} by reactive high power impulse magnetron sputtering (HiPIMS) and conventional dc magnetron sputtering (dcMS) while varying the angle between the target and the substrate surface from 0° (on-axis growth) to 90° (off-axis growth). Surface morphology and structural characterization were carried out using X-ray diffraction and reflection methods and the film properties were compared. The dcMS process shows higher growth rate than the HiPIMS process for on-axis grown films but the dcMS growth rate drops drastically for off-axis growth while the HiPIMS growth rate decreases slowly with increased angle between target and substrate for off-axis growth and becomes comparable to the dcMS growth rate. The dcMS grown films exhibit angle dependence in the density and surface roughness while the HiPIMS process creates denser and smoother films that are less angle dependent in all aspects. It was observed that the HiPIMS grown films remain poly-crystalline for all angles of rotation while the dcMS grown films are somewhat amorphous after 60°. The [111] and [200] grain sizes are comparable to the total film thickness in the HiPIMS grown films for all angles of rotation. In the case of dcMS, the [111], [200] and [220] grain sizes are roughly of the same size and much smaller than the total thickness for all growth angles except at 60° and higher. - Highlights: • TiN films were grown on SiO{sub 2} by HiPIMS and dcMS under various growth angles. • Influence of growth angle α = 0–90° on deposition rate and film quality was studied. • The HiPIMS process produces denser and smoother films for all growth angles. • At α = 0°, the growth rate of HiPIMS is 25% of dcMS while it is 50% at 90°. • The HiPIMS grown films remain poly-crystalline for all growth angles.

Thickness evaluation using a new relationship between film density and penetrated thickness in radiography

International Nuclear Information System (INIS)

Lee, Sung Sik; Kim, Young H.

2005-01-01

In order to improve the accuracies in the thickness evaluation using radiography, a new relationship between film density and penetrated thickness has been proposed, and experimental verification of the proposed relationship was carried out by using the X- and γ-ray radiographs of two carbon steel step wedges. A new parameter, the logarithmic gradient of film density, was defined in order to express the characteristics of the radiographic film for wider range of film density. A new relationship between the film density and the penetrated thickness were formulated using the logarithmic gradient of the film density. In experiment, the logarithmic gradient of the film density was independent on both the exposure and the film density and measured for the radiographic film used in the present work from the slope of the fitting lines for the same penetrated thickness. Experimental results verifies the accuracy of the proposed relationship between film density and the penetrated thickness for the range of film density from 1.0 to 3.5. The thickness can be more accurately determined by using the proposed relationship and the parameters determined by experiment. It is also found that the γ-ray having simple energy spectrum is more appropriate radiation source for the evaluation of the thickness from the film density of the radiograph

Effect of thickness on the structural and optical properties of CuO thin films grown by successive ionic layer adsorption and reaction

Energy Technology Data Exchange (ETDEWEB)

Akaltun, Yunus, E-mail: yakaltun@erzincan.edu.tr

2015-11-02

CuO thin films were synthesised on glass substrates at room temperature using successive ionic layer adsorption and reaction (SILAR) method. The effect of film thickness on characteristic parameters such as the structural, morphological and optical properties of the films was investigated. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies showed that all of the films exhibited polycrystalline structure with monoclinic phases and covered the glass substrates well. The crystalline and morphology of the films improved with increasing film thickness. The optical band gap decreased from 2.03 to 1.79 eV depending on the film thickness. The refractive index (n), electron effective mass (m{sub e}{sup ⁎}/m{sub o}) and static and frequency dielectric constants (ε{sub o}, ε{sub ∞}) were determined using the energy band gap values. - Highlights: • CuO thin films were deposited using SILAR method. • The electron effective mass, refractive index, dielectric constant values were calculated. • Characterisation of the films has been performed using XRD, SEM, Raman and optical measurements. • The d values of the planes of with thickness show no variation.

Characterization of interference thin films grown on stainless steel surface by alternate pulse current in a sulphochromic solution

Directory of Open Access Journals (Sweden)

Rosa Maria Rabelo Junqueira

2008-12-01

Full Text Available The aim of this work was to characterize thin interference films grown on the surface of AISI 304 stainless steel for decorative purposes. Films were grown in a sulphochromic solution at room temperature by an alternating pulse current method. The morphology and chemical state of the elements in the films were investigated by field emission scanning electron microscopy (FESEM, atomic force microscopy (AFM, glow discharge optical emission spectrometry (GDOES, and infrared Fourier transform spectroscopy (FTIR. Depth-sensing indentation (DSI experiments and wear abrasion tests were employed to assess the mechanical resistance of the films. The coloration process resulted in porous thin films which increased the surface roughness of the substrate. The interference films mainly consisted of hydrated chromium oxide containing iron. Increasing film thickness produced different colors and affected the mechanical properties of the coating-substrate system. Thicker films, such as those producing gold and green colors, were softer but more abrasion resistant.

Thickness-dependent blue shift in the excitonic peak of conformally grown ZnO:Al on ion-beam fabricated self-organized Si ripples

Energy Technology Data Exchange (ETDEWEB)

Basu, T.; Kumar, M.; Som, T., E-mail: tsom@iopb.res.in [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India); Nandy, S. [CENIMAT, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, Caparica 2829 516 (Portugal); Satpati, B. [Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, Kolkata 700 064 (India); Saini, C. P.; Kanjilal, A. [Department of Physics, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar, Uttar Pradesh 201 314 (India)

2015-09-14

Al-doped ZnO (AZO) thin films of thicknesses 5,10, 15, 20, and 30 nm were deposited on 500 eV argon ion-beam fabricated nanoscale self-organized rippled-Si substrates at room temperature and are compared with similar films deposited on pristine-Si substrates (without ripples). It is observed that morphology of self-organized AZO films is driven by the underlying substrate morphology. For instance, for pristine-Si substrates, a granular morphology evolves for all AZO films. On the other hand, for rippled-Si substrates, morphologies having chain-like arrangement (anisotropic in nature) are observed up to a thickness of 20 nm, while a granular morphology evolves (isotropic in nature) for 30 nm-thick film. Photoluminescence studies reveal that excitonic peaks corresponding to 5–15 nm-thick AZO films, grown on rippled-Si templates, show a blue shift of 8 nm and 3 nm, respectively, whereas the peak shift is negligible for 20-nm thick film (with respect to their pristine counter parts). The observed blue shifts are substantiated by diffuse reflectance study and attributed to quantum confinement effect, associated with the size of the AZO grains and their spatial arrangements driven by the anisotropic morphology of underlying rippled-Si templates. The present findings will be useful for making tunable AZO-based light-emitting devices.

Thick-film analysis: literature search and bibliography

International Nuclear Information System (INIS)

Gehman, R.W.

1981-09-01

A literature search was conducted to support development of in-house diagnostic testing of thick film materials for hybrid microcircuits. A background literature review covered thick film formulation, processing, structure, and performance. Important material properties and tests were identified and several test procedures were obtained. Several tests were selected for thick film diagnosis at Bendix Kansas City. 126 references

Enhanced off-resonance magnetoelectric response in laser annealed PZT thick film grown on magnetostrictive amorphous metal substrate

Energy Technology Data Exchange (ETDEWEB)

Palneedi, Haribabu [Materials Interface Laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of); Functional Ceramics Group, Korea Institute of Materials Science (KIMS), Changwon 641-831 (Korea, Republic of); Maurya, Deepam; Priya, Shashank [Bio-inspired Materials and Devices Laboratory (BMDL), Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Kim, Gi-Yeop; Choi, Si-Young, E-mail: youngchoi@kims.re.kr [Materials Modeling and Characterization Department, Korea Institute of Materials Science (KIMS), Changwon 641-831 (Korea, Republic of); Kang, Suk-Joong L. [Materials Interface Laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of); Kim, Kwang-Ho [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Ryu, Jungho, E-mail: jhryu@kims.re.kr [Functional Ceramics Group, Korea Institute of Materials Science (KIMS), Changwon 641-831 (Korea, Republic of)

2015-07-06

A highly dense, 4 μm-thick Pb(Zr,Ti)O{sub 3} (PZT) film is deposited on amorphous magnetostrictive Metglas foil (FeBSi) by granule spray in vacuum process at room temperature, followed by its localized annealing with a continuous-wave 560 nm ytterbium fiber laser radiation. This longer-wavelength laser radiation is able to anneal the whole of thick PZT film layer without any deteriorative effects, such as chemical reaction and/or atomic diffusion, at the interface and crystallization of amorphous Metglas substrate. Greatly enhanced dielectric and ferroelectric properties of the annealed PZT are attributed to its better crystallinity and grain growth induced by laser irradiation. As a result, a colossal off-resonance magnetoelectric (ME) voltage coefficient that is two orders of magnitude larger than previously reported output from PZT/Metglas film-composites is achieved. The present work addresses the problems involved in the fabrication of PZT/Metglas film-composites and opens up emerging possibilities in employing piezoelectric materials with low thermal budget substrates (suitable for integrated electronics) and designing laminate composites for ME based devices.

Thermal characterization of polycrystalline diamond thin film heat spreaders grown on GaN HEMTs

Science.gov (United States)

Zhou, Yan; Ramaneti, Rajesh; Anaya, Julian; Korneychuk, Svetlana; Derluyn, Joff; Sun, Huarui; Pomeroy, James; Verbeeck, Johan; Haenen, Ken; Kuball, Martin

2017-07-01

Polycrystalline diamond (PCD) was grown onto high-k dielectric passivated AlGaN/GaN-on-Si high electron mobility transistor (HEMT) structures, with film thicknesses ranging from 155 to 1000 nm. Transient thermoreflectance results were combined with device thermal simulations to investigate the heat spreading benefit of the diamond layer. The observed thermal conductivity (κDia) of PCD films is one-to-two orders of magnitude lower than that of bulk PCD and exhibits a strong layer thickness dependence, which is attributed to the grain size evolution. The films exhibit a weak temperature dependence of κDia in the measured 25-225 °C range. Device simulation using the experimental κDia and thermal boundary resistance values predicts at best a 15% reduction in peak temperature when the source-drain opening of a passivated AlGaN/GaN-on-Si HEMT is overgrown with PCD.

Morphological and microstructural stability of N-polar InAlN thin films grown on free-standing GaN substrates by molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Hardy, Matthew T., E-mail: matthew.hardy.ctr@nrl.navy.mil; Storm, David F.; Downey, Brian P.; Katzer, D. Scott; Meyer, David J. [Electronics Science and Technology Division, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington DC 20375 (United States); McConkie, Thomas O.; Smith, David J. [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); Nepal, Neeraj [Sotera Defense Solutions, 2200 Defense Hwy Suite 405, Crofton, Maryland 21114 (United States)

2016-03-15

The sensitivity of the surface morphology and microstructure of N-polar-oriented InAlN to variations in composition, temperature, and layer thickness for thin films grown by plasma-assisted molecular beam epitaxy (PAMBE) has been investigated. Lateral compositional inhomogeneity is present in N-rich InAlN films grown at low temperature, and phase segregation is exacerbated with increasing InN fraction. A smooth, step-flow surface morphology and elimination of compositional inhomogeneity can be achieved at a growth temperature 50 °C above the onset of In evaporation (650 °C). A GaN/AlN/GaN/200-nm InAlN heterostructure had a sheet charge density of 1.7 × 10{sup 13 }cm{sup −2} and no degradation in mobility (1760 cm{sup 2}/V s) relative to 15-nm-thick InAlN layers. Demonstration of thick-barrier high-electron-mobility transistors with good direct-current characteristics shows that device quality, thick InAlN layers can be successfully grown by PAMBE.

Morphological and microstructural stability of N-polar InAlN thin films grown on free-standing GaN substrates by molecular beam epitaxy

International Nuclear Information System (INIS)

Hardy, Matthew T.; Storm, David F.; Downey, Brian P.; Katzer, D. Scott; Meyer, David J.; McConkie, Thomas O.; Smith, David J.; Nepal, Neeraj

2016-01-01

The sensitivity of the surface morphology and microstructure of N-polar-oriented InAlN to variations in composition, temperature, and layer thickness for thin films grown by plasma-assisted molecular beam epitaxy (PAMBE) has been investigated. Lateral compositional inhomogeneity is present in N-rich InAlN films grown at low temperature, and phase segregation is exacerbated with increasing InN fraction. A smooth, step-flow surface morphology and elimination of compositional inhomogeneity can be achieved at a growth temperature 50 °C above the onset of In evaporation (650 °C). A GaN/AlN/GaN/200-nm InAlN heterostructure had a sheet charge density of 1.7 × 10 13  cm −2 and no degradation in mobility (1760 cm 2 /V s) relative to 15-nm-thick InAlN layers. Demonstration of thick-barrier high-electron-mobility transistors with good direct-current characteristics shows that device quality, thick InAlN layers can be successfully grown by PAMBE

Investigation of the correlation between dielectric function, thickness and morphology of nano-granular ZnO very thin films

Energy Technology Data Exchange (ETDEWEB)

Gilliot, Mickaël, E-mail: mickael.gilliot@univ-reims.fr [Laboratoire d' Ingénierie et Sciences des Matériaux, Université de Reims Champagne-Ardenne (France); Hadjadj, Aomar [Laboratoire d' Ingénierie et Sciences des Matériaux, Université de Reims Champagne-Ardenne (France); Martin, Jérôme [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Université de Technologie de Troyes (France)

2015-12-31

Thin nano-granular ZnO layers were prepared using a sol–gel synthesis and spin-coating deposition process with a thickness ranging between 20 and 120 nm. The complex dielectric function (ϵ) of the ZnO film was determined from spectroscopic ellipsometry measurements. Up to a critical thickness close to 60 nm, the magnitude of both the real and the imaginary parts of ϵ rapidly increases and then slowly tends to values closer to the bulk ZnO material. This trend suggests a drastic change in the film porosity at both sides of this critical thickness, due to the pre-heating and post-crystallization processes, as confirmed by additional characterization of the structure and the morphology of the ZnO films. - Highlights: • c-Axis oriented ZnO thin films were grown with different morphological states. • The morphology and structures are controlled by controlling the thickness. • The optical properties are correlated to morphological evolution. • Two growth behaviors and property evolutions are identified around a critical thickness.

Influence of processing parameters on PZT thick films

International Nuclear Information System (INIS)

Huang, Oliver; Bandyopadhyay, Amit; Bose, Susmita

2005-01-01

We have studied influence of processing parameters on the microstructure and ferroelectric properties of lead zirconate titanate (PZT)-based thick films in the range of 5-25 μm. PZT and 2% La-doped PZT thick films were processed using a modified sol-gel process. In this process, PZT- and La-doped PZT powders were first prepared via sol-gel. These powders were calcined and then used with respective sols to form a slurry. Slurry composition was optimized to spin-coat thick films on platinized Si substrate (Si/SiO 2 /Ti/Pt). Spinning rate, acceleration and slurry deposition techniques were optimized to form thick films with uniform thickness and without any cracking. Increasing solids loading was found to enhance the surface smoothness of the film and decrease porosity. Films were tested for their electrical properties and ferroelectric fatigue response. The maximum polarization obtained was 40 μC/cm 2 at 250 kV/cm for PZT thick film and 30 μC/cm 2 at 450 kV/cm for La-doped PZT thick film. After 10 9 cycles of fatiguing at 35 kHz, La-doped PZT showed better resistance for ferroelectric fatigue compared with un-doped PZT films

Disorder in silicon films grown epitaxially at low temperature

International Nuclear Information System (INIS)

Schwarzkopf, J.; Selle, B.; Bohne, W.; Roehrich, J.; Sieber, I.; Fuhs, W.

2003-01-01

Homoepitaxial Si films were prepared by electron cyclotron resonance plasma enhanced chemical vapor deposition on Si(100) substrates at temperatures of 325-500 deg. C using H 2 , Ar, and SiH 4 as process gases. The gas composition, substrate temperature, and substrate bias voltage were systematically varied to study the breakdown of epitaxial growth. Information from ion beam techniques, like Rutherford backscattering and heavy-ion elastic recoil detection analysis, was combined with transmission and scanning electron micrographs to examine the transition from ordered to amorphous growth. The results suggest that the breakdown proceeds in two stages: (i) highly defective but still ordered growth with a defect density increasing with increasing film thickness and (ii) formation of conically shaped amorphous precipitates. The hydrogen content is found to be directly related to the degree of disorder which acts as sink for excessive hydrogen. Only in almost perfect epitaxially grown films is the hydrogen level low, and an exponential tail of the H concentration into the crystalline substrate is observed as a result of the diffusive transport of hydrogen

The Thickness Dependence of Optical Constants of Ultrathin Iron Films

International Nuclear Information System (INIS)

Gao Shang; Lian Jie; Wang Xiao; Li Ping; Sun Xiao-Fen; Li Qing-Hao

2013-01-01

Ultrathin iron films with different thicknesses from 7.1 to 51.7 nm are deposited by magnetron sputtering and covered by tantalum layers protecting them from being oxidized. These ultrathin iron films are studied by spectroscopic ellipsometry and transmittance measurement. An extra tantalum film is deposited under the same sputtering conditions and its optical constants and film thickness are obtained by a combination of ellipsometry and transmission measurement. After introducing these obtained optical constants and film thickness into the tantalum-iron film, the optical constants and film thicknesses of ultrathin iron films with different thicknesses are obtained. The results show that combining ellipsometry and transmission measurement improves the uniqueness of the obtained film thickness. The optical constants of ultrathin iron films depend strongly on film thicknesses. There is a broad absorption peak at about 370 nm and it shifts to 410 nm with film thickness decreasing

Physical properties of SnS thin films grown by hot wall deposition

International Nuclear Information System (INIS)

Gremenok, V.; Ivanov, V.; Bashkirov, S.; Unuchak, D.; Lazenka, V.; Bente, K.; Tashlykov, I.; Turovets, A.

2010-01-01

Full text : Recently, considerable effort has been invested to gain a better and deeper knowledge of structural and physical properties of metal chalcogenide semiconductors because of their potential application in electrical and photonic devices. Among them, tin sulphide (SnS) has attracted attention because of band gap of 1.3 eV and an absorption coefficient greater than 10 4 cm - 1. Additionally, by using tin sulfide compounds for photovoltaic devices, the production costs are decreased, because these materials are cheap and abundant in nature. For the sythesis of SnS thin films by hot wall deposition, SnS ingots were used as the source materials synthesized from high purity elements (99.999 percent). The thin films were grown onto glass at substrate temperatures between 220 and 380 degrees Celsium. The thickness of the films was in the range of 1.0 - 2.5 μm. The crystal structure and crystalline phases of the materials were studied by XRD using a Siemens D-5000 diffractometer with CuK α (λ = 1.5418 A) radiation. In order to consider instrumental error, the samples were coated by Si powder suspended in acetone. The composition and surface morphology of thin films were investigated by electron probe microanalysis (EPMA) using a CAMECA SX-100, a scanning electron microscope JEOL 6400 and an atomic force microscope (AFM, Model: NT 206), respectively. Depth profiling was performed by Auger electron spectroscopy (AES) using a Perkin Elmer Physical Electronics 590. The electrical resistivity was studied by van der Pauw four-probe technique using silver paste contact. The optical transmittance was carried out using a Varian Cary 50 UV - VIS spectrophotometer in the range 500 - 2000 nm. The as-grown films exhibited a composition with a Sn/S at. percent ratio of 1.06. The AES depth profiles revealed relatively uniform composition through the film thickness. The XRD analysis of the SnS films showed that they were monophase (JCPDS 39-0354), polycrystalline with

Ultra-Smooth ZnS Films Grown on Silicon via Pulsed Laser Deposition

Science.gov (United States)

Reidy, Christopher; Tate, Janet

2011-10-01

Ultra-smooth, high quality ZnS films were grown on (100) and (111) oriented Si wafers via pulsed laser deposition with a KrF excimer laser in UHV (10-9 Torr). The resultant films were examined with optical spectroscopy, electron diffraction, and electron probe microanalysis. The films have an rms roughness of ˜1.5 nm, and the film stoichiometry is approximately Zn:S :: 1:0.87. Additionally, each film exhibits an optical interference pattern which is not a function of probing location on the sample, indicating excellent film thickness uniformity. Motivation for high-quality ZnS films comes from a proposed experiment to measure carrier amplification via impact ionization at the boundary between a wide-gap and a narrow-gap semiconductor. If excited charge carriers in a sufficiently wide-gap harvester can be extracted into a narrow-gap host material, impact ionization may occur. We seek near-perfect interfaces between ZnS, with a direct gap between 3.3 and 3.7 eV, and Si, with an indirect gap of 1.1 eV.

Structural characterization of epitaxial LiFe_5O_8 thin films grown by chemical vapor deposition

International Nuclear Information System (INIS)

Loukya, B.; Negi, D.S.; Sahu, R.; Pachauri, N.; Gupta, A.; Datta, R.

2016-01-01

We report on detailed microstructural and atomic ordering characterization by transmission electron microscopy in epitaxial LiFe_5O_8 (LFO) thin films grown by chemical vapor deposition (CVD) on MgO (001) substrates. The experimental results of LFO thin films are compared with those for bulk LFO single crystal. Electron diffraction studies indicate weak long-range ordering in LFO (α-phase) thin films in comparison to bulk crystal where strong ordering is observed in optimally annealed samples. The degree of long-range ordering depends on the growth conditions and the thickness of the film. Annealing experiment along with diffraction study confirms the formation of α-Fe_2O_3 phase in some regions of the films. This suggests that under certain growth conditions γ-Fe_2O_3-like phase forms in some pockets in the as-grown LFO thin films that then convert to α-Fe_2O_3 on annealing. - Highlights: • Atomic ordering in LiFe_5O_8 bulk single crystal and epitaxial thin films. • Electron diffraction studies reveal different level of ordering in the system. • Formation of γ-Fe_2O_3 like phase has been observed.

Control of thickness uniformity and grain size in graphene films for transparent conductive electrodes

International Nuclear Information System (INIS)

Wu Wei; Yu Qingkai; Pei, Shin-Shem; Peng Peng; Bao Jiming; Liu Zhihong

2012-01-01

Large-scale and transferable graphene films grown on metal substrates by chemical vapor deposition (CVD) still hold great promise for future nanotechnology. To realize the promise, one of the key issues is to further improve the quality of graphene, e.g., uniform thickness, large grain size, and low defects. Here we grow graphene films on Cu foils by CVD at ambient pressure, and study the graphene nucleation and growth processes under different concentrations of carbon precursor. On the basis of the results, we develop a two-step ambient pressure CVD process to synthesize continuous single-layer graphene films with large grain size (up to hundreds of square micrometers). Scanning electron microscopy and Raman spectroscopy characterizations confirm the film thickness and uniformity. The transferred graphene films on cover glass slips show high electrical conductivity and high optical transmittance that make them suitable as transparent conductive electrodes. The growth mechanism of CVD graphene on Cu is also discussed, and a growth model has been proposed. Our results provide important guidance toward the synthesis of high quality uniform graphene films, and could offer a great driving force for graphene based applications. (paper)

Thickness Dependent on Photocatalytic Activity of Hematite Thin Films

Directory of Open Access Journals (Sweden)

Yen-Hua Chen

2012-01-01

Full Text Available Hematite (Fe2O3 thin films with different thicknesses are fabricated by the rf magnetron sputtering deposition. The effects of film thicknesses on the photocatalytic activity of hematite films have been investigated. Hematite films possess a polycrystalline hexagonal structure, and the band gap decreases with an increase of film thickness. Moreover, all hematite films exhibit good photocatalytic ability under visible-light irradiation; the photocatalytic activity of hematite films increases with the increasing film thickness. This is because the hematite film with a thicker thickness has a rougher surface, providing more reaction sites for photocatalysis. Another reason is a lower band gap of a hematite film would generate more electron-hole pairs under visible-light illumination to enhance photocatalytic efficiency. Experimental data are well fitted with Langmuir-Hinshelwood kinetic model. The photocatalytic rate constant of hematite films ranges from 0.052 to 0.068 min-1. This suggests that the hematite film is a superior photocatalyst under visible-light irradiation.

Unraveling the role of SiC or Si substrates in water vapor incorporation in SiO 2 films thermally grown using ion beam analyses

Science.gov (United States)

Corrêa, S. A.; Soares, G. V.; Radtke, C.; Stedile, F. C.

2012-02-01

The incorporation of water vapor in SiO 2 films thermally grown on 6H-SiC(0 0 0 1) and on Si (0 0 1) was investigated using nuclear reaction analyses. Water isotopically enriched in deuterium ( 2H or D) and in 18O was used. The dependence of incorporated D with the water annealing temperature and initial oxide thickness were inspected. The D amount in SiO 2/SiC structures increases continuously with temperature and with initial oxide thickness, being incorporated in the surface, bulk, and interface regions of SiO 2 films. However, in SiO 2/Si, D is observed mostly in near-surface regions of the oxide and no remarkable dependence with temperature or initial oxide thickness was observed. At any annealing temperature, oxygen from water vapor was incorporated in all depths of the oxide films grown on SiC, in contrast with the SiO 2/Si.

Film-thickness and composition dependence of epitaxial thin-film PZT-based

NARCIS (Netherlands)

Nguyen, Duc Minh; Dekkers, Jan M.; Vu, Hung Ngoc; Rijnders, Augustinus J.H.M.

2013-01-01

The transverse piezoelectric coefficient e31,f and mass-sensitivity were measured on piezoelectric cantilevers based on epitaxial PZT thin-films with film-thicknesses ranging from 100 to 2000 nm. The highest values of e31,f and mass-sensitivity were observed at a film thickness of 500–750 nm, while

Effects of thickness on the nanocrystalline structure and semiconductor-metal transition characteristics of vanadium dioxide thin films

International Nuclear Information System (INIS)

Luo, Zhenfei; Zhou, Xun; Yan, Dawei; Wang, Du; Li, Zeyu; Yang, Cunbang; Jiang, Yadong

2014-01-01

Nanocrystalline vanadium dioxide (VO 2 ) thin films were grown on glass substrates by using reactive direct current magnetron sputtering and in situ thermal treatments at low preparation temperatures (≤ 350 °C). The VO 2 thin films were characterized by grazing-incidence X-ray diffraction, field emission scanning electron microscope, transmission electron microscopy and spectroscopic ellipsometry (SE). The semiconductor-metal transition (SMT) characteristics of the films were investigated by four-point probe resistivity measurements and infrared spectrometer equipped with heating pads. The testing results showed that the crystal structure, morphology, grain size and semiconductor-metal transition temperature (T SMT ) significantly changed as the film thickness decreased. Multilayer structures were observed in the particles of thinner films whose average particle size is much larger than the film thickness and average VO 2 grain size. A competition mechanism between the suppression effect of decreased thickness and coalescence of nanograins was proposed to understand the film growth and the formation of multilayer structure. The value of T SMT was found to decrease as average VO 2 grain size became smaller, and SE results showed that small nanograin size significantly affected the electronic structure of VO 2 film. - Highlights: • Nanocrystalline vanadium dioxide thin films were prepared. • Multilayer structures were observed in the films with large particles. • The transition temperature of the film is correlated with its electronic structure

Effects of substrate temperature and Cu underlayer thickness on the formation of SmCo5(0001) epitaxial thin films

International Nuclear Information System (INIS)

Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki; Kirino, Fumiyoshi

2010-01-01

SmCo 5 (0001) epitaxial thin films were prepared on Cu(111) underlayers heteroepitaxially grown on Al 2 O 3 (0001) single-crystal substrates by molecular beam epitaxy. The effects of substrate temperature and Cu underlayer thickness on the crystallographic properties of SmCo 5 (0001) epitaxial films were investigated. The Cu atoms of underlayer diffuse into the SmCo 5 film and substitute the Co sites in SmCo 5 structure forming an alloy compound of Sm(Co,Cu) 5 . The ordered phase formation is enhanced with increasing the substrate temperature and with increasing the Cu underlayer thickness. The Cu atom diffusion into the SmCo 5 film is assisting the formation of Sm(Co,Cu) 5 ordered phase.

Film thickness determination by grazing incidence diffraction

Energy Technology Data Exchange (ETDEWEB)

Battiston, G A; Gerbasi, R [CNR, Padua (Italy). Istituto di Chimica e Tecnologie Inorganiche e dei Materiali Avanzati

1996-09-01

Thin films deposited via MOCVD (Metal Organic Chemical Vapour Deposition) are layers in the thickness range of a few manometers to about ten micrometers. An understanding of the physics and chemistry of films is necessary for a better comprehension of the phenomena involved in the film deposition procedure and its optimisation. Together with the crystalline phase a parameter that must be determined is the thickness of the layer. In this work the authors present a method for the measurement of the film thickness. This procedure, based on diffraction intensity absorption of the X-rays, both incident and diffracted in passing through the layers, resulted quite simple, rapid and non-destructive.

Film thickness determination by grazing incidence diffraction

International Nuclear Information System (INIS)

Battiston, G. A.; Gerbasi, R.

1996-01-01

Thin films deposited via MOCVD (Metal Organic Chemical Vapour Deposition) are layers in the thickness range of a few manometers to about ten micrometers. An understanding of the physics and chemistry of films is necessary for a better comprehension of the phenomena involved in the film deposition procedure and its optimisation. Together with the crystalline phase a parameter that must be determined is the thickness of the layer. In this work the authors present a method for the measurement of the film thickness. This procedure, based on diffraction intensity absorption of the X-rays, both incident and diffracted in passing through the layers, resulted quite simple, rapid and non-destructive

Microstructure of epitaxial YBa2Cu3O7-x thin films grown on LaAlO3 (001)

International Nuclear Information System (INIS)

Hsieh, Y.; Siegal, M.P.; Hull, R.; Phillips, J.M.

1990-01-01

We report a microstructural investigation of the epitaxial growth of YBa 2 Cu 3 O 7-x (YBCO) thin films on LaAlO 3 (001) substrates using transmission electron microscopy (TEM). Epitaxial films grow with two distinct modes: c epitaxy (YBCO) single crystal with the c (axis normal to the surface and a epitaxy (YBCO) single crystal with the c axis in the interfacial plane), where c epitaxy is the dominant mode grown in all samples 35--200 nm thick. In 35 nm YBCO films annealed at 850 degree C, 97±1% of the surface area is covered by c epitaxy with embedded anisotropic a-epitaxial grains. Quantitative analysis reveals the effect of film thickness and annealing temperature on the density, grain sizes, areal coverages, and anisotropic growth of a epitaxy

Thickness oscillations of the transport properties in n-type Bi{sub 2}Te{sub 3} topological insulator thin films

Energy Technology Data Exchange (ETDEWEB)

Rogacheva, E.I., E-mail: rogacheva@kpi.kharkov.ua [National Technical University “Kharkov Polytechnic Institute”, 21 Frunze Street, Kharkov 61002 (Ukraine); Budnik, A.V.; Sipatov, A.Yu.; Nashchekina, O.N. [National Technical University “Kharkov Polytechnic Institute”, 21 Frunze Street, Kharkov 61002 (Ukraine); Fedorov, A.G. [Institute for Single Crystals of NAS of Ukraine, 60 Lenin Prospect, Kharkov 61001 (Ukraine); Dresselhaus, M.S.; Tang, S. [Department of Electrical Engineering and Computer Science and Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States)

2015-11-02

The dependences of the electrical conductivity, Seebeck coefficient and Hall coefficient on the thickness (d = 20–155 nm) of the n-type thin films grown on the glass substrates by the thermal evaporation in vacuum of the n-type Bi{sub 2}Te{sub 3} topological insulator crystals have been measured. It has been established that these dependences have an oscillatory character with a substantial amplitude. The obtained results are interpreted in terms of quantum size effects, taking into account the peculiar properties of the surface layers of the Bi{sub 2}Te{sub 3} films connected with the topological insulator nature of the bismuth telluride. - Highlights: • The thickness dependences of Bi{sub 2}Te{sub 3} thin films kinetic coefficients were obtained. • The dependences have oscillatory character with a substantial undamped amplitude. • The oscillation period increases with decreasing film thickness. • The oscillations are attributed to electron confinement in the film growth direction. • It is suggested that topological surface layer affects quantum processes in films.

Thermoelectric properties of ZnSb films grown by MOCVD

Energy Technology Data Exchange (ETDEWEB)

Venkatasubramanian, R; Watko, E; Colpitts, T

1997-07-01

The thermoelectric properties of ZnSb films grown by metallorganic chemical vapor deposition (MOCVD) are reported. The growth conditions necessary to obtain stoichiometric ZnSb films and the effects of various growth parameters on the electrical conductivity and Seebeck coefficients of the films are described. The as-grown ZnSb films are p-type. It was observed that the thicker ZnSb films offer improved carrier mobilities and lower free-carrier concentration levels. The Seebeck coefficient of ZnSb films was found to rise rapidly at approximately 160 C. The thicker films, due to the lower doping levels, indicate higher Seebeck coefficients between 25 to 200 C. A short annealing of the ZnSb film at temperatures of {approximately}200 C results in reduced free-carrier level. Thermal conductivity measurements of ZnSb films using the 3-{omega} method are also presented.

Aluminum oxide film thickness and emittance

International Nuclear Information System (INIS)

Thomas, J.K.; Ondrejcin, R.S.

1991-11-01

Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55 degrees C) moderator for about a year. The average moderator temperature was assumed to be 30 degrees C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 μm ± 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 μm ± 11%. Total hemispherical emittance is predicted to be 0.69 at 96 degrees C, decreasing to 0.45 at 600 degrees C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values

n-VO{sub 2}/p-GaN based nitride–oxide heterostructure with various thickness of VO{sub 2} layer grown by MBE

Energy Technology Data Exchange (ETDEWEB)

Wang, Minhuan [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Bian, Jiming, E-mail: jmbian@dlut.edu.cn [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050, China (China); Sun, Hongjun; Liu, Weifeng [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Zhang, Yuzhi [Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050, China (China); Luo, Yingmin [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

2016-12-15

Graphical abstract: The significant influences of VO{sub 2} layer thickness on the structural, electrical and contact properties of the n-VO{sub 2}/p-GaN based nitride-oxide heterostructure were investigated systemically. - Highlights: • High quality VO{sub 2} films with precisely controlled thickness were grown on p-GaN/sapphire substrates by oxide molecular beam epitaxy (O-MBE). • A distinct reversible SMT phase transition was observed for the n-VO{sub 2}/p-GaN based nitride-oxide heterostructure. • The clear rectifying transport characteristics originated from the n-VO{sub 2}/p-GaN interface were demonstrated before and after SMT of the VO{sub 2} over layer. • The XPS analyses confirmed the valence state of V in VO{sub 2} films was principally composed of V{sup 4+} with trace amount of V{sup 5+}. • The design and modulation of the n-VO{sub 2}/p-GaN based heterostructure devices will benefit significantly from these achievements. - Abstract: High quality VO{sub 2} films with precisely controlled thickness were grown on p-GaN/sapphire substrates by oxide molecular beam epitaxy (O-MBE). Results indicated that a distinct reversible semiconductor-to-metal (SMT) phase transition was observed for all the samples in the temperature dependent electrical resistance measurement, and the influence of VO{sub 2} layer thickness on the SMT properties of the as-grown n-VO{sub 2}/p-GaN based nitride-oxide heterostructure was investigated. Meanwhile, the clear rectifying transport characteristics originated from the n-VO{sub 2}/p-GaN interface were demonstrated before and after SMT of the VO{sub 2} over layer, which were attributed to the p-n junction behavior and Schottky contact character, respectively. Moreover, the X-ray photoelectron spectroscopy (XPS) analyses confirmed the valence state of vanadium (V) in VO{sub 2} films was principally composed of V{sup 4+} with trace amount of V{sup 5+}. The design and modulation of the n-VO{sub 2}/p-GaN based heterostructure

Effects of thickness on the nanocrystalline structure and semiconductor-metal transition characteristics of vanadium dioxide thin films

Energy Technology Data Exchange (ETDEWEB)

Luo, Zhenfei, E-mail: zhfluo8@yahoo.com [Terahertz Research Center, China Academy of Engineering Physics, Mianyang Sichuan 621900 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang Sichuan 621900 (China); Zhou, Xun, E-mail: zx_zky@yahoo.com [Terahertz Research Center, China Academy of Engineering Physics, Mianyang Sichuan 621900 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang Sichuan 621900 (China); Yan, Dawei [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang Sichuan 621900 (China); Wang, Du; Li, Zeyu [Terahertz Research Center, China Academy of Engineering Physics, Mianyang Sichuan 621900 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang Sichuan 621900 (China); Yang, Cunbang [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang Sichuan 621900 (China); Jiang, Yadong [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

2014-01-01

Nanocrystalline vanadium dioxide (VO{sub 2}) thin films were grown on glass substrates by using reactive direct current magnetron sputtering and in situ thermal treatments at low preparation temperatures (≤ 350 °C). The VO{sub 2} thin films were characterized by grazing-incidence X-ray diffraction, field emission scanning electron microscope, transmission electron microscopy and spectroscopic ellipsometry (SE). The semiconductor-metal transition (SMT) characteristics of the films were investigated by four-point probe resistivity measurements and infrared spectrometer equipped with heating pads. The testing results showed that the crystal structure, morphology, grain size and semiconductor-metal transition temperature (T{sub SMT}) significantly changed as the film thickness decreased. Multilayer structures were observed in the particles of thinner films whose average particle size is much larger than the film thickness and average VO{sub 2} grain size. A competition mechanism between the suppression effect of decreased thickness and coalescence of nanograins was proposed to understand the film growth and the formation of multilayer structure. The value of T{sub SMT} was found to decrease as average VO{sub 2} grain size became smaller, and SE results showed that small nanograin size significantly affected the electronic structure of VO{sub 2} film. - Highlights: • Nanocrystalline vanadium dioxide thin films were prepared. • Multilayer structures were observed in the films with large particles. • The transition temperature of the film is correlated with its electronic structure.

Interferometric measurement of film thickness during bubble blowing

Science.gov (United States)

Wang, Z.; Mandracchia, B.; Ferraro, V.; Tammaro, D.; Di Maio, E.; Maffettone, P. L.; Ferraro, P.

2017-06-01

In this paper, we propose digital holography in transmission configuration as an effective method to measure the time-dependent thickness of polymeric films during bubble blowing. We designed a complete set of experiments to measure bubble thickness, including the evaluation of the refractive index of the polymer solution. We report the measurement of thickness distribution along the film during the bubble formation process until the bubble`s rupture. Based on those data, the variation range and variation trend of bubble film thickness are clearly measured during the process of expansion to fracture is indicated.

Model, prediction, and experimental verification of composition and thickness in continuous spread thin film combinatorial libraries grown by pulsed laser deposition

International Nuclear Information System (INIS)

Bassim, N. D.; Schenck, P. K.; Otani, M.; Oguchi, H.

2007-01-01

Pulsed laser deposition was used to grow continuous spread thin film libraries of continuously varying composition as a function of position on a substrate. The thickness of each component that contributes to a library can be empirically modeled to a bimodal cosine power distribution. We deposited ternary continuous spread thin film libraries from Al 2 O 3 , HfO 2 , and Y 2 O 3 targets, at two different background pressures of O 2 : 1.3 and 13.3 Pa. Prior to library deposition, we deposited single component calibration films at both pressures in order to measure and fit the thickness distribution. Following the deposition and fitting of the single component films, we predict both the compositional coverage and the thickness of the libraries. Then, we map the thickness of the continuous spread libraries using spectroscopic reflectometry and measure the composition of the libraries as a function of position using mapping wavelength-dispersive spectrometry (WDS). We then compare the compositional coverage of the libraries and observe that compositional coverage is enhanced in the case of 13.3 Pa library. Our models demonstrate linear correlation coefficients of 0.98 for 1.3 Pa and 0.98 for 13.3 Pa with the WDS

Role of dislocations and carrier concentration in limiting the electron mobility of InN films grown by plasma assisted molecular beam epitaxy

Science.gov (United States)

Tangi, Malleswararao; De, Arpan; Shivaprasad, S. M.

2018-01-01

We report the molecular beam epitaxy growth of device quality InN films on GaN epilayer and nano-wall network (NWN) templates deposited on c-sapphire by varying the film thickness up to 1 μm. The careful experiments are directed towards obtaining high mobility InN layers having a low band gap with improved crystal quality. The dislocation density is quantified by using high resolution X-ray diffraction rocking curve broadening values of symmetric and asymmetric reflections, respectively. We observe that the dislocation density of the InN films grown on GaN NWN is less than that of the films grown on the GaN epilayer. This is attributed to the nanoepitaxial lateral overlayer growth (ELOG) process, where the presence of voids at the interface of InN/GaN NWN prevents the propagation of dislocation lines into the InN epilayers, thereby causing less defects in the overgrown InN films. Thus, this new adaptation of the nano-ELOG growth process enables us to prepare InN layers with high electron mobility. The obtained electron mobility of 2121 cm2/Vs for 1 μm thick InN/GaN NWN is comparable with the literature values of similar thickness InN films. Furthermore, in order to understand the reasons that limit electron mobility, the charge neutrality condition is employed to study the variation of electron mobility as a function of dislocation density and carrier concentration. Overall, this study provides a route to attaining improved crystal quality and electronic properties of InN films.

NdFeB thick films prepared by tape casting

International Nuclear Information System (INIS)

Pawlowski, B.; Schwarzer, S.; Rahmig, A.; Toepfer, J.

2003-01-01

NdFeB films of thickness between 100 and 800 μm were prepared by tape casting of a slurry containing 84-95 wt% of commercial NdFeB powder (MQP-B, -Q and -S). After curing the flexible green tapes at 120 deg. C non-porous magnetic films are obtained. The remanence of the films is in the range of 350-450 mT and the coercivity is between 300 and 800 kA/m depending on the type of MQP powder used. The magnetic properties of the films are discussed in relation to film composition and type of magnetic material. For MEMS applications the thick films are magnetized with a multi-pole stripe pattern with 1 mm pole pitch. The induction at the surface of the films was measured with a Hall probe and compared to theoretical calculations. The results indicate that the films are completely magnetized regardless of the film thickness. Tape-casted NdFeB thick films are promising candidates for applications in micro-systems or actuators. Miniaturization of the magnet components is one of the key issues in the development of electromagnetic micro-systems, thus creating a need for replacement of small sintered magnets by magnetic thick film components. Other applications include encoders

Electron-diffraction and spectroscopical characterisation of ultrathin ZnS films grown by molecular beam epitaxy on GaP(0 0 1)

International Nuclear Information System (INIS)

Zhang, L.; Szargan, R.; Chasse, T.

2004-01-01

ZnS films were grown by molecular beam epitaxy employing a single compound effusion cell on GaP(0 0 1) substrate at different temperatures, and characterised by means of low energy electron diffraction, X-ray and ultra-violet photoelectron spectroscopy, angle-resolved ultra-violet photoelectron spectroscopy and X-ray emission spectroscopy. The GaP(0 0 1) substrate exhibits a (4x2) reconstruction after Ar ion sputtering and annealing at 370 deg. C. Crystal quality of the ZnS films depends on both film thickness and growth temperature. Thinner films grown at higher temperatures and thicker films grown at lower temperatures have better crystal quality. The layer-by-layer growth mode of the ZnS films at lower (25, 80 and 100 deg. C) temperatures changes to layer-by-layer-plus-island mode at higher temperatures (120, 150 and 180 deg. C). A chemical reaction takes place and is confined to the interface. The valence band offset of the ZnS-GaP heterojunction was determined to be 0.8±0.1 eV. Sulphur L 2,3 emission spectra of ZnS powder raw material and the epitaxial ZnS films display the same features, regardless of the existence of the Ga-S bonding in the film samples

Structural and electronic characterization of 355 nm laser-crystallized silicon: Interplay of film thickness and laser fluence

International Nuclear Information System (INIS)

Semler, Matthew R.; Swenson, Orven F.; Hoey, Justin M.; Guruvenket, Srinivasan; Gette, Cody R.; Hobbie, Erik K.

2014-01-01

We present a detailed study of the laser crystallization of amorphous silicon thin films as a function of laser fluence and film thickness. Silicon films grown through plasma-enhanced chemical vapor deposition were subjected to a Q-switched, diode-pumped solid-state laser operating at 355 nm. The crystallinity, morphology, and optical and electronic properties of the films are characterized through transmission and reflectance spectroscopy, resistivity measurements, Raman spectroscopy, X-ray diffraction, atomic force microscopy, and optical and scanning-electron microscopy. Our results reveal a unique surface morphology that strongly couples to the electronic characteristics of the films, with a minimum laser fluence at which the film properties are optimized. A simple scaling model is used to relate film morphology to conductivity in the laser-processed films

Improvement in electrical insulating properties of 10-nm-thick Al2O3 film grown on Al/TiN/Si substrate by remote plasma annealing at low temperatures

International Nuclear Information System (INIS)

Kim, Jihoon; Song, Jaewon; Kwon, Ohsung; Kim, Sungkeun; Hwang, Cheol Seong; Park, Sang-Hee'Ko; Yun, Sun Jin; Jeong, Jaehack; Hyun, Kwang Soo

2002-01-01

The electrical conduction properties of 10-nm-thick atomic-layer deposited Al 2 O 3 thin films with Al bottom and Pt top electrodes were characterized for use in field emission display. The as-deposited films, grown at 300 deg. C, exhibited such a high electrical leakage that their electrical properties could not be measured. However, post-treatment at 300 deg. C under a remote O 2 or H 2 O plasma for 30 min improved the insulating properties of the Al 2 O 3 films. However, the electrical conduction mechanism, particularly in the high field (>4 MV/cm) was not Fowler-Nordheim (F-N) tunneling but was influenced by space charge limited conduction implying that there were many traps inside the dielectric film or the electrode interfaces. Postannealing of the top electrode at 300 deg. C in an oxygen atmosphere resulted in a F-N conduction mechanism by removing the interfacial traps. The calculated barrier height at the Al/Al 2 O 3 interface from the F-N fitting of the current density versus voltage curves using the electron effective mass (m * ) of 0.5 m 0 was approximately 2.0 eV

Advantages of PZT thick film for MEMS sensors

DEFF Research Database (Denmark)

Hindrichsen, Christian Carstensen; Lou-Moller, R.; Hansen, K.

2010-01-01

For all MEMS devices a high coupling between the mechanical and electrical domain is desired. Figures of merit describing the coupling are important for comparing different piezoelectric materials. The existing figures of merit are discussed and a new figure of merit is introduced for a fair comp....... Improved figure of merit is reached in the piezoelectric PZT thick film, TF2100CIP, by using cold isostatic pressure in the PZT preparation process. The porosity of TF2100 is decreased 38%, hence, allowing an increase of charge sensitivity for MEMS sensors of 59%....... thin film and PZT thick film. It is shown that MEMS sensors with the PZT thick film TF2100 from InSensor A/S have potential for significant higher voltage sensitivities compared to PZT thin film base MEMS sensors when the total thickness of the MEMS cantilever, beam, bridge or membrane is high...

High resolution electron microscopy studies of interfaces between Al2O3 substrates and MBE grown Nb films

International Nuclear Information System (INIS)

Mayer, J.; Ruhle, M.; Dura, J.; Flynn, C.P.

1991-01-01

This paper reports on single crystal niobium films grown by Molecular Beam Epitaxy (MBE) on (001) S sapphire substrates. Cross-sectional specimens with thickness of 2 O 3 interface could be investigated by high resolution electron microscopy (HREM). The orientation relationship between the metal film and the ceramic substrate was verified by selected area diffraction: (111) Nb parallel (0001) S and [1 bar 10] Nb parallel [2 bar 1 bar 10] S . The atomistic structure of the interface was identified by HREM

Influence of layer thickness on the structure and the magnetic properties of Co/Pd epitaxial multilayer films

Energy Technology Data Exchange (ETDEWEB)

Tobari, Kousuke, E-mail: tobari@futamoto.elect.chuo-u.ac.jp [Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo 112-8551 (Japan); Ohtake, Mitsuru; Nagano, Katsumasa; Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo 112-8551 (Japan)

2012-03-15

Co/Pd epitaxial multilayer films were prepared on Pd(111){sub fcc} underlayers hetero-epitaxially grown on MgO(111){sub B1} single-crystal substrates at room temperature by ultra-high vacuum RF magnetron sputtering. In-situ reflection high energy electron diffraction shows that the in-plane lattice spacing of Co on Pd layer gradually decreases with increasing the Co layer thickness, whereas that of Pd on Co layer remains unchanged during the Pd layer formation. The CoPd alloy phase formation is observed around the Co/Pd interface. The atomic mixing is enhanced for thinner Co and Pd layers in multilayer structure. With decreasing the Co and the Pd layer thicknesses and increasing the repetition number of Co/Pd multilayer film, stronger perpendicular magnetic anisotropy is observed. The relationships between the film structure and the magnetic properties are discussed. - Highlights: Black-Right-Pointing-Pointer Epitaxial Co/Pd multilayer films are prepared on Pd(111){sub fcc} underlayers. Black-Right-Pointing-Pointer Lattice strain in Co layer and CoPd-alloy formation are noted around the interface. Black-Right-Pointing-Pointer Magnetic property dependence on layer thickness is reported.

Thermoelectric power of Bi and Bi{sub 1{minus}x}Sb{sub x} alloy thin films and superlattices grown by MBE

Energy Technology Data Exchange (ETDEWEB)

Cho, S; DiVenere, A; Wong, G K; Ketterson, J B; Meyer, J R; Hoffman, C A

1997-07-01

The authors have measured the thermoelectric power (TEP) of MBE-grown epitaxial Bi and Bi{sub 1{minus}x} alloy thin films and superlattices as a function of temperature in the range 20--300 K. They have observed that the TEP of a Bi thin film of 1 {micro}m thickness is in good agreement with the bulk single crystal value and that the TEPs for superlattices with 400 {angstrom} and 800 {angstrom} Bi well thicknesses are enhanced over the bulk values. For x = 0.072 and 0.088 in Bi{sub 1{minus}x}Sb{sub x} thin films showing semiconducting behavior, TEP enhancement was observed by a factor of two. However as Bi or Bi{sub 1{minus}x}Sb{sub x} well thickness decreases in superlattice geometry, the TEP decreases, which may be due to unintentional p-type doping.

Multiple High Voltage Pulse Stressing of Polymer Thick Film Resistors

Directory of Open Access Journals (Sweden)

Busi Rambabu

2014-01-01

Full Text Available The purpose of this paper is to study high voltage interactions in polymer thick film resistors, namely, polyvinyl chloride- (PVC- graphite thick film resistors, and their applications in universal trimming of these resistors. High voltages in the form of impulses for various pulse durations and with different amplitudes have been applied to polymer thick film resistors and we observed the variation of resistance of these resistors with high voltages. It has been found that the resistance of polymer thick film resistors decreases in the case of higher resistivity materials and the resistance of polymer thick film resistor increases in the case of lower resistivity materials when high voltage impulses are applied to them. It has been also found that multiple high voltage pulse (MHVP stressing can be used to trim the polymer thick film resistors either upwards or downwards.

Evolution of optical constants of silicon dioxide on silicon from ultrathin films to thick films

Energy Technology Data Exchange (ETDEWEB)

Cai Qingyuan; Zheng Yuxiang; Mao Penghui; Zhang Rongjun; Zhang Dongxu; Liu Minghui; Chen Liangyao, E-mail: yxzheng@fudan.edu.c [Key Laboratory of Micro and Nano Photonic Structures, Ministry of Education, Department of Optical Science and Engineering, Fudan University, Shanghai 200433 (China)

2010-11-10

A series of SiO{sub 2} films with thickness range 1-600 nm have been deposited on crystal silicon (c-Si) substrates by electron beam evaporation (EBE) method. Variable-angle spectroscopic ellipsometry (VASE) in combination with a two-film model (ambient-oxide-interlayer substrate) was used to determine the optical constants and thicknesses of the investigated films. The refractive indices of SiO{sub 2} films thicker than 60 nm are close to those of bulk SiO{sub 2}. For the thin films deposited at the rate of {approx}1.0 nm s{sup -1}, the refractive indices increase with decreasing thickness from {approx}60 to {approx}10 nm and then drop sharply with decreasing thickness below {approx}10 nm. However, for thin films deposited at the rates of {approx}0.4 and {approx}0.2 nm s{sup -1}, the refractive indices monotonically increase with decreasing thickness below 60 nm. The optical constants of the ultrathin film depend on the morphology of the film, the stress exerted on the film, as well as the stoichiometry of the oxide film.

Evolution of optical constants of silicon dioxide on silicon from ultrathin films to thick films

International Nuclear Information System (INIS)

Cai Qingyuan; Zheng Yuxiang; Mao Penghui; Zhang Rongjun; Zhang Dongxu; Liu Minghui; Chen Liangyao

2010-01-01

A series of SiO 2 films with thickness range 1-600 nm have been deposited on crystal silicon (c-Si) substrates by electron beam evaporation (EBE) method. Variable-angle spectroscopic ellipsometry (VASE) in combination with a two-film model (ambient-oxide-interlayer substrate) was used to determine the optical constants and thicknesses of the investigated films. The refractive indices of SiO 2 films thicker than 60 nm are close to those of bulk SiO 2 . For the thin films deposited at the rate of ∼1.0 nm s -1 , the refractive indices increase with decreasing thickness from ∼60 to ∼10 nm and then drop sharply with decreasing thickness below ∼10 nm. However, for thin films deposited at the rates of ∼0.4 and ∼0.2 nm s -1 , the refractive indices monotonically increase with decreasing thickness below 60 nm. The optical constants of the ultrathin film depend on the morphology of the film, the stress exerted on the film, as well as the stoichiometry of the oxide film.

Multiple delta doping of single crystal cubic boron nitride films heteroepitaxially grown on (001)diamonds

Science.gov (United States)

Yin, H.; Ziemann, P.

2014-06-01

Phase pure cubic boron nitride (c-BN) films have been epitaxially grown on (001) diamond substrates at 900 °C. The n-type doping of c-BN epitaxial films relies on the sequential growth of nominally undoped (p-) and Si doped (n-) layers with well-controlled thickness (down to several nanometer range) in the concept of multiple delta doping. The existence of nominally undoped c-BN overgrowth separates the Si doped layers, preventing Si dopant segregation that was observed for continuously doped epitaxial c-BN films. This strategy allows doping of c-BN films can be scaled up to multiple numbers of doped layers through atomic level control of the interface in the future electronic devices. Enhanced electronic transport properties with higher hall mobility (102 cm2/V s) have been demonstrated at room temperature as compared to the normally continuously Si doped c-BN films.

Residual carrier density in GaSb grown on Si substrates

International Nuclear Information System (INIS)

Akahane, Kouichi; Yamamoto, Naokatsu; Gozu, Shin-ichiro; Ueta, Akio; Ohtani, Naoki

2006-01-01

The relationships between the densities of residual carriers and those of dislocation in GaSb films grown on Si substrates were investigated. Dislocation density was evaluated by cross-sectional transmission electron microscopy (TEM). The TEM images indicated that the dislocation density after a 5-μm-thick GaSb film was grown was below 1 x 10 8 /cm 2 although the density near the interface between the Si substrate and the GaSb film was about 3 x 10 9 /cm 2 . Forming a dislocation loop by growing a thick GaSb layer may decrease the dislocation density. The density and mobility of the residual carrier were investigated by Hall measurement using the van der Pauw method. The residual carriers in GaSb grown on Si substrates were holes, and their densities decreased significantly from 4.2 x 10 18 to 1.4 x 10 17 /cm 3 as GaSb thickness was increased from 500 to 5500 nm

The effects of thermal annealing on the structure and the electrical transport properties of ultrathin gadolinia-doped ceria films grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Rodrigo, K.; Pryds, N.; Theil Kuhn, L.; Esposito, V.; Linderoth, S. [Technical University of Denmark, Fuel Cells and Solid State Chemistry Division, Risoe DTU, Roskilde (Denmark); Heiroth, S.; Lippert, T. [Paul Scherrer Institute, General Energy Research Department, Villigen PSI (Switzerland); Schou, J. [Technical University of Denmark, Department of Photonics Engineering, Roskilde (Denmark)

2011-09-15

Ultrathin crystalline films of 10 mol% gadolinia-doped ceria (CGO10) are grown on MgO (100) substrates by pulsed laser deposition at a moderate temperature of 400 C. As-deposited CGO10 layers of approximately 4 nm, 14 nm, and 22 nm thickness consist of fine grains with dimensions {<=}{proportional_to}11 nm. The films show high density within the thickness probed in the X-ray reflectivity experiments. Thermally activated grain growth, density decrease, and film surface roughening, which may result in the formation of incoherent CGO10 islands by dewetting below a critical film thickness, are observed upon heat treatment at 400 C and 800 C. The effect of the grain coarsening on the electrical characteristics of the layers is investigated and discussed in the context of a variation of the number density of grain boundaries. The results are evaluated with regard to the use of ultrathin CGO10 films as seeding templates for the moderate temperature growth of thick solid electrolyte films with improved oxygen transport properties. (orig.)

Thin Cu film resistivity using four probe techniques: Effect of film thickness and geometrical shapes

Science.gov (United States)

Choudhary, Sumita; Narula, Rahul; Gangopadhyay, Subhashis

2018-05-01

Precise measurement of electrical sheet resistance and resistivity of metallic thin Cu films may play a significant role in temperature sensing by means of resistivity changes which can further act as a safety measure of various electronic devices during their operation. Four point probes resistivity measurement is a useful approach as it successfully excludes the contact resistance between the probes and film surface of the sample. Although, the resistivity of bulk samples at a particular temperature mostly depends on its materialistic property, however, it may significantly differ in the case of thin films, where the shape and thickness of the sample can significantly influence on it. Depending on the ratio of the film thickness to probe spacing, samples are usually classified in two segments such as (i) thick films or (ii) thin films. Accordingly, the geometric correction factors G can be related to the sample resistivity r, which has been calculated here for thin Cu films of thickness up to few 100 nm. In this study, various rectangular shapes of thin Cu films have been used to determine the shape induced geometric correction factors G. An expressions for G have been obtained as a function of film thickness t versus the probe spacing s. Using these expressions, the correction factors have been plotted separately for each cases as a function of (a) film thickness for fixed linear probe spacing and (b) probe distance from the edge of the film surface for particular thickness. Finally, we compare the experimental results of thin Cu films of various rectangular geometries with the theoretical reported results.

High resolution x-ray diffraction study of the substrate temperature and thickness dependent microstructure of reactively sputtered epitaxial ZnO films

KAUST Repository

Singh, Devendra

2017-08-24

Epitaxial ZnO films were grown on c-sapphire by reactive sputtering of zinc target in Ar-O2 mixture. High resolution X-ray diffraction measurements were carried out to obtain lateral and vertical coherence lengths, crystallite tilt and twist, micro-strain and densities of screw and edge dislocations in epilayers of different thickness (25 - 200 nm) and those grown at different temperatures (100 - 500 °C). phgr-scans indicate epitaxial growth in all the cases, although epilayers grown at lower substrate temperatures (100 °C and 200 °C) and those of smaller thickness (25 nm and 50 nm) display inferior microstructural parameters. This is attributed to the dominant presence of initially grown strained 2D layer and subsequent transition to an energetically favorable mode. With increase in substrate temperature, the transition shifts to lower thickness and growth takes place through the formation of 2D platelets with intermediate strain, over which 3D islands grow. Consequently, 100 nm thick epilayers grown at 300 °C display the best microstructural parameters (micro-strain ~1.2 x 10-3, screw and edge dislocation densities ~1.5 x 1010 cm-2 and ~2.3 x 1011 cm-2, respectively). A marginal degradation of microstructural parameters is seen in epilayers grown at higher substrate temperatures, due to the dominance of 3D hillock type growth.

High resolution x-ray diffraction study of the substrate temperature and thickness dependent microstructure of reactively sputtered epitaxial ZnO films

KAUST Repository

Singh, Devendra; Kumar, Ravi; Ganguli, Tapas; Major, Syed S

2017-01-01

Epitaxial ZnO films were grown on c-sapphire by reactive sputtering of zinc target in Ar-O2 mixture. High resolution X-ray diffraction measurements were carried out to obtain lateral and vertical coherence lengths, crystallite tilt and twist, micro-strain and densities of screw and edge dislocations in epilayers of different thickness (25 - 200 nm) and those grown at different temperatures (100 - 500 °C). phgr-scans indicate epitaxial growth in all the cases, although epilayers grown at lower substrate temperatures (100 °C and 200 °C) and those of smaller thickness (25 nm and 50 nm) display inferior microstructural parameters. This is attributed to the dominant presence of initially grown strained 2D layer and subsequent transition to an energetically favorable mode. With increase in substrate temperature, the transition shifts to lower thickness and growth takes place through the formation of 2D platelets with intermediate strain, over which 3D islands grow. Consequently, 100 nm thick epilayers grown at 300 °C display the best microstructural parameters (micro-strain ~1.2 x 10-3, screw and edge dislocation densities ~1.5 x 1010 cm-2 and ~2.3 x 1011 cm-2, respectively). A marginal degradation of microstructural parameters is seen in epilayers grown at higher substrate temperatures, due to the dominance of 3D hillock type growth.

Thermal stability of amorphous carbon films grown by pulsed laser deposition

Science.gov (United States)

Friedmann, T. A.; McCarty, K. F.; Barbour, J. C.; Siegal, M. P.; Dibble, Dean C.

1996-03-01

The thermal stability in vacuum of amorphous tetrahedrally coordinated carbon (a-tC) films grown on Si has been assessed by in situ Raman spectroscopy. Films were grown in vacuum on room-temperature substrates using laser fluences of 12, 22, and 45 J/cm2 and in a background gas of either hydrogen or nitrogen using a laser fluence of 45 J/cm2. The films grown in vacuum at high fluence (≳20J/cm2) show little change in the a-tC Raman spectra with temperature up to 800 °C. Above this temperature the films convert to glassy carbon (nanocrystalline graphite). Samples grown in vacuum at lower fluence or in a background gas (H2 or N2) at high fluence are not nearly as stable. For all samples, the Raman signal from the Si substrate (observed through the a-tC film) decreases in intensity with annealing temperature indicating that the transparency of the a-tC films is decreasing with temperature. These changes in transparency begin at much lower temperatures (˜200 °C) than the changes in the a-tC Raman band shape and indicate that subtle changes are occurring in the a-tC films at lower temperatures.

Room temperature magnetism of few-nanometers-thick Fe{sub 3}O{sub 4}(111) films on Pt(111) and Ru(0001) studied in ambient conditions

Energy Technology Data Exchange (ETDEWEB)

Lewandowski, M., E-mail: lewandowski@amu.edu.pl [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Miłosz, Z.; Michalak, N.; Ranecki, R. [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Sveklo, I.; Kurant, Z.; Maziewski, A. [Faculty of Physics, University of Białystok, Lipowa 41, 15-424 Białystok (Poland); Mielcarek, S. [Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Luciński, T. [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Jurga, S. [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland)

2015-09-30

Few-nanometers-thick Fe{sub 3}O{sub 4}(111) films were epitaxially grown on Pt(111) and Ru(0001) single crystal supports by sequential iron deposition and oxidation in an ultra-high vacuum chamber. The growth of well-ordered magnetite films was confirmed by low energy electron diffraction. The films were covered with a protective Au layer and subjected to magnetic and structural studies in ambient conditions. Magnetic hysteresis loops, recorded using magneto-optical Kerr effect apparatus, confirmed magnetic ordering in both films at room temperature. The Kerr measurements indicated in-plane orientation of magnetization, which was supported by the lack of magnetic contrast in magnetic force microscopy images. Atomic force microscopy revealed significant differences in morphology of the films, tentatively attributed to different lattice mismatch with Pt(111) and Ru(0001) single crystal supports. - Highlights: • Few-nanometers-thick Fe{sub 3}O{sub 4}(111) films were grown on Pt(111) and Ru(0001). • Magnetic properties were studied using MOKE and AFM/MFM in ambient conditions. • The films exhibited in-plane magnetic ordering at room temperature. • Differences in magnetic properties were tentatively assigned to structural differences.

Electrical properties of ZnO thin films grown by MOCVD

Energy Technology Data Exchange (ETDEWEB)

Pagni, O. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Somhlahlo, N.N. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Weichsel, C. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Leitch, A.W.R. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa)]. E-mail: andrew.leitch@nmmu.ac.za

2006-04-01

We report on the electrical characterization of ZnO films grown by MOCVD on glass and sapphire substrates. After correcting our temperature variable Hall measurements by applying the standard two-layer model, which takes into account an interfacial layer, scattering mechanisms in the ZnO films were studied as well as donor activation energies determined. ZnO films grown at different oxygen partial pressures indicated the importance of growth conditions on the defect structure by means of their conductivities and conductivity activation energies.

Electrical properties of ZnO thin films grown by MOCVD

International Nuclear Information System (INIS)

Pagni, O.; Somhlahlo, N.N.; Weichsel, C.; Leitch, A.W.R.

2006-01-01

We report on the electrical characterization of ZnO films grown by MOCVD on glass and sapphire substrates. After correcting our temperature variable Hall measurements by applying the standard two-layer model, which takes into account an interfacial layer, scattering mechanisms in the ZnO films were studied as well as donor activation energies determined. ZnO films grown at different oxygen partial pressures indicated the importance of growth conditions on the defect structure by means of their conductivities and conductivity activation energies

Influence of thickness on properties of plasticized oat starch films

Directory of Open Access Journals (Sweden)

Melicia Cintia Galdeano

2013-08-01

Full Text Available The aim of this study was to investigate the effect of thickness (between 80 and 120 µm on apparent opacity, water vapor permeability and mechanical properties (tensile and puncture of oat starch films plasticized with glycerol, sorbitol, glycerol:sorbitol mixture, urea and sucrose. Films were stored under 11, 57, 76 and 90% relative humidity (RH to study the mechanical properties. It was observed that the higher the thickness, the higher was the opacity values. Films without the plasticizer were more opaque in comparison with the plasticized ones. Glycerol:sorbitol films presented increased elongation with increasing thickness at all RH. Puncture force showed a strong dependence on the film thickness, except for the films plasticized with sucrose. In general, thickness did not affect the water permeability.

Film thickness in gas-liquid two-phase flow, (2)

International Nuclear Information System (INIS)

Sekoguchi, Kotohiko; Fukano, Toru; Kawakami, Yasushi; Shimizu, Hideo.

1977-01-01

The effect of four rectangular obstacles inserted into a circular tube has been studied in gas-liquid two-phase flow. The obstacles are set on the inner wall of the tube, and the ratio of the opening is 0.6. The water film flows partially through the obstacles. The minimum thickness of water film was measured in relation to flow speed. The serious effect of the obstacles was seen against the formation of water film, and drainage under the obstacles and backward flow play important roles. Since water film can flow partially through the obstacles, the film in case of the rectangular obstacles in thicker than that in case of an orifice when the gas flow speed was slower than 5 m/s. However, when the gas flow speed is over 5 m/s, the film thickness was thinner. The minimum film thickness of downstream of the obstacles was almost same as that in case of no obstacle. The minimum film thickness of up stream depends on the location of measurement due to the effect of drainage. (Kato, T.)

One-step aerosol synthesis of nanoparticle agglomerate films: simulation of film porosity and thickness

International Nuclear Information System (INIS)

Maedler, Lutz; Lall, Anshuman A; Friedlander, Sheldon K

2006-01-01

A method is described for designing nanoparticle agglomerate films with desired film porosity and film thickness. Nanoparticle agglomerates generated in aerosol reactors can be directly deposited on substrates to form uniform porous films in one step, a significant advance over existing technologies. The effect of agglomerate morphology and deposition mechanism on film porosity and thickness are discussed. Film porosity was calculated for a given number and size of primary particles that compose the agglomerates, and fractal dimension. Agglomerate transport was described by the Langevin equation of motion. Deposition enhancing forces such as thermophoresis are incorporated in the model. The method was validated for single spherical particles using previous theoretical studies. An S-shape film porosity dependence on the particle Peclet number typical for spherical particles was also observed for agglomerates, but films formed from agglomerates had much higher porosities than films from spherical particles. Predicted film porosities compared well with measurements reported in the literature. Film porosities increased with the number of primary particles that compose an agglomerate and higher fractal dimension agglomerates resulted in denser films. Film thickness as a function of agglomerate deposition time was calculated from the agglomerate deposition flux in the presence of thermophoresis. The calculated film thickness was in good agreement with measured literature values. Thermophoresis can be used to reduce deposition time without affecting the film porosity

Atomically flat platinum films grown on synthetic mica

Science.gov (United States)

Tanaka, Hiroyuki; Taniguchi, Masateru

2018-04-01

Atomically flat platinum thin films were heteroepitaxially grown on synthetic fluorophlogopite mica [KMg3(AlSi3O10)F2] by van der Waals epitaxy. Platinum films deposited on a fluorophlogopite mica substrate by inductively coupled plasma-assisted sputtering with oxygen introduction on a synthetic mica substrate resulted in the growth of twin single-crystalline epitaxial Pt(111) films.

Barium titanate thick films prepared by screen printing technique

Directory of Open Access Journals (Sweden)

Mirjana M. Vijatović

2010-06-01

Full Text Available The barium titanate (BaTiO3 thick films were prepared by screen printing technique using powders obtained by soft chemical route, modified Pechini process. Three different barium titanate powders were prepared: i pure, ii doped with lanthanum and iii doped with antimony. Pastes for screen printing were prepared using previously obtained powders. The thick films were deposited onto Al2O3 substrates and fired at 850°C together with electrode material (silver/palladium in the moving belt furnace in the air atmosphere. Measurements of thickness and roughness of barium titanate thick films were performed. The electrical properties of thick films such as dielectric constant, dielectric losses, Curie temperature, hysteresis loop were reported. The influence of different factors on electrical properties values was analyzed.

Temperature- and thickness-dependent elastic moduli of polymer thin films

Directory of Open Access Journals (Sweden)

Ao Zhimin

2011-01-01

Full Text Available Abstract The mechanical properties of polymer ultrathin films are usually different from those of their counterparts in bulk. Understanding the effect of thickness on the mechanical properties of these films is crucial for their applications. However, it is a great challenge to measure their elastic modulus experimentally with in situ heating. In this study, a thermodynamic model for temperature- (T and thickness (h-dependent elastic moduli of polymer thin films Ef(T,h is developed with verification by the reported experimental data on polystyrene (PS thin films. For the PS thin films on a passivated substrate, Ef(T,h decreases with the decreasing film thickness, when h is less than 60 nm at ambient temperature. However, the onset thickness (h*, at which thickness Ef(T,h deviates from the bulk value, can be modulated by T. h* becomes larger at higher T because of the depression of the quenching depth, which determines the thickness of the surface layer δ.

Influence of Thickness on Ethanol Sensing Characteristics of Doctor-bladed Thick Film from Flame-made ZnO Nanoparticles

Directory of Open Access Journals (Sweden)

Sukon Phanichphant

2007-02-01

Full Text Available ZnO nanoparticles were produced by flame spray pyrolysis (FSP using zincnaphthenate as a precursor dissolved in toluene/acetonitrile (80/20 vol%. The particleproperties were analyzed by XRD, BET, and HR-TEM. The sensing films were produced bymixing the particles into an organic paste composed of terpineol and ethyl cellulose as avehicle binder and were fabricated by doctor-blade technique with various thicknesses (5,10, 15 μm. The morphology of the sensing films was analyzed by SEM and EDS analyses.The gas sensing characteristics to ethanol (25-250 ppm were evaluated as a function of filmthickness at 400°C in dry air. The relationship between thickness and ethanol sensingcharacteristics of ZnO thick film on Al2O3 substrate interdigitated with Au electrodes wereinvestigated. The effects of film thickness, as well as the cracking phenomenon, though,many cracks were observed for thicker sensing films. Crack widths increased withincreasing film thickness. The film thickness, cracking and ethanol concentration havesignificant effect on the sensing characteristics. The sensing characteristics with variousthicknesses were compared, showing the tendency of the sensitivity to ethanol decreasedwith increasing film thickness and response time. The relationship between gas sensingproperties and film thickness was discussed on the basis of diffusively and reactivity of thegases inside the oxide films. The thinnest sensing film (5 μm showed the highest sensitivityand the fastest response time (within seconds.

Magnetic anisotropies in ultrathin bismuth iron garnet films

International Nuclear Information System (INIS)

Popova, Elena; Franco Galeano, Andres Felipe; Deb, Marwan; Warot-Fonrose, Bénédicte; Kachkachi, Hamid; Gendron, François; Ott, Frédéric

2013-01-01

Ultrathin bismuth iron garnet Bi 3 Fe 5 O 12 films were grown epitaxially on (001)-oriented gadolinium gallium garnet substrates. Film thickness varied from two to three dozens of unit cells. Bi 3 Fe 5 O 12 films grow pseudomorphically on substrates up to a thickness of 20 nm, and then a lattice relaxation occurs. Magnetic properties of the films were studied as a function of bismuth iron garnet thickness. The magnetization and cubic anisotropy decrease with decreasing film thickness. The uniaxial magnetocrystalline anisotropy is constant for all film thicknesses. For two unit cell thick films, the easy magnetization axis changes from in-plane to perpendicular to the plane direction. Such a reorientation takes place as a result of the competition of constant uniaxial perpendicular anisotropy with weakening film magnetization. - Highlights: ► Ultrathin Bi 3 Fe 5 O 12 films were grown epitaxially on structure-matching substrates. ► Magnetic properties of Bi 3 Fe 5 O 12 were studied down to the thickness of 2.5 nm. ► Reorientation of easy magnetization axis as a function of film thickness was observed

Magnetic anisotropies in ultrathin bismuth iron garnet films

Energy Technology Data Exchange (ETDEWEB)

Popova, Elena, E-mail: popova@physique.uvsq.fr [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS/Université de Versailles-Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles (France); Franco Galeano, Andres Felipe [Laboratoire PROcédés, Matériaux et Energie Solaire (PROMES), CNRS/Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan (France); Deb, Marwan [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS/Université de Versailles-Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles (France); Warot-Fonrose, Bénédicte [Centre d' Elaboration de Matériaux et d' Etudes Structurales (CEMES), CNRS, 29 rue Jeanne Marvig, 31055 Toulouse (France); Transpyrenean Associated Laboratory for Electron Microscopy (TALEM), CEMES-INA, CNRS–Universidad de Zaragoza (Spain); Kachkachi, Hamid [Laboratoire PROcédés, Matériaux et Energie Solaire (PROMES), CNRS/Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan (France); Gendron, François [Institut des NanoSciences de Paris (INSP), CNRS/Université Pierre et Marie Curie-Paris 6, 4 place Jussieu, Boîte courrier 840, 75252 Paris Cedex 05 (France); Ott, Frédéric [Laboratoire Léon Brillouin (LLB), CNRS/CEA, Bâtiment 563, CEA Saclay, 91191 Gif sur Yvette Cedex (France); and others

2013-06-15

Ultrathin bismuth iron garnet Bi{sub 3}Fe{sub 5}O{sub 12} films were grown epitaxially on (001)-oriented gadolinium gallium garnet substrates. Film thickness varied from two to three dozens of unit cells. Bi{sub 3}Fe{sub 5}O{sub 12} films grow pseudomorphically on substrates up to a thickness of 20 nm, and then a lattice relaxation occurs. Magnetic properties of the films were studied as a function of bismuth iron garnet thickness. The magnetization and cubic anisotropy decrease with decreasing film thickness. The uniaxial magnetocrystalline anisotropy is constant for all film thicknesses. For two unit cell thick films, the easy magnetization axis changes from in-plane to perpendicular to the plane direction. Such a reorientation takes place as a result of the competition of constant uniaxial perpendicular anisotropy with weakening film magnetization. - Highlights: ► Ultrathin Bi{sub 3}Fe{sub 5}O{sub 12} films were grown epitaxially on structure-matching substrates. ► Magnetic properties of Bi{sub 3}Fe{sub 5}O{sub 12} were studied down to the thickness of 2.5 nm. ► Reorientation of easy magnetization axis as a function of film thickness was observed.

Quantum confinement effect in Bi anti-dot thin films with tailored pore wall widths and thicknesses

International Nuclear Information System (INIS)

Park, Y.; Hirose, Y.; Fukumura, T.; Hasegawa, T.; Nakao, S.; Xu, J.

2014-01-01

We investigated quantum confinement effects in Bi anti-dot thin films grown on anodized aluminium oxide templates. The pore wall widths (w Bi ) and thickness (t) of the films were tailored to have values longer or shorter than Fermi wavelength of Bi (λ F  = ∼40 nm). Magnetoresistance measurements revealed a well-defined weak antilocalization effect below 10 K. Coherence lengths (L ϕ ) as functions of temperature were derived from the magnetoresistance vs field curves by assuming the Hikami-Larkin-Nagaoka model. The anti-dot thin film with w Bi and t smaller than λ F showed low dimensional electronic behavior at low temperatures where L ϕ (T) exceed w Bi or t

Thickness-dependent spontaneous dewetting morphology of ultrathin Ag films

Energy Technology Data Exchange (ETDEWEB)

Krishna, H; Favazza, C [Department of Physics, Washington University in St Louis, MO 63130 (United States); Sachan, R; Strader, J; Kalyanaraman, R [Department of Material Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Khenner, M, E-mail: ramki@utk.edu [Department of Mathematics, Western Kentucky University, Bowling Green, KY 42101 (United States)

2010-04-16

We show here that the morphological pathway of spontaneous dewetting of ultrathin Ag films on SiO{sub 2} under nanosecond laser melting is dependent on film thickness. For films with thickness h of 2 nm {<=} h {<=} 9.5 nm, the morphology during the intermediate stages of dewetting consisted of bicontinuous structures. For films with 11.5 nm {<=} h {<=} 20 nm, the intermediate stages consisted of regularly sized holes. Measurement of the characteristic length scales for different stages of dewetting as a function of film thickness showed a systematic increase, which is consistent with the spinodal dewetting instability over the entire thickness range investigated. This change in morphology with thickness is consistent with observations made previously for polymer films (Sharma and Khanna 1998 Phys. Rev. Lett. 81 3463-6; Seemann et al 2001 J. Phys.: Condens. Matter 13 4925-38). Based on the behavior of free energy curvature that incorporates intermolecular forces, we have estimated the morphological transition thickness for the intermolecular forces for Ag on SiO{sub 2}. The theory predictions agree well with observations for Ag. These results show that it is possible to form a variety of complex Ag nanomorphologies in a consistent manner, which could be useful in optical applications of Ag surfaces, such as in surface enhanced Raman sensing.

A new attempt of measurement film thickness by x-ray diffractometry

International Nuclear Information System (INIS)

Kosaka, Masao; Kobayashi, Hideo

1987-01-01

In order to make film thickness measurements independent from the property or the structure of the film materials or the substrate, it is needed to adopt instead of directly utilizing the X-ray diffraction intensity, or attenuation information obtained from the substrate or film material, other new methods for measurement. Among the information obtained by X-ray diffraction, if intensity is excluded, others are F.W.H.M. and diffraction angle, only. If it is possible to investigate the film thickness dependency of the diffraction angle, it should be possible to measure the film thickness by diffraction angle. However, since diffraction angle has no film thickness dependency, it cannot be used directly for measurement. However, if we consider the principle of the X-ray diffractometer method, although it may be very slight, the substrate will be eccentric from the revolving center of the goniometer on account of the thickness of the film. If eccentricity occurs, this will cause changes in the diffraction angle. If we set the radius of the goniometer as R, diffraction angle θ, and the eccentricity from the revolving center of the specimen surface X, the deflection angle Δ2θ of 2θ may be expressed by Δ2θ = -2X · COSθ/R Thus, if X is caused by the film thickness, and by measuring the Δ2θ, it will be possible to measure the film thickness. As a result of the experiment, it was found that X-ray diffraction method can be used for the measurement of the film thickness of a few microns or above by utilizing the eccentricity caused by the film thickness. Especially it has the advantage of being able to measure thick films that X-rays will not penetrate, without being influenced by the chemical structure of the film or the substrates. (author)

Film thickness determining method of the silicon isotope superlattices by SIMS

International Nuclear Information System (INIS)

Takano, Akio; Shimizu, Yasuo; Itoh, Kohei M.

2008-01-01

It is becoming important to evaluate silicon self-diffusion with progress of a silicon semiconductor industry. In order to evaluate the self-diffusion of silicon, silicon isotope superlattices (SLs) is the only marker. For this reason, it is important to correctly evaluate a film thickness and a depth distribution of isotope SLs by secondary ion mass spectrometry (SIMS). As for film thickness, it is difficult to estimate the thicknesses correctly if the cycles of SLs are short. In this work, first, we report the determination of the film thickness for short-period SLs using mixing roughness-information (MRI) analysis to SIMS profile. Next, the uncertainty of the conventional method to determine the film thicknesses of SLs is determined. It was found that the conventional methods cannot correctly determine film thickness of short-period-isotope SLs where film thickness differs for every layer

Effect of thickness on optical properties of thermally evaporated SnS films

International Nuclear Information System (INIS)

Selim, M.S.; Gouda, M.E.; El-Shaarawy, M.G.; Salem, A.M.; Abd El-Ghany, W.A.

2013-01-01

The effect of film thickness on the structure and optical properties of thermally evaporated SnS film has been studied. SnS films with different thicknesses in the range 152–585 nm were deposited onto clean glass substrates at room temperature. X-ray diffraction study revealed that SnS films of thickness ≥ 283 nm are crystalline, whereas films of lower thickness exhibit poor crystalline with more amorphous background. The crystalline nature of the lower film thickness has been confirmed using transmission electron microscope and the corresponding electron diffraction pattern. The thicker film samples showed nearly stoichiometric chemical composition; however, thinner samples are deficient in S and rich in Sn. The optical property of the deposited films has been investigated in the wavelength range 350–2500 nm. The refractive index increases notably with increasing film thickness. The refractive index for the investigated film thicknesses are adequately described by the effective-single-oscillator model. The static refractive index and the static dielectric constant have been calculated. Analysis of the optical absorption coefficient revealed the presence of direct optical transition and the corresponding band gap values were found to decrease as the film thickness increases. - Highlights: ► X-ray diffraction was used to study the structure of SnS films. ► Transmission electron microscope confirms the crystalline state of SnS films. ► The refractive index increases notably with increasing the film thickness. ► The optical band gap of SnS films decreases with increasing film thickness

Investigation of ZnTe thin films grown by Pulsed Laser Deposition method

International Nuclear Information System (INIS)

Kotlyarchuk, B.; Savchuk, V.

2007-01-01

This paper is devoted to optimization of the Pulsed Laser Deposition (PLD) growth condition of ZnTe films on various substrates and subsequent investigation of relevant parameters of growth process, structural, optical and electrical properties of grown films. Studies of the effect of growth parameters on the structural quality and properties of grown films were carried out. X-ray diffraction measurements showed that the ZnTe films, which have been deposited at optimal substrate temperatures, were characterized by a (111) preferred orientation with large average grain size. The optical transmission and reflectance in the energy range 1.5-5.5 eV for films grown at various substrate temperatures were measured. We calculated the variation in the absorption coefficient with the photon energy from the transmittance spectrum for samples grown at various substrate temperatures. Obtained data were analyzed and the value of the absorption coefficient, for allowed direct transitions, has been determined as a function of photon energy. We found that the undoped ZnTe films, which were grown by the PLD method, are typically p-type and possess resistivity in the range of 10 3 Ωcm at room temperature. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Electroplated thick-film cobalt platinum permanent magnets

International Nuclear Information System (INIS)

Oniku, Ololade D.; Qi, Bin; Arnold, David P.

2016-01-01

The material and magnetic properties of multi-micron-thick (up to 6 μm) L1 0 CoPt magnetic films electroplated onto silicon substrates are investigated as candidate materials for integration in silicon-based microsystems. The influence of various process conditions on the structure and magnetic properties of electroplated CoPt thick-films is studied in order to better understand the complex process/structure/property relationships associated with the electroplated films. Process variables studied here include different seed layers, electroplating current densities (ranging from 25–200 mA/cm 2 ), deposition times (up to 60 min), and post-deposition annealing times and temperatures. Analyses include film morphology, film thickness, composition, surface roughness, grain size, phase volume fractions, and L1 0 ordering parameter. Key correlations are found relating process and structure variations to the extrinsic magnetic properties (remanence, coercivity, squareness, and energy product). Strong hard magnetic properties (B r ~0.8 T, H ci ~800 kA/m, squareness close to 0.9, and BH max of 100 kJ/m 3 ) are obtained for films deposited on Si/TiN/Ti/Cu at current densities of 100 mA/cm 2 , pH of 7, and subsequently annealed at 675 °C for 30 min. - Highlights: • CoPt films plated up to 6 μm thick on silicon substrates. • A1 to L1 0 phase transformation by annealing in forming gas. • Various process–structure–property relationships explored. • Key results: B r ~0.8 T, H ci ~800 kA/m, squareness 0.9, and BH max ~100 kJ/m 3 .

Strain-free GaN thick films grown on single crystalline ZnO buffer layer with in situ lift-off technique

International Nuclear Information System (INIS)

Lee, S. W.; Minegishi, T.; Lee, W. H.; Goto, H.; Lee, H. J.; Lee, S. H.; Lee, Hyo-Jong; Ha, J. S.; Goto, T.; Hanada, T.; Cho, M. W.; Yao, T.

2007-01-01

Strain-free freestanding GaN layers were prepared by in situ lift-off process using a ZnO buffer as a sacrificing layer. Thin Zn-polar ZnO layers were deposited on c-plane sapphire substrates, which was followed by the growth of Ga-polar GaN layers both by molecular beam epitaxy (MBE). The MBE-grown GaN layer acted as a protecting layer against decomposition of the ZnO layer and as a seeding layer for GaN growth. The ZnO layer was completely in situ etched off during growth of thick GaN layers at low temperature by hydride vapor phase epitaxy. Hence freestanding GaN layers were obtained for the consecutive growth of high-temperature GaN thick layers. The lattice constants of freestanding GaN agree with those of strain-free GaN bulk. Extensive microphotoluminescence study indicates that strain-free states extend throughout the high-temperature grown GaN layers

High-throughput measurement of polymer film thickness using optical dyes

Science.gov (United States)

Grunlan, Jaime C.; Mehrabi, Ali R.; Ly, Tien

2005-01-01

Optical dyes were added to polymer solutions in an effort to create a technique for high-throughput screening of dry polymer film thickness. Arrays of polystyrene films, cast from a toluene solution, containing methyl red or solvent green were used to demonstrate the feasibility of this technique. Measurements of the peak visible absorbance of each film were converted to thickness using the Beer-Lambert relationship. These absorbance-based thickness calculations agreed within 10% of thickness measured using a micrometer for polystyrene films that were 10-50 µm. At these thicknesses it is believed that the absorbance values are actually more accurate. At least for this solvent-based system, thickness was shown to be accurately measured in a high-throughput manner that could potentially be applied to other equivalent systems. Similar water-based films made with poly(sodium 4-styrenesulfonate) dyed with malachite green oxalate or congo red did not show the same level of agreement with the micrometer measurements. Extensive phase separation between polymer and dye resulted in inflated absorbance values and calculated thickness that was often more than 25% greater than that measured with the micrometer. Only at thicknesses below 15 µm could reasonable accuracy be achieved for the water-based films.

Structural, Optical, and Electrical Characterization of β-Ga2O3 Thin Films Grown by Plasma-Assisted Molecular Beam Epitaxy Suitable for UV Sensing

Directory of Open Access Journals (Sweden)

Abraham Arias

2018-01-01

Full Text Available β-Ga2O3 thin films were grown on c-plane sapphire substrates by plasma-assisted molecular beam epitaxy. The films were grown using an elemental gallium source and oxygen supplied by an RF plasma source. Reflection high-energy electron diffraction (RHEED was used to monitor the surface quality in real time. Both in situ RHEED and ex situ X-ray diffraction confirmed the formation of single crystal β-phase films with excellent crystallinity on c-plane sapphire. Spectroscopic ellipsometry was used to determine the film thicknesses, giving values in the 11.6–18.8 nm range and the refractive index dispersion curves. UV-Vis transmittance measurements revealed that strong absorption of β-Ga2O3 starts at ∼270 nm. Top metal contacts were deposited by thermal evaporation for I-V characterization, which has been carried out in dark, as well as under visible and UV light illumination. The optical and electrical measurements showed that the grown thin films of β-Ga2O3 are excellent candidates for deep-ultraviolet detection and sensing.

Film-thickness dependence of structure formation in ultra-thin polymer blend films

CERN Document Server

Gutmann, J S; Stamm, M

2002-01-01

We investigated the film-thickness dependence of structure formation in ultra-thin polymer blend films prepared from solution. As a model system we used binary blends of statistical poly(styrene-co-p-bromostyrene) copolymers of different degrees of bromination. Ultra-thin-film samples differing in miscibility and film thickness were prepared via spin coating of common toluene solutions onto silicon (100) substrates. The resulting morphologies were investigated with scanning force microscopy, reflectometry and grazing-incidence scattering techniques using both X-rays and neutrons in order to obtain a picture of the sample structure at and below the sample surface. (orig.)

Thickness-dependent spontaneous dewetting morphology of ultrathin Ag films.

Science.gov (United States)

Krishna, H; Sachan, R; Strader, J; Favazza, C; Khenner, M; Kalyanaraman, R

2010-04-16

We show here that the morphological pathway of spontaneous dewetting of ultrathin Ag films on SiO2 under nanosecond laser melting is dependent on film thickness. For films with thickness h of 2 nm < or = h < or = 9.5 nm, the morphology during the intermediate stages of dewetting consisted of bicontinuous structures. For films with 11.5 nm < or = h < or = 20 nm, the intermediate stages consisted of regularly sized holes. Measurement of the characteristic length scales for different stages of dewetting as a function of film thickness showed a systematic increase, which is consistent with the spinodal dewetting instability over the entire thickness range investigated. This change in morphology with thickness is consistent with observations made previously for polymer films (Sharma and Khanna 1998 Phys. Rev. Lett. 81 3463-6; Seemann et al 2001 J. Phys.: Condens. Matter 13 4925-38). Based on the behavior of free energy curvature that incorporates intermolecular forces, we have estimated the morphological transition thickness for the intermolecular forces for Ag on SiO2. The theory predictions agree well with observations for Ag. These results show that it is possible to form a variety of complex Ag nanomorphologies in a consistent manner, which could be useful in optical applications of Ag surfaces, such as in surface enhanced Raman sensing.

High-quality nonpolar a-plane GaN epitaxial films grown on r-plane sapphire substrates by the combination of pulsed laser deposition and metal–organic chemical vapor deposition

Science.gov (United States)

Yang, Weijia; Zhang, Zichen; Wang, Wenliang; Zheng, Yulin; Wang, Haiyan; Li, Guoqiang

2018-05-01

High-quality a-plane GaN epitaxial films have been grown on r-plane sapphire substrates by the combination of pulsed laser deposition (PLD) and metal–organic chemical vapor deposition (MOCVD). PLD is employed to epitaxial growth of a-plane GaN templates on r-plane sapphire substrates, and then MOCVD is used. The nonpolar a-plane GaN epitaxial films with relatively small thickness (2.9 µm) show high quality, with the full-width at half-maximum values of GaN(11\\bar{2}0) along [1\\bar{1}00] direction and GaN(10\\bar{1}1) of 0.11 and 0.30°, and a root-mean-square surface roughness of 1.7 nm. This result is equivalent to the quality of the films grown by MOCVD with a thickness of 10 µm. This work provides a new and effective approach for achieving high-quality nonpolar a-plane GaN epitaxial films on r-plane sapphire substrates.

Nano-Hydroxyapatite Thick Film Gas Sensors

International Nuclear Information System (INIS)

Khairnar, Rajendra S.; Mene, Ravindra U.; Munde, Shivaji G.; Mahabole, Megha P.

2011-01-01

In the present work pure and metal ions (Co and Fe) doped hydroxyapatite (HAp) thick films have been successfully utilized to improve the structural, morphological and gas sensing properties. Nanocrystalline HAp powder is synthesized by wet chemical precipitation route, and ion exchange process is employed for addition of Co and Fe ions in HAp matrix. Moreover, swift heavy ion irradiation (SHI) technique is used to modify the surface of pure and metal ion exchanged HAp with various ion fluence. The structural investigation of pure and metal ion exchanged HAp thick films are carried out using X-ray diffraction and the presence of functional group is observed by means FTIR spectroscopy. Furthermore, surface morphology is visualized by means of SEM and AFM analysis. CO gas sensing study is carried out for, pure and metal ions doped, HAp thick films with detail investigation on operating temperature, response/recovery time and gas uptake capacity. The surface modifications of sensor matrix by SHI enhance the gas response, response/recovery and gas uptake capacity. The significant observation is here to note that, addition of Co and Fe in HAp matrix and surface modification by SHI improves the sensing properties of HAp films drastically resulting in gas sensing at relatively lower temperatures.

Effect of In_xGa_1_−_xAs interlayer on the properties of In_0_._3Ga_0_._7As epitaxial films grown on Si (111) substrates by molecular beam epitaxy

International Nuclear Information System (INIS)

Gao, Fangliang; Wen, Lei; Zhang, Shuguang; Li, Jingling; Zhang, Xiaona; Li, Guoqiang; Liu, Ying

2015-01-01

High-quality In_0_._3Ga_0_._7As films have been epitaxially grown on Si (111) substrate by inserting an In_xGa_1_−_xAs interlayer with various In compositions by molecular beam epitaxy. The effect of In_xGa_1_−_xAs interlayer on the surface morphology and structural properties of In_0_._3Ga_0_._7As films is studied in detail. It reveals that In_0_._3Ga_0_._7As films grown at appropriate In composition in In_xGa_1_−_xAs interlayer exhibit smooth surface with a surface root-mean-square roughness of 1.7 nm; while In_0_._3Ga_0_._7As films grown at different In composition of In_xGa_1_−_xAs interlayer show poorer properties. This work demonstrates a simple but effective method to grow high-quality In_0_._3Ga_0_._7As epilayers on Si substrates, and brings up a broad prospect for the application of InGaAs-based optoelectronic devices on Si substrates. - Highlights: • We provide a simple approach to achieve high-quality In_0_._3Ga_0_._7As films on Si. • An In_0_._2_8Ga_0_._7_2As interlayer can release mismatch strain. • High-quality In_0_._3Ga_0_._7As film is grown on Si using 10-nm-thick interlayer. • Smooth surface In_0_._3Ga_0_._7As film is grown on Si using 10-nm-thick interlayer.

Microstructural and magnetic properties of L10 FePt-C (0 0 1) textured nanocomposite films grown on different intermediate layers

International Nuclear Information System (INIS)

Chen, J S; Chow, G M; Lim, B C; Hu, J F; Ding, Y F; Ju, G

2008-01-01

The FePt : C films with different volume fractions of carbon and different thicknesses were epitaxially grown on a CrRu(2 0 0) underlayer with Pt and MgO intermediate layers. The magnetic properties and microstructure of these FePt : C films were investigated. The FePt : C films grown on the Pt intermediate layer consisted of a continuous layer of FePt, with overlying granular FePt grains, while the FePt : C films grown on the MgO intermediate layer consisted of granular FePt : C layers with overlying granular grains. The formation of the overlying granular FePt grains was attributed to carbon diffusion to the surface which resulted in the second nucleation of FePt. The different interface energies and surface energies of FePt on Pt and MgO intermediate layers caused the formation of an initial continuous FePt layer on the Pt intermediate layer and initial granular FePt layers on the MgO intermediate layer. The coupling between the continuous FePt layer or the granular FePt layer and the overlying granular FePt grains resulted in simultaneous magnetization reversal and thus strong exchange coupling in FePt : C films.

Controlling dielectric and relaxor-ferroelectric properties for energy storage by tuning Pb0.92La0.08Zr0.52Ti0.48O3 film thickness.

Science.gov (United States)

Brown, Emery; Ma, Chunrui; Acharya, Jagaran; Ma, Beihai; Wu, Judy; Li, Jun

2014-12-24

The energy storage properties of Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT) films grown via pulsed laser deposition were evaluated at variable film thickness of 125, 250, 500, and 1000 nm. These films show high dielectric permittivity up to ∼1200. Cyclic I-V measurements were used to evaluate the dielectric properties of these thin films, which not only provide the total electric displacement, but also separate contributions from each of the relevant components including electric conductivity (D1), dielectric capacitance (D2), and relaxor-ferroelectric domain switching polarization (P). The results show that, as the film thickness increases, the material transits from a linear dielectric to nonlinear relaxor-ferroelectric. While the energy storage per volume increases with the film thickness, the energy storage efficiency drops from ∼80% to ∼30%. The PLZT films can be optimized for different energy storage applications by tuning the film thickness to optimize between the linear and nonlinear dielectric properties and energy storage efficiency.

Self-Poling of BiFeO3 Thick Films.

Science.gov (United States)

Khomyakova, Evgeniya; Sadl, Matej; Ursic, Hana; Daniels, John; Malic, Barbara; Bencan, Andreja; Damjanovic, Dragan; Rojac, Tadej

2016-08-03

Bismuth ferrite (BiFeO3) is difficult to pole because of the combination of its high coercive field and high electrical conductivity. This problem is particularly pronounced in thick films. The poling, however, must be performed to achieve a large macroscopic piezoelectric response. This study presents evidence of a prominent and reproducible self-poling effect in few-tens-of-micrometer-thick BiFeO3 films. Direct and converse piezoelectric measurements confirmed that the as-sintered BiFeO3 thick films yield d33 values of up to ∼20 pC/N. It was observed that a significant self-poling effect only appears in cases when the films are heated and cooled through the ferroelectric-paraelectric phase transition (Curie temperature TC ∼ 820 °C). These self-poled films exhibit a microstructure with randomly oriented columnar grains. The presence of a compressive strain gradient across the film thickness cooled from above the TC was experimentally confirmed and is suggested to be responsible for the self-poling effect. Finally, the macroscopic d33 response of the self-poled BiFeO3 film was characterized as a function of the driving-field frequency and amplitude.

Electroplated thick-film cobalt platinum permanent magnets

Energy Technology Data Exchange (ETDEWEB)

Oniku, Ololade D.; Qi, Bin; Arnold, David P., E-mail: darnold@ufl.edu

2016-10-15

The material and magnetic properties of multi-micron-thick (up to 6 μm) L1{sub 0} CoPt magnetic films electroplated onto silicon substrates are investigated as candidate materials for integration in silicon-based microsystems. The influence of various process conditions on the structure and magnetic properties of electroplated CoPt thick-films is studied in order to better understand the complex process/structure/property relationships associated with the electroplated films. Process variables studied here include different seed layers, electroplating current densities (ranging from 25–200 mA/cm{sup 2}), deposition times (up to 60 min), and post-deposition annealing times and temperatures. Analyses include film morphology, film thickness, composition, surface roughness, grain size, phase volume fractions, and L1{sub 0} ordering parameter. Key correlations are found relating process and structure variations to the extrinsic magnetic properties (remanence, coercivity, squareness, and energy product). Strong hard magnetic properties (B{sub r} ~0.8 T, H{sub ci} ~800 kA/m, squareness close to 0.9, and BH{sub max} of 100 kJ/m{sup 3}) are obtained for films deposited on Si/TiN/Ti/Cu at current densities of 100 mA/cm{sup 2}, pH of 7, and subsequently annealed at 675 °C for 30 min. - Highlights: • CoPt films plated up to 6 μm thick on silicon substrates. • A1 to L1{sub 0} phase transformation by annealing in forming gas. • Various process–structure–property relationships explored. • Key results: B{sub r} ~0.8 T, H{sub ci} ~800 kA/m, squareness 0.9, and BH{sub max} ~100 kJ/m{sup 3}.

Microstructural analysis in the depth direction of a heteroepitaxial AlN thick film grown on a trench-patterned template by nanobeam X-ray diffraction

Science.gov (United States)

Shida, K.; Takeuchi, S.; Tohei, T.; Miyake, H.; Hiramatsu, K.; Sumitani, K.; Imai, Y.; Kimura, S.; Sakai, A.

2018-04-01

This work quantitatively assessed the three-dimensional distribution of crystal lattice distortions in an epitaxial AlN thick film grown on a trench-patterned template, using nanobeam X-ray diffraction. Position-dependent ω-2θ-φ mapping clearly demonstrated local tilting, spacing and twisting of lattice planes as well as fluctuations in these phenomena on a sub-micrometer scale comparable to the pitch of the trench-and-terrace patterning. Analysis of the crystal lattice distortion in the depth direction was performed using a newly developed method in which the X-ray nanobeam diffracted from the sample surface to specific depths can be selectively detected by employing a Pt wire profiler. This technique generated depth-resolved ω-2θ-φ maps confirming that fluctuations in lattice plane tilting and spacing greatly depend on the dislocation distribution and the history of the AlN epitaxial growth on the trench-patterned structure. It was also found that both fluctuations were reduced on approaching the AlN surface and, in particular, were sharply reduced at specific depths in the terrace regions. These sharp reductions are attributed to the formation of sacrificial zones with degraded crystal quality around the trenches and possibly lead to raising the crystal quality near the surface of the AlN film.

Quantum confinement effect in Bi anti-dot thin films with tailored pore wall widths and thicknesses

Energy Technology Data Exchange (ETDEWEB)

Park, Y., E-mail: youngok@chem.s.u-tokyo.ac.jp [Department of Chemistry, The University of Tokyo, Bunkyo, Tokyo 113-0033 (Japan); Hirose, Y.; Fukumura, T.; Hasegawa, T. [Department of Chemistry, The University of Tokyo, Bunkyo, Tokyo 113-0033 (Japan); Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan); CREST, JST, Bunkyo, Tokyo 113-0033 (Japan); Nakao, S. [Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan); CREST, JST, Bunkyo, Tokyo 113-0033 (Japan); Xu, J. [School of Engineering, Brown University, Providence, Rhode Island 02912 (United States)

2014-01-13

We investigated quantum confinement effects in Bi anti-dot thin films grown on anodized aluminium oxide templates. The pore wall widths (w{sub Bi}) and thickness (t) of the films were tailored to have values longer or shorter than Fermi wavelength of Bi (λ{sub F} = ∼40 nm). Magnetoresistance measurements revealed a well-defined weak antilocalization effect below 10 K. Coherence lengths (L{sub ϕ}) as functions of temperature were derived from the magnetoresistance vs field curves by assuming the Hikami-Larkin-Nagaoka model. The anti-dot thin film with w{sub Bi} and t smaller than λ{sub F} showed low dimensional electronic behavior at low temperatures where L{sub ϕ}(T) exceed w{sub Bi} or t.

Measurement of the thickness of thin films by backscattered protons

International Nuclear Information System (INIS)

Samaniego, L.E.Q.

1976-07-01

The method of backscattered protons has been used to measure the thickness of thin films. A monoenergetic beam of protons is directed on the film to be measured and the backscattered protons are detected with a particle detector. The film thickness is calculated from the energy spectrum of the protons. In the case of films consisting of several layers of elements with well separated atomic masses, it is possible to separate the spectra of protons scattered from the different elements, permitting a measurement of the thicknesses of the different layers. The method consists of calculating the energy loss of the protons throughout their trajectory, from the point of incidence on the film to the final detection. Thicknesses were measured for the following film combinations: gold on mylar, chromium on mylar, gold on chromium on mylar, and pure mylar. (Author) [pt

Polarity inversion of AlN film grown on nitrided a-plane sapphire substrate with pulsed DC reactive sputtering

Directory of Open Access Journals (Sweden)

Marsetio Noorprajuda

2018-04-01

Full Text Available The effect of oxygen partial pressure (PO2 on polarity and crystalline quality of AlN films grown on nitrided a-plane sapphire substrates by pulsed direct current (DC reactive sputtering was investigated as a fundamental study. The polarity inversion of AlN from nitrogen (−c-polarity to aluminum (+c-polarity occurred during growth at a high PO2 of 9.4×103 Pa owing to Al-O octahedral formation at the interface of nitrided layer and AlN sputtered film which reset the polarity of AlN. The top part of the 1300 nm-thick AlN film sputtered at the high PO2 was polycrystallized. The crystalline quality was improved owing to the high kinetic energy of Al sputtered atom in the sputtering phenomena. Thinner AlN films were also fabricated at the high PO2 to eliminate the polycrystallization. For the 200 nm-thick AlN film sputtered at the high PO2, the full width at half-maximum values of the AlN (0002 and (10−12 X-ray diffraction rocking curves were 47 and 637 arcsec, respectively.

High-throughput characterization of film thickness in thin film materials libraries by digital holographic microscopy

International Nuclear Information System (INIS)

Lai Yiuwai; Hofmann, Martin R; Ludwig, Alfred; Krause, Michael; Savan, Alan; Thienhaus, Sigurd; Koukourakis, Nektarios

2011-01-01

A high-throughput characterization technique based on digital holography for mapping film thickness in thin-film materials libraries was developed. Digital holographic microscopy is used for fully automatic measurements of the thickness of patterned films with nanometer resolution. The method has several significant advantages over conventional stylus profilometry: it is contactless and fast, substrate bending is compensated, and the experimental setup is simple. Patterned films prepared by different combinatorial thin-film approaches were characterized to investigate and demonstrate this method. The results show that this technique is valuable for the quick, reliable and high-throughput determination of the film thickness distribution in combinatorial materials research. Importantly, it can also be applied to thin films that have been structured by shadow masking.

High-throughput characterization of film thickness in thin film materials libraries by digital holographic microscopy.

Science.gov (United States)

Lai, Yiu Wai; Krause, Michael; Savan, Alan; Thienhaus, Sigurd; Koukourakis, Nektarios; Hofmann, Martin R; Ludwig, Alfred

2011-10-01

A high-throughput characterization technique based on digital holography for mapping film thickness in thin-film materials libraries was developed. Digital holographic microscopy is used for fully automatic measurements of the thickness of patterned films with nanometer resolution. The method has several significant advantages over conventional stylus profilometry: it is contactless and fast, substrate bending is compensated, and the experimental setup is simple. Patterned films prepared by different combinatorial thin-film approaches were characterized to investigate and demonstrate this method. The results show that this technique is valuable for the quick, reliable and high-throughput determination of the film thickness distribution in combinatorial materials research. Importantly, it can also be applied to thin films that have been structured by shadow masking.

Effect of BST film thickness on the performance of tunable interdigital capacitors grown by MBE

Science.gov (United States)

Meyers, Cedric J. G.; Freeze, Christopher R.; Stemmer, Susanne; York, Robert A.

2017-12-01

Voltage-tunable, interdigital capacitors (IDCs) were fabricated on Ba0.29Sr0.71TiO3 grown by hybrid molecular beam epitaxy (MBE). In this growth technique, we utilize the metal-organic precursor titanium tetraisopropoxide rather than solid-source Ti as with conventional MBE. Two samples of varying BaxSr(1-x)TiO3 (BST) thicknesses were fabricated and analyzed. High-quality, epitaxial Pt electrodes were deposited by sputtering from a high-purity Pt target at 825 °C. The Pt electrodes were patterned and etched by argon ion milling, passivated with reactively sputtered SiO2, and then metallized with lift-off Ti/Au. The fabricated devices consisted of two-port IDCs embedded in ground-signal-ground, coplanar waveguide (CPW) transmission lines to enable radio-frequency (RF) probing. The sample included open and thru de-embedding structures to remove pad and CPW parasitic impedances. Two-port RF scattering (S) parameters were measured from 100 MHz to 40 GHz while DC bias was stepped from 0 V to 100 V. The IDCs exhibit a high zero-bias radio-frequency (RF) quality factor (Q) approaching 200 at 1 GHz and better than 2.3:1 capacitance tuning for the 300-nm-thick sample. Differences in the Q(V) and C(V) response with varying thicknesses indicate that unknown higher order material phenomena are contributing to the loss and tuning characteristics of the material.

Subtractive fabrication of ferroelectric thin films with precisely controlled thickness

Science.gov (United States)

Ievlev, Anton V.; Chyasnavichyus, Marius; Leonard, Donovan N.; Agar, Joshua C.; Velarde, Gabriel A.; Martin, Lane W.; Kalinin, Sergei V.; Maksymovych, Petro; Ovchinnikova, Olga S.

2018-04-01

The ability to control thin-film growth has led to advances in our understanding of fundamental physics as well as to the emergence of novel technologies. However, common thin-film growth techniques introduce a number of limitations related to the concentration of defects on film interfaces and surfaces that limit the scope of systems that can be produced and studied experimentally. Here, we developed an ion-beam based subtractive fabrication process that enables creation and modification of thin films with pre-defined thicknesses. To accomplish this we transformed a multimodal imaging platform that combines time-of-flight secondary ion mass spectrometry with atomic force microscopy to a unique fabrication tool that allows for precise sputtering of the nanometer-thin layers of material. To demonstrate fabrication of thin-films with in situ feedback and control on film thickness and functionality we systematically studied thickness dependence of ferroelectric switching of lead-zirconate-titanate, within a single epitaxial film. Our results demonstrate that through a subtractive film fabrication process we can control the piezoelectric response as a function of film thickness as well as improve on the overall piezoelectric response versus an untreated film.

Post-annealing effects on pulsed laser deposition-grown GaN thin films

International Nuclear Information System (INIS)

Cheng, Yu-Wen; Wu, Hao-Yu; Lin, Yu-Zhong; Lee, Cheng-Che; Lin, Ching-Fuh

2015-01-01

In this work, the post-annealing effects on gallium nitride (GaN) thin films grown from pulsed laser deposition (PLD) are investigated. The as-deposited GaN thin films grown from PLD are annealed at different temperatures in nitrogen ambient. Significant changes of the GaN crystal properties are observed. Raman spectroscopy is used to observe the crystallinity, the change of residual stress, and the thermal decomposition of the annealed GaN thin films. X-ray diffraction is also applied to identify the crystal phase of GaN thin films, and the surface morphology of GaN thin films annealed at different temperatures is observed by scanning electron microscopy. Through the above analyses, the GaN thin films grown by PLD undergo three stages: phase transition, stress alteration, and thermal decomposition. At a low annealing temperature, the rock salt GaN in GaN films is transformed into wurtzite. The rock salt GaN diminishes with increasing annealing temperature. At a medium annealing temperature, the residual stress of the film changes significantly from compressive strain to tensile strain. As the annealing temperature further increases, the GaN undergoes thermal decomposition and the surface becomes granular. By investigating the annealing temperature effects and controlling the optimized annealing temperature of the GaN thin films, we are able to obtain highly crystalline and strain-free GaN thin films by PLD. - Highlights: • The GaN thin film is grown on sapphire by pulsed laser deposition. • The GaN film undergoes three stages with increasing annealing temperature. • In the first stage, the film transfers from rock salt to wurtzite phase. • In the second stage, the stress in film changes from compressive to tensile. • In the final stage, the film thermally decomposes and becomes granular

Intrinsic flux pinning mechanisms in different thickness MgB2 films

Directory of Open Access Journals (Sweden)

C. Yang

2017-03-01

Full Text Available MgB2 films in four thickness (60 nm, 200nm, 600nm and 1μm have been fabricated by hybrid physical–chemical vapor deposition technique (HPCVD. By measuring the magnetization hysteresis loops and the resistivity, we have obtained the transport and magnetic properties of the four films. After that, the pinning mechanisms in them were discussed. Comparing the pinning behaviors in these ultrathin films, thin films and thick films, it was found that there exist different pinning types in MgB2 films of different thickness. In combination with the study of the surface morphology, cross-section and XRD results, we concluded that MgB2 films had different growth modes in different growth stages. For thin films, films grew along c axis, and grain boundaries acted as surface pinning. While for thick films, films grew along c axis at first, and then changed to a-b axis growth. As a result, the a-b axis grains acted as strong volume pinning.

Thickness-dependent appearance of ferromagnetism in Pd(100) ultrathin films

Science.gov (United States)

Sakuragi, S.; Sakai, T.; Urata, S.; Aihara, S.; Shinto, A.; Kageshima, H.; Sawada, M.; Namatame, H.; Taniguchi, M.; Sato, T.

2014-08-01

We report the appearance of ferromagnetism in thin films of Pd(100), which depends on film thickness in the range of 3-5 nm on SrTiO3(100) substrates. X-ray magnetic circular dichroism measurement shows the intrinsic nature of ferromagnetism in Pd(100) films. The spontaneous magnetization in Pd(100) films, corresponding to is 0.61μB/atom, is comparable to Ni, and it changes in an oscillatory manner depending on film thickness, where the period quantitatively agrees with the theoretical prediction based on the two-dimensional quantum well in the film. This indicates that the discrete electronic states in the quantum well shift to Fermi energy to satisfy the condition for ferromagnetism (Stoner criterion) at a specific film thickness.

Co2FeAl Heusler thin films grown on Si and MgO substrates: Annealing temperature effect

International Nuclear Information System (INIS)

Belmeguenai, M.; Tuzcuoglu, H.; Zighem, F.; Chérif, S. M.; Moch, P.; Gabor, M. S.; Petrisor, T.; Tiusan, C.

2014-01-01

10 nm and 50 nm Co 2 FeAl (CFA) thin films have been deposited on MgO(001) and Si(001) substrates by magnetron sputtering and annealed at different temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth (according to CFA(001)[110]//MgO(001)[100] epitaxial relation) for CFA films grown on a Si and on a MgO substrate, respectively. For these later, the chemical order varies from the A2 phase to the B2 phase when increasing the annealing temperature (T a ), while only the A2 disorder type has been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR) measurements revealed that the in-plane anisotropy results from the superposition of a uniaxial and a fourfold symmetry term for CFA grown on MgO substrates. This fourfold anisotropy, which disappears completely for samples grown on Si, is in accord with the crystal structure of the samples. The fourfold anisotropy field decreases when increasing T a , while the uniaxial anisotropy field is nearly unaffected by T a within the investigated range. The MS-FMR data also allow for concluding that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with T a . Finally, the FMR linewidth decreases when increasing T a , due to the enhancement of the chemical order. We derive a very low intrinsic damping parameter (1.1×10 −3 and 1.3×10 −3 for films of 50 nm thickness annealed at 615 °C grown on MgO and on Si, respectively)

A „Hybrid“ Thin-Film pH Sensor with Integrated Thick-Film Reference

OpenAIRE

Simonis, Anette; Krings, Thomas; Lüth, Hans; Wang, Joseph; Schöning, Michael J.

2001-01-01

A reference electrode fabricated by means of thick-film technique is deposited onto a silicon substrate and combined with a thin-film pH sensor to a “hybrid†chip system. To evaluate the suitability of this combination, first investigations were carried out. The characteristics of the thin-film pH sensor were studied towards the thick-film Ag/AgCl reference electrode. Measurements were performed in the capacitance/voltage (C/V) and constant capacitance (Concap) mode for different pH ...

The thickness of DLC thin film affects the thermal conduction of HPLED lights

Science.gov (United States)

Hsu, Ming Seng; Huang, Jen Wei; Shyu, Feng Lin

2016-09-01

Thermal dissipation had an important influence in the quantum effect and life of light emitting diodes (LED) because it enabled heat transfer away from electric devices to the aluminum plate for heat removal. In the industrial processing, the quality of the thermal dissipation was decided by the gumming technique between the PCB and aluminum plate. In this study, we made the ceramic thin films of diamond like carbon (DLC) by vacuum sputtering between the substrate and high power light emitting diodes (HPLED) light to check the influence of heat transfer by DLC thin films. The ceramic dielectric coatings were characterized by several subsequent analyses, especially the measurement of real work temperature of HPLEDs. The X-Ray photoelectron spectroscopy (XPS) patterns revealed that ceramic phases were successfully grown onto the substrate. At the same time, the real work temperatures showed the thickness of DLC thin film coating effectively affected the thermal conduction of HPLEDs.

Role of high microwave power on growth and microstructure of thick nanocrystalline diamond films: A comparison with large grain polycrystalline diamond films

Science.gov (United States)

Tang, C. J.; Fernandes, A. J. S.; Girão, A. V.; Pereira, S.; Shi, Fa-Nian; Soares, M. R.; Costa, F.; Neves, A. J.; Pinto, J. L.

2014-03-01

In this work, we study the growth habit of nanocrystalline diamond (NCD) films by exploring the very high power regime, up to 4 kW, in a 5 kW microwave plasma chemical vapour deposition (MPCVD) reactor, through addition of a small amount of nitrogen and oxygen (0.24%) into 4% CH4 in H2 plasma. The coupled effect of high microwave power and substrate temperature on NCD growth behaviour is systematically investigated by varying only power, while fixing the remaining operating parameters. When the power increases from 2 kW to 4 kW, resulting also in rise of the Si substrate temperature higher than 150 °C, the diamond films obtained maintain the NCD habit, while the growth rate increases significantly. The highest growth rate of 4.6 μm/h is achieved for the film grown at 4 kW, which represents a growth rate enhancement of about 15 times compared with that obtained when using 2 kW power. Possible factors responsible for such remarkable growth rate enhancement of the NCD films are discussed. The evolution of NCD growth characteristics such as morphology, microstructure and texture is studied by growing thick films and comparing it with that of large grain polycrystalline (PCD) films. One important characteristic of the NCD films obtained, in contrast to PCD films, is that irrespective of deposition time (i.e. film thickness), their grain size and surface roughness remain in the nanometer range throughout the growth. Finally, based on our present and previous experimental results, a potential parameter window is established for fast growth of NCD films under high power conditions.

Thickness dependence of the quantum Hall effect in films of the three-dimensional Dirac semimetal Cd3As2

Directory of Open Access Journals (Sweden)

Manik Goyal

2018-02-01

Full Text Available Low-temperature magnetotransport studies are reported for (112Cd3As2 films grown on (111CdTe by molecular beam epitaxy as a function of the Cd3As2 film thickness. All films show Shubnikov-de Haas oscillations. An even-integer quantum Hall effect is observed for films thinner than 70 nm. For the thinnest films, the bulk is gapped and transport at low temperatures occurs only via the gapless, two-dimensional states. The lowest Landau level is reached at ∼10 T, and the longitudinal resistance nearly vanishes at the plateaus in the Hall resistance. The results are discussed in the context of the current theoretical understanding of topological surface states in three-dimensional Dirac semimetals.

Conformity and structure of titanium oxide films grown by atomic layer deposition on silicon substrates

Energy Technology Data Exchange (ETDEWEB)

Jogi, Indrek [University of Tartu, Institute of Experimental Physics and Technology, Taehe 4, 51010, Tartu (Estonia)], E-mail: indrek.jogi@ut.ee; Paers, Martti; Aarik, Jaan; Aidla, Aleks [University of Tartu, Institute of Physics, Riia 142, 51014, Tartu (Estonia); Laan, Matti [University of Tartu, Institute of Experimental Physics and Technology, Taehe 4, 51010, Tartu (Estonia); Sundqvist, Jonas; Oberbeck, Lars; Heitmann, Johannes [Qimonda Dresden GmbH and Co. OHG, Koenigsbruecker Strasse 180, 01099, Dresden (Germany); Kukli, Kaupo [University of Tartu, Institute of Experimental Physics and Technology, Taehe 4, 51010, Tartu (Estonia)

2008-06-02

Conformity and phase structure of atomic layer deposited TiO{sub 2} thin films grown on silicon substrates were studied. The films were grown using TiCl{sub 4} and Ti(OC{sub 2}H{sub 5}){sub 4} as titanium precursors in the temperature range from 125 to 500 {sup o}C. In all cases perfect conformal growth was achieved on patterned substrates with elliptical holes of 7.5 {mu}m depth and aspect ratio of about 1:40. Conformal growth was achieved with process parameters similar to those optimized for the growth on planar wafers. The dominant crystalline phase in the as-grown films was anatase, with some contribution from rutile at relatively higher temperatures. Annealing in the oxygen ambient resulted in (re)crystallization whereas the effect of annealing depended markedly on the precursors used in the deposition process. Compared to films grown from TiCl{sub 4}, the films grown from Ti(OC{sub 2}H{sub 5}){sub 4} were transformed into rutile in somewhat greater extent, whereas in terms of step coverage the films grown from Ti(OC{sub 2}H{sub 5}){sub 4} remained somewhat inferior compared to the films grown from TiCl{sub 4}.

Order in nanometer thick intergranular films at Au-sapphire interfaces

Energy Technology Data Exchange (ETDEWEB)

Baram, Mor [Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Garofalini, Stephen H. [Department of Materials Science and Engineering, Rutgers University, Piscataway, NJ 08854-8065 (United States); Kaplan, Wayne D., E-mail: kaplan@tx.technion.ac.il [Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

2011-08-15

Highlights: {yields} Au particles were equilibrated on (0 0 0 1) sapphire in the presence of anorthite. {yields} 1.2 nm thick equilibrium films (complexions) were formed at the Au-sapphire interfaces. {yields} Quantitative HRTEM was used to study the atomistic structure of the films. {yields} Structural order was observed in the 1.2 nm thick films adjacent to the sapphire crystal. {yields} This demonstrates that ordering is an intrinsic part of equilibrium intergranular films. - Abstract: In recent years extensive studies on interfaces have shown that {approx}1 nm thick intergranular films (IGF) exist at interfaces in different material systems, and that IGF can significantly affect the materials' properties. However, there is great deal of uncertainty whether such films are amorphous or partially ordered. In this study specimens were prepared from Au particles that were equilibrated on sapphire substrates in the presence of anorthite glass, leading to the formation of 1.2 nm thick IGF at the Au-sapphire interfaces. Site-specific cross-section samples were characterized using quantitative high resolution transmission electron microscopy to study the atomistic structure of the films. Order was observed in the 1.2 nm thick films adjacent to the sapphire crystal in the form of 'Ca cages', experimentally demonstrating that ordering is an intrinsic part of IGF, as predicted from molecular dynamics and diffuse interface theory.

Thickness dependent ferromagnetism in thermally decomposed NiO thin films

Energy Technology Data Exchange (ETDEWEB)

Ravikumar, Patta; Kisan, Bhagaban; Perumal, Alagarsamy, E-mail: perumal@iitg.ernet.in

2016-11-15

We report the effects of film thickness, annealing temperature and annealing environments on thermal decomposition behavior and resulting magnetic properties of NiO (t=50–300 nm) thin films. All the NiO films were prepared directly on thermally oxidized Si at ambient temperature using magnetron sputtering technique and post annealed at different temperatures (T{sub A}) under vacuum and oxygen atmospheres. As-deposited films exhibit face centered cubic structure with large lattice constant due to strain induced during sputtering process. With increasing T{sub A}, the lattice constant decreases due to the release of strain and thickness dependent thermal decomposition reaction of NiO into Ni has been observed for the NiO films annealed at 500 °C under vacuum condition. As a result, the antiferromagnetic nature of the as-deposited NiO films transforms into ferromagnetic one with dominant thickness dependent ferromagnetic behavior at room temperature. In addition, the existence of both Ni and NiO phases in the annealed NiO films shows noticeable exchange bias under field cooling condition. The behavior of thermal decomposition was not observed for the NiO films annealed under oxygen condition which results in no detectable change in the magnetic properties. The observed results are discussed on the basis of thickness dependent thermal decomposition in NiO films with increasing T{sub A} and changing annealing conditions. - Highlights: • Preparation of highly strained single layer NiO films with different thicknesses. • Study the effects of annealing under different environments on crystal structure. • Understanding the origin of thickness dependent thermal decomposition reaction. • Investigate the role of thermal decomposition reaction on the magnetic properties. • Study the interaction between NiO and Ni phases on the exchange bias mechanism.

A method to measure the mean thickness and non-uniformity of non-uniform thin film by alpha-ray thickness gauge

International Nuclear Information System (INIS)

Miyahara, Hiroshi; Yoshida, Makoto; Watanabe, Tamaki

1977-01-01

The α-ray thickness gauge is used to measure non-destructively the thicknesses of thin films, and up to the present day, a thin film with uniform thickness is only taken up as the object of α-ray thickness gauge. When the thickness is determined from the displacement between the absorption curves in the presence and absence of thin film, the absorption curve must be displaced in parallel. When many uniform particles were dispersed as sample, the shape of the absorption curve was calculated as the sum of many absorption curves corresponding to the thin films with different thicknesses. By the comparison of the calculated and measured absorption curves, the number of particles, or the mean superficial density can be determined. This means the extension of thickness measurement from uniform to non-uniform films. Furthermore, these particle models being applied to non-uniform thin film, the possibility of measuring the mean thickness and non-uniformity was discussed. As the result, if the maximum difference of the thickness was more than 0.2 mg/cm 2 , the nonuniformity was considered to distinguish by the usual equipment. In this paper, an α-ray thickness gauge using the absorption curve method was treated, but one can apply this easily to an α-ray thickness gauge using α-ray energy spectra before and after the penetration of thin film. (auth.)

Ultrafast demagnetisation dependence on film thickness: A TDDFT calculation

Science.gov (United States)

Singh, N.; Sharma, S.

2018-04-01

Ferromagnetic materials when subjected to intense laser pulses leads to reduction of their magnetisation on an ultrafast scale. Here, we perform an ab-initio calculation to study the behavior of ultrafast demagnetisation as a function of film thickness for Nickel as compared to the bulk of the material. In thin films surface formation results in amplification of demagnetisation with the percentage of demagnetisation depending upon the film thickness.

Quality of YBCO thin films grown on LAO substrates exposed to the film deposition - film removal processes

Energy Technology Data Exchange (ETDEWEB)

Blagoev, B; Nurgaliev, T [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria); Mozhaev, P B [Institute of Physics and Technology, Russian Academy of Sciences, 117218 Moscow (Russian Federation); Sardela, M; Donchev, T [Materials Research Laboratory, University of Illinois, 104 South Goodwin Ave., Urbana, IL 61801 (United States)], E-mail: blago_sb@yahoo.com

2008-05-01

The characteristics are investigated of high temperature superconducting YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) films grown on LaAlO{sub 3} (LAO) substrates being exposed a different number of times to YBCO film deposition and acid-solution-based cleaning procedures. Possible mechanisms of degradation of the substrate surface quality reflecting on the growing YBCO film parameters are discussed and analyzed.

Percolation effect in thick film superconductors

Energy Technology Data Exchange (ETDEWEB)

Sali, R.; Harsanyi, G. [Technical Univ. of Budapest (Hungary)

1994-12-31

A thick film superconductor paste has been developed to study the properties of granulated superconductor materials, to observe the percolation effect and to confirm the theory of the conducting mechanism in the superconducting thick films. This paste was also applied to make a superconducting planar transformer. Due to high T{sub c} and advantageous current density properties the base of the paste was chosen to be of Bi(Pb)SrCaCuO system. For contacts a conventional Ag/Pt paste was used. The critical temperature of the samples were between 110 K and 115 K depending on the printed layer thickness. The critical current density at the boiling temperature of the liquid He- was between 200-300 A/cm{sup 2}. The R(T) and V(I) functions were measured with different parameters. The results of the measurements have confirmed the theory of conducting mechanism in the material. The percolation structure model has been built and described. As an application, a superconducting planar thick film transformer was planned and produced. Ten windings of the transformer were printed on one side of the alumina substrate and one winding was printed on the other side. The coupling between the two sides was possible through the substrate. The samples did not need special drying and firing parameters. After the preparation, the properties of the transformer were measured. The efficiency and the losses were determined. Finally, some fundamental advantages and problems of the process were discussed.

Percolation effect in thick film superconductors

International Nuclear Information System (INIS)

Sali, R.; Harsanyi, G.

1994-01-01

A thick film superconductor paste has been developed to study the properties of granulated superconductor materials, to observe the percolation effect and to confirm the theory of the conducting mechanism in the superconducting thick films. This paste was also applied to make a superconducting planar transformer. Due to high T c and advantageous current density properties the base of the paste was chosen to be of Bi(Pb)SrCaCuO system. For contacts a conventional Ag/Pt paste was used. The critical temperature of the samples were between 110 K and 115 K depending on the printed layer thickness. The critical current density at the boiling temperature of the liquid He- was between 200-300 A/cm 2 . The R(T) and V(I) functions were measured with different parameters. The results of the measurements have confirmed the theory of conducting mechanism in the material. The percolation structure model has been built and described. As an application, a superconducting planar thick film transformer was planned and produced. Ten windings of the transformer were printed on one side of the alumina substrate and one winding was printed on the other side. The coupling between the two sides was possible through the substrate. The samples did not need special drying and firing parameters. After the preparation, the properties of the transformer were measured. The efficiency and the losses were determined. Finally, some fundamental advantages and problems of the process were discussed

Co{sub 2}FeAl Heusler thin films grown on Si and MgO substrates: Annealing temperature effect

Energy Technology Data Exchange (ETDEWEB)

Belmeguenai, M., E-mail: belmeguenai.mohamed@univ-paris13.fr; Tuzcuoglu, H.; Zighem, F.; Chérif, S. M.; Moch, P. [LSPM (CNRS-UPR 3407), 99 avenue Jean-Baptiste Clément, Université Paris 13, 93430 Villetaneuse (France); Gabor, M. S., E-mail: mihai.gabor@phys.utcluj.ro; Petrisor, T. [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Str. Memorandumului No. 28 RO-400114 Cluj-Napoca (Romania); Tiusan, C. [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Str. Memorandumului No. 28 RO-400114 Cluj-Napoca (Romania); Institut Jean Lamour, CNRS, Université de Nancy, BP 70239, F–54506 Vandoeuvre (France)

2014-01-28

10 nm and 50 nm Co{sub 2}FeAl (CFA) thin films have been deposited on MgO(001) and Si(001) substrates by magnetron sputtering and annealed at different temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth (according to CFA(001)[110]//MgO(001)[100] epitaxial relation) for CFA films grown on a Si and on a MgO substrate, respectively. For these later, the chemical order varies from the A2 phase to the B2 phase when increasing the annealing temperature (T{sub a}), while only the A2 disorder type has been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR) measurements revealed that the in-plane anisotropy results from the superposition of a uniaxial and a fourfold symmetry term for CFA grown on MgO substrates. This fourfold anisotropy, which disappears completely for samples grown on Si, is in accord with the crystal structure of the samples. The fourfold anisotropy field decreases when increasing T{sub a}, while the uniaxial anisotropy field is nearly unaffected by T{sub a} within the investigated range. The MS-FMR data also allow for concluding that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with T{sub a}. Finally, the FMR linewidth decreases when increasing T{sub a}, due to the enhancement of the chemical order. We derive a very low intrinsic damping parameter (1.1×10{sup −3} and 1.3×10{sup −3} for films of 50 nm thickness annealed at 615 °C grown on MgO and on Si, respectively)

Thickness and angular dependent magnetic anisotropy of La0.67Sr0.33MnO3 thin films by Vectorial Magneto Optical Kerr Magnetometry

Science.gov (United States)

Chaluvadi, S. K.; Perna, P.; Ajejas, F.; Camarero, J.; Pautrat, A.; Flament, S.; Méchin, L.

2017-10-01

We investigate the in-plane magnetic anisotropy in La0.67Sr0.33MnO3 thin films grown on SrTiO3 (001) substrate using angular dependent room temperature Vectorial Magneto-Optical Kerr Magnetometry. The experimental data reveals that the magnetic anisotropy symmetry landscape significantly changes depending upon the strain and thickness. At low film thickness (12 and 25 nm) the dominant uniaxial anisotropy is due to interface effects, step edges due to mis-cut angle of SrTiO3 substrate. At intermediate thickness, the magnetic anisotropy presents a competition between magnetocrystalline (biaxial) and substrate step induced (uniaxial) anisotropy. Depending upon their relative strengths, a profound biaxial or uniaxial or mixed anisotropy is favoured. Above the critical thickness, magnetocrystalline anisotropy dominates all other effects and shows a biaxial anisotropy.

Thickness dependence of J_c (0) in MgB_2 films

International Nuclear Information System (INIS)

Chen, Yiling; Yang, Can; Jia, Chunyan; Feng, Qingrong; Gan, Zizhao

2016-01-01

Highlights: • A serial of MgB_2 superconducting films from 10 nm to 8 µm have been prepared. • T_c and J_c (5 K, 0 T) of films are high. • J_c (5 K, 0 T) reaches its maximum 2.3 × 10"8 A cm"−"2 for 100 nm films. • The relationship between thickness and J_c has been discussed in detail. - Abstract: MgB_2 superconducting films, whose thicknesses range from 10 nm to 8 µm, have been fabricated on SiC substrates by hybrid physical–chemical vapor deposition (HPCVD) method. It is the first time that the T_c and the J_c of MgB_2 films are studied on such a large scale. It is found that with the increasing of thickness, T_c elevates first and then keeps roughly stable except for some slight fluctuations, while J_c (5 K, 0 T) experiences a sharp increase followed by a relatively slow fall. The maximum J_c (5 K, 0 T) = 2.3 × 10"8 A cm"−"2 is obtained for 100 nm films, which is the experimental evidence for preparing high-quality MgB_2 films by HPCVD method. Thus, this work may provide guidance on choosing the suitable thickness for applications. Meanwhile, the films prepared by us cover ultrathin films, thin films and thick films, so the study on them will bring a comprehensive understanding of MgB_2 films.

Critical thickness for strain relaxation of Ge{sub 1−x}Sn{sub x} (x ≤ 0.17) grown by molecular beam epitaxy on Ge(001)

Energy Technology Data Exchange (ETDEWEB)

Wang, Wei; Zhou, Qian; Dong, Yuan; Yeo, Yee-Chia, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Tok, Eng Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

2015-06-08

We investigated the critical thickness (h{sub c}) for plastic relaxation of Ge{sub 1−x}Sn{sub x} grown by molecular beam epitaxy. Ge{sub 1−x}Sn{sub x} films with various Sn mole fraction x (x ≤ 0.17) and different thicknesses were grown on Ge(001). The strain relaxation of Ge{sub 1−x}Sn{sub x} films and the h{sub c} were investigated by high-resolution x-ray diffraction and reciprocal space mapping. It demonstrates that the measured h{sub c} values of Ge{sub 1−x}Sn{sub x} layers are as much as an order of magnitude larger than that predicted by the Matthews and Blakeslee (M-B) model. The People and Bean (P-B) model was also used to predict the h{sub c} values in Ge{sub 1−x}Sn{sub x}/Ge system. The measured h{sub c} values for various Sn content follow the trend, but slightly larger than that predicted by the P-B model.

Low temperature CVD growth of ultrathin carbon films

Directory of Open Access Journals (Sweden)

Chao Yang

2016-05-01

Full Text Available We demonstrate the low temperature, large area growth of ultrathin carbon films by chemical vapor deposition under atmospheric pressure on various substrates. In particularly, uniform and continuous carbon films with the thickness of 2-5 nm were successfully grown at a temperature as low as 500 oC on copper foils, as well as glass substrates coated with a 100 nm thick copper layer. The characterizations revealed that the low-temperature-grown carbon films consist on few short, curved graphene layers and thin amorphous carbon films. Particularly, the low-temperature grown samples exhibited over 90% transmittance at a wavelength range of 400-750 nm and comparable sheet resistance in contrast with the 1000oC-grown one. This low-temperature growth method may offer a facile way to directly prepare visible ultrathin carbon films on various substrate surfaces that are compatible with temperatures (500-600oC used in several device processing technologies.

A Study on the Thickness Measurement of Thin Film by Ultrasonic Wave

International Nuclear Information System (INIS)

Han, Eung Kyo; Lee, Jae Joon; Kim, Jae Yeol

1988-01-01

Recently, it is gradually raised necessity that thickness of thin film is measured accurately and managed in industrial circles and medical world. In this study, regarding to the thickness of film which is in opaque object and is beyond distance resolution capacity, thickness measurement was done by MEM-cepstrum analysis of received ultrasonic wave. In measurement results, film thickness which is beyond distance resolution capacity was measured accurately. And within thickness range that don't exist interference, thickness measurement by MEM-ceptrum analysis was impossible

Anomalous size effect in conductivity of Bi films of small thickness

International Nuclear Information System (INIS)

Anopchenko, A.S.; Kashirin, V.Yu.; Komnik, Yu.F.

1995-01-01

Experimental data are obtained at helium temperature, which describe the kinetic properties (conductivity, magnetoresistance and Hall coefficient) of Bi films whose thicknesses are within 100-500 A. The small-thickness Bi films display an anomalous size effect- the growing conductivity at decreasing thickness, and pronounced quantum interference effects - weak electron localization and enhancing electron-electron interaction in a disordered system. The information derived on the kinetic properties of the films is used to identify the character of the changes in the electron and hole concentrations and mobilities with a decreasing thickness. The isotropy of the properties in the films plane due to the axial texture has permitted us to use the equations for a conductor with two types of charge carriers. The used kinetic characteristics correctly take into account the contribution of the quantum corrections related to quantum interference. It is found that the concentration of the charge carries increases appreciably (by about two orders of magnitude) as the film thickness decreases to 100 A, which determines the anomalous size effect in the conductivity of the films

Hexaferrite multiferroics: from bulk to thick films

Science.gov (United States)

Koutzarova, T.; Ghelev, Ch; Peneva, P.; Georgieva, B.; Kolev, S.; Vertruyen, B.; Closset, R.

2018-03-01

We report studies of the structural and microstructural properties of Sr3Co2Fe24O41 in bulk form and as thick films. The precursor powders for the bulk form were prepared following the sol-gel auto-combustion method. The prepared pellets were synthesized at 1200 °C to produce Sr3Co2Fe24O41. The XRD spectra of the bulks showed the characteristic peaks corresponding to the Z-type hexaferrite structure as a main phase and second phases of CoFe2O4 and Sr3Fe2O7-x. The microstructure analysis of the cross-section of the bulk pellets revealed a hexagonal sheet structure. Large areas were observed of packages of hexagonal sheets where the separate hexagonal particles were ordered along the c axis. Sr3Co2Fe24O41 thick films were deposited from a suspension containing the Sr3Co2Fe24O41 powder. The microstructural analysis of the thick films showed that the particles had the perfect hexagonal shape typical for hexaferrites.

Growth mechanisms and thickness effect on the properties of Al-doped ZnO thin films grown on polymeric substrates

Energy Technology Data Exchange (ETDEWEB)

Koidis, Christos; Logothetidis, Stergios; Kassavetis, Spiridon; Laskarakis, Argiris [Lab for Thin Films-Nanosystems and Nanometrology (LTFN), Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Hastas, Nikolaos A.; Valassiades, Odisseas [Solid State Section, Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

2010-07-15

The properties of Al-doped ZnO (AZO) thin films deposited by pulsed DC magnetron sputtering under various target power on polyethylene terephthalate (PET) substrates have been investigated. In situ and real-time spectroscopic ellipsometry (1.5-6.5 eV) has been employed to study the optical properties of the AZO films as well as the growth mechanisms taking place. With X-ray diffraction technique under grazing-incidence geometry, the structural characteristics profiles of the AZO films have been depicted. Nanoindentation measurements revealed information about the mechanical properties of the films and have been correlated to the conductivity measurements towards growth insights understanding. As results have shown, the increase of target power led to the increase of the carrier density as well as the hardness of the AZO films possibly both ascribed to dislocations induced. The stress during the deposition of AZO film under high target power favoured the island growth which is possibly both connected to the formation of defects as electron traps and dislocations as electron sources. Finally, the increase of AZO film thickness led to the increase of the resistivity possibly due to the enrichment of grain boundaries with defects as electron traps. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

The roles of buffer layer thickness on the properties of the ZnO epitaxial films

Energy Technology Data Exchange (ETDEWEB)

Tang, Kun, E-mail: ktang@nju.edu.cn [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Huang, Shimin [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Gu, Shulin, E-mail: slgu@nju.edu.cn [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Zhu, Shunming [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Ye, Jiandong [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Nanjing University Institute of Optoelectronics at Yangzhou, Yangzhou 225009 (China); Xu, Zhonghua; Zheng, Youdou [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China)

2016-12-01

Highlights: • The growth mechanism has been revealed for the ZnO buffers with different thickness. • The surface morphology has been determined as the key factor to affect the epitaxial growth. • The relation between the hexagonal pits from buffers and epi-films has been established. • The hexagonal pits formed in the epi-films have been attributed to the V-shaped defects inheriting from the dislocations in the buffers. • The structural and electrical properties of the V-defects have been presented and analyzed. - Abstract: In this article, the authors have investigated the optimization of the buffer thickness for obtaining high-quality ZnO epi-films on sapphire substrates. The growth mechanism of the buffers with different thickness has been clearly revealed, including the initial nucleation and vertical growth, the subsequent lateral growth with small grain coalescence, and the final vertical growth along the existing larger grains. Overall, the quality of the buffer improves with increasing thickness except the deformed surface morphology. However, by a full-scale evaluation of the properties for the epi-layers, the quality of the epi-film is briefly determined by the surface morphology of the buffer, rather than the structural, optical, or electrical properties of it. The best quality epi-layer has been grown on the buffer with a smooth surface and well-coalescent grains. Meanwhile, due to the huge lattice mismatch between sapphire and ZnO, dislocations are inevitably formed during the growth of buffers. More importantly, as the film grows thicker, the dislocations may attracting other smaller dislocations and defects to reduce the total line energy and thus result in the formation of V-shape defects, which are connected with the bottom of the threading dislocations in the buffers. The V-defects appear as deep and large hexagonal pits from top view and they may act as electron traps which would affect the free carrier concentration of the epi-layers.

The roles of buffer layer thickness on the properties of the ZnO epitaxial films

International Nuclear Information System (INIS)

Tang, Kun; Huang, Shimin; Gu, Shulin; Zhu, Shunming; Ye, Jiandong; Xu, Zhonghua; Zheng, Youdou

2016-01-01

Highlights: • The growth mechanism has been revealed for the ZnO buffers with different thickness. • The surface morphology has been determined as the key factor to affect the epitaxial growth. • The relation between the hexagonal pits from buffers and epi-films has been established. • The hexagonal pits formed in the epi-films have been attributed to the V-shaped defects inheriting from the dislocations in the buffers. • The structural and electrical properties of the V-defects have been presented and analyzed. - Abstract: In this article, the authors have investigated the optimization of the buffer thickness for obtaining high-quality ZnO epi-films on sapphire substrates. The growth mechanism of the buffers with different thickness has been clearly revealed, including the initial nucleation and vertical growth, the subsequent lateral growth with small grain coalescence, and the final vertical growth along the existing larger grains. Overall, the quality of the buffer improves with increasing thickness except the deformed surface morphology. However, by a full-scale evaluation of the properties for the epi-layers, the quality of the epi-film is briefly determined by the surface morphology of the buffer, rather than the structural, optical, or electrical properties of it. The best quality epi-layer has been grown on the buffer with a smooth surface and well-coalescent grains. Meanwhile, due to the huge lattice mismatch between sapphire and ZnO, dislocations are inevitably formed during the growth of buffers. More importantly, as the film grows thicker, the dislocations may attracting other smaller dislocations and defects to reduce the total line energy and thus result in the formation of V-shape defects, which are connected with the bottom of the threading dislocations in the buffers. The V-defects appear as deep and large hexagonal pits from top view and they may act as electron traps which would affect the free carrier concentration of the epi-layers.

Dependences of microstructure and critical current density on the thickness of YBa2Cu3O7-x film prepared by pulsed laser deposition on buffered Ni–W tape

International Nuclear Information System (INIS)

Xu, Da; Wang, Ying; Liu, Linfei; Li, Yijie

2013-01-01

YBa 2 Cu 3 O 7−x (YBCO) films with different thicknesses were fabricated on buffered Ni–W tapes by pulsed laser deposition. The thickness dependences of microstructure and critical current density (J c ) of YBCO film were systematically investigated. The microstructure and surface morphology of YBCO film were characterized by X-ray diffraction, optical microscopy, field emission scanning electron microscopy and atomic force microscopy. And the critical current (I c ) of YBCO film was measured by the conventional four-probe method. We found that the full width at half maximum values of both omega and phi scan rocking curves, the content of a-axis oriented grain, and surface roughness of YBCO film all increased with augmenting the thickness of YBCO film. It was also found that with increasing the thickness of YBCO film from 0.3 μm to 1.5 μm, the I c of YBCO film increased from 72 A/cm to 248 A/cm and yet J c of YBCO film decreased from 2.1 × 10 6 A/cm 2 to 1.6 × 10 6 A/cm 2 . Our results indicated that the microstructure and J c of YBCO film were largely dependent on the thickness of YBCO film under the optimized deposition condition of substrate temperature. - Highlights: ► YBa 2 Cu 3 O 7−x (YBCO) films with different thicknesses were grown on metallic tapes. ► The texture and critical current were dependent on the thickness of YBCO film. ► Thickness effect was weakened by fabricating YBCO film layer by layer

X-ray diffraction measurement of residual stress in sol-gel grown lead zirconate titanate thick films on nickel-based super alloy substrate

Energy Technology Data Exchange (ETDEWEB)

Hoshyarmanesh, Hamidreza; Nehzat, Naser; Salehi, Mehdi [Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Ghodsi, Mojtaba [Sultan Qaboos University, Muscat (Oman)

2015-02-15

Residual compressive stress of Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} thick films was investigated using residual strains derived from X-ray diffraction patterns. Sin{sup 2}ψ method was applied for the 5, 10 and 15 μm sol-gel derived thick films annealed at 700 .deg. C for 1 hr as high frequency structural health monitoring square-shape transducers of 10 x10 mm, deposited onto the curved nickel-based super alloy substrates. A triaxial model was proposed based on piezoelectric constitutive equations, and Bragg's law at a large diffraction angle (∼89°) was utilized considering the electromechanical coupling factor as well as elastic, dielectric and piezoelectric constants. Thickness variations led to a significant change in residual stress magnitudes delineated from more-accurate triaxial model compared to small angle plane-stress results not considering the piezoelectric coupling effects.

The effect of bubble acceleration on the liquid film thickness in micro tubes

Energy Technology Data Exchange (ETDEWEB)

Han, Youngbae, E-mail: bhan@feslab.t.u-tokyo.ac.j [Department of Mechanical Engineering, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656 (Japan); Shikazono, Naoki, E-mail: shika@feslab.t.u-tokyo.ac.j [Department of Mechanical Engineering, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656 (Japan)

2010-08-15

Liquid film thickness is an important parameter for predicting boiling heat transfer in micro tubes. In the previous study (), liquid film thickness under the steady condition was investigated and an empirical correlation for the initial liquid film thickness based on capillary number, Reynolds number and Weber number was proposed. However, under flow boiling conditions, bubble velocity is not constant but accelerated due to evaporation. It is necessary to consider this bubble acceleration effect on the liquid film thickness, since it affects viscous, surface tension and inertia forces in the momentum equation. In addition, viscous boundary layer develops, and it may also affect the liquid film thickness. In the present study, the effect of bubble acceleration is investigated. Laser focus displacement meter is used to measure the liquid film thickness. Ethanol, water and FC-40 are used as working fluids. Circular tubes with three different inner diameters, D = 0.5, 0.7 and 1.0 mm, are used. The increase of liquid film thickness with capillary number is restricted by the bubble acceleration. Finally, an empirical correlation is proposed for the liquid film thickness of accelerated flows in terms of capillary number and Bond number based on the bubble acceleration.

The effect of bubble acceleration on the liquid film thickness in micro tubes

International Nuclear Information System (INIS)

Han, Youngbae; Shikazono, Naoki

2010-01-01

Liquid film thickness is an important parameter for predicting boiling heat transfer in micro tubes. In the previous study (), liquid film thickness under the steady condition was investigated and an empirical correlation for the initial liquid film thickness based on capillary number, Reynolds number and Weber number was proposed. However, under flow boiling conditions, bubble velocity is not constant but accelerated due to evaporation. It is necessary to consider this bubble acceleration effect on the liquid film thickness, since it affects viscous, surface tension and inertia forces in the momentum equation. In addition, viscous boundary layer develops, and it may also affect the liquid film thickness. In the present study, the effect of bubble acceleration is investigated. Laser focus displacement meter is used to measure the liquid film thickness. Ethanol, water and FC-40 are used as working fluids. Circular tubes with three different inner diameters, D = 0.5, 0.7 and 1.0 mm, are used. The increase of liquid film thickness with capillary number is restricted by the bubble acceleration. Finally, an empirical correlation is proposed for the liquid film thickness of accelerated flows in terms of capillary number and Bond number based on the bubble acceleration.

Film thickness dependence of phase separation and dewetting behaviors in PMMA/SAN blend films.

Science.gov (United States)

You, Jichun; Liao, Yonggui; Men, Yongfeng; Shi, Tongfei; An, Lijia

2010-09-21

Film thickness dependence of complex behaviors coupled by phase separation and dewetting in blend [poly(methyl methacrylate) (PMMA) and poly(styrene-ran-acrylonitrile) (SAN)] films on silicon oxide substrate at 175 °C was investigated by grazing incidence ultrasmall-angle X-ray scattering (GIUSAX) and in situ atomic force microscopy (AFM). It was found that the dewetting pathway was under the control of the parameter U(q0)/E, which described the initial amplitude of the surface undulation and original thickness of film, respectively. Furthermore, our results showed that interplay between phase separation and dewetting depended crucially on film thickness. Three mechanisms including dewetting-phase separation/wetting, dewetting/wetting-phase separation, and phase separation/wetting-pseudodewetting were discussed in detail. In conclusion, it is relative rates of phase separation and dewetting that dominate the interplay between them.

Temperature-dependent Hall effect studies of ZnO thin films grown by metalorganic chemical vapour deposition

International Nuclear Information System (INIS)

Roro, K T; Dangbegnon, J K; Sivaraya, S; Westraadt, J E; Neethling, J H; Leitch, A W R; Botha, J R; Kassier, G H

2008-01-01

The electrical properties of zinc oxide (ZnO) thin films of various thicknesses (0.3–4.4 µm) grown by metalorganic chemical vapour deposition on glass substrates have been studied by using temperature-dependent Hall-effect (TDH) measurements in the 18–300 K range. The high quality of the layers has been confirmed with x-ray diffraction, transmission electron microscopy, scanning electron microscopy and photoluminescence techniques. TDH measurements indicate the presence of a degenerate layer which significantly influences the low-temperature data. It is found that the measured mobility generally increases with increasing layer thickness, reaching a value of 120 cm 2 V −1 s −1 at room temperature for the 4.4 µm thick sample. The lateral grain size of the layers is also found to increase with thickness indicating a clear correlation between the size of the surface grains and the electrical properties of corresponding films. Theoretical fits to the Hall data suggest that the bulk conduction of the layers is dominated by a weakly compensated donor with activation energy in the 33–41 meV range and concentration of the order of 10 17 cm −3 , as well as a total acceptor concentration of mid-10 15 cm −3 . Grain boundary scattering is found to be an important limiting factor of the mobility throughout the temperature range considered

Structure and magnetoresistance of La0.67Ca0.33MnO3 films grown coherently on (001)NdGaO3

International Nuclear Information System (INIS)

Bojkov, Yu.A.; Danilov, V.A.; Bojkov, A.Yu.

2003-01-01

The (001) La 0.67 Ca 0.33 MnO 3 films, 40-120 nm thick, grown through the method of the laser evaporation on the (001)NdGaO 3 , are studied. The crystalline lattice parameters, measured for the La 0.67 Ca 0.33 MnO 3 film in the substrate plane α parallel = 3.851 A and along the normal to its surface α perpendicular = 3.850 A practically coincide with the parameter of the pseudocubic elementary cell of the neodymium gallate. The elementary cell volume in the La 0.67 Ca 0.33 MnO 3 film was insignificantly lesser than the corresponding value for the stoichiometric voluminous samples. The position of the maximum on the specific resistance dependence on the temperature did not depend on the La 0.67 Ca 0.33 MnO 3 film thickness. The maximum values of the negative magnetoresistance (MR ≅ 0.25, H = 0.4 T) for the La 0.67 Ca 0.33 MnO 3 films were observed at the temperatures of 239-244 K [ru

Relaxation in Thin Polymer Films Mapped across the Film Thickness by Astigmatic Single-Molecule Imaging

KAUST Repository

Oba, Tatsuya

2012-06-19

We have studied relaxation processes in thin supported films of poly(methyl acrylate) at the temperature corresponding to 13 K above the glass transition by monitoring the reorientation of single perylenediimide molecules doped into the films. The axial position of the dye molecules across the thickness of the film was determined with a resolution of 12 nm by analyzing astigmatic fluorescence images. The average relaxation times of the rotating molecules do not depend on the overall thickness of the film between 20 and 110 nm. The relaxation times also do not show any dependence on the axial position within the films for the film thickness between 70 and 110 nm. In addition to the rotating molecules we observed a fraction of spatially diffusing molecules and completely immobile molecules. These molecules indicate the presence of thin (<5 nm) high-mobility surface layer and low-mobility layer at the interface with the substrate. (Figure presented) © 2012 American Chemical Society.

MEMS-based thick film PZT vibrational energy harvester

DEFF Research Database (Denmark)

Lei, Anders; Xu, Ruichao; Thyssen, Anders

2011-01-01

We present a MEMS-based unimorph silicon/PZT thick film vibrational energy harvester with an integrated proof mass. We have developed a process that allows fabrication of high performance silicon based energy harvesters with a yield higher than 90%. The process comprises a KOH etch using a mechan......We present a MEMS-based unimorph silicon/PZT thick film vibrational energy harvester with an integrated proof mass. We have developed a process that allows fabrication of high performance silicon based energy harvesters with a yield higher than 90%. The process comprises a KOH etch using...... a mechanical front side protection of an SOI wafer with screen printed PZT thick film. The fabricated harvester device produces 14.0 μW with an optimal resistive load of 100 kΩ from 1g (g=9.81 m s-2) input acceleration at its resonant frequency of 235 Hz....

Investigation of top electrode for PZT thick films based MEMS sensors

DEFF Research Database (Denmark)

Hindrichsen, Christian Carstensen; Pedersen, Thomas; Kristiansen, Paw T.

2010-01-01

In this work processing of screen printed piezoelectric PZT thick films on silicon substrates is investigated for use in future MEMS devices. E-beam evaporated Al and Pt are patterned on PZT as a top electrode using a lift-off process with a line width down to 3 mu m. Three test structures are used...... to investigate the optimal thickness of the top electrode, the degradation of the piezoelectric properties of the PZT film in absence of a diffusion barrier layer and finally how to fabricate electrical interconnects down the edge of the PZT thick film. The roughness of the PZT is found to have a strong...... influence on the conductance of the top electrode influencing the optimal top electrode thickness. A 100 nm thick top electrode on the PZT thick film with a surface roughness of 273 nm has a 4.5 times higher resistance compared to a similar wire on a planar SiO2 surface which has a surface roughness of less...

Miniaturized, Planar Ion-selective Electrodes Fabricated by Means of Thick-film Technology

Directory of Open Access Journals (Sweden)

Robert Koncki

2006-04-01

Full Text Available Various planar technologies are employed for developing solid-state sensorshaving low cost, small size and high reproducibility; thin- and thick-film technologies aremost suitable for such productions. Screen-printing is especially suitable due to itssimplicity, low-cost, high reproducibility and efficiency in large-scale production. Thistechnology enables the deposition of a thick layer and allows precise pattern control.Moreover, this is a highly economic technology, saving large amounts of the used inks. Inthe course of repetitions of the film-deposition procedure there is no waste of material dueto additivity of this thick-film technology. Finally, the thick films can be easily and quicklydeposited on inexpensive substrates. In this contribution, thick-film ion-selective electrodesbased on ionophores as well as crystalline ion-selective materials dedicated forpotentiometric measurements are demonstrated. Analytical parameters of these sensors arecomparable with those reported for conventional potentiometric electrodes. All mentionedthick-film strip electrodes have been totally fabricated in only one, fully automated thick-film technology, without any additional manual, chemical or electrochemical steps. In allcases simple, inexpensive, commercially available materials, i.e. flexible, plastic substratesand easily cured polymer-based pastes were used.

Use of B{sub 2}O{sub 3} films grown by plasma-assisted atomic layer deposition for shallow boron doping in silicon

Energy Technology Data Exchange (ETDEWEB)

Kalkofen, Bodo, E-mail: bodo.kalkofen@ovgu.de; Amusan, Akinwumi A.; Bukhari, Muhammad S. K.; Burte, Edmund P. [Institute of Micro and Sensor Systems, Otto-von-Guericke University, Universitätsplatz 2, 39106 Magdeburg (Germany); Garke, Bernd [Institute for Experimental Physics, Otto-von-Guericke University, Universitätsplatz 2, 39106 Magdeburg (Germany); Lisker, Marco [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Gargouri, Hassan [SENTECH Instruments GmbH, Schwarzschildstraße 2, 12489 Berlin (Germany)

2015-05-15

Plasma-assisted atomic layer deposition (PALD) was carried for growing thin boron oxide films onto silicon aiming at the formation of dopant sources for shallow boron doping of silicon by rapid thermal annealing (RTA). A remote capacitively coupled plasma source powered by GaN microwave oscillators was used for generating oxygen plasma in the PALD process with tris(dimethylamido)borane as boron containing precursor. ALD type growth was obtained; growth per cycle was highest with 0.13 nm at room temperature and decreased with higher temperature. The as-deposited films were highly unstable in ambient air and could be protected by capping with in-situ PALD grown antimony oxide films. After 16 weeks of storage in air, degradation of the film stack was observed in an electron microscope. The instability of the boron oxide, caused by moisture uptake, suggests the application of this film for testing moisture barrier properties of capping materials particularly for those grown by ALD. Boron doping of silicon was demonstrated using the uncapped PALD B{sub 2}O{sub 3} films for RTA processes without exposing them to air. The boron concentration in the silicon could be varied depending on the source layer thickness for very thin films, which favors the application of ALD for semiconductor doping processes.

Thick-film effects in the oxidation and hydriding of zirconium alloys

International Nuclear Information System (INIS)

Johnson, A.B. Jr.

1989-08-01

One of the fundamental discoveries involving radiation effects on the oxidation of Zircaloy in low-oxygen aqueous environments is the influence of thick oxide films. Zircaloy oxidation rates in low-oxygen (hydrogen-rich) coolants initially proceed at relatively low rates, often almost uninfluenced by radiation. Marked upturns in oxidation rate have signaled the onset of radiation effects. The radiation effects appear to correlate with a threshold oxide thickness. Results of the test reactor experiments lead to formulation of the Thick-Film Hypothesis: beyond a threshold oxide thickness, radiolysis of water that infiltrates oxide cracks and pores controls the oxidation rate; radiation creates microenvironments inside the oxide film, producing highly oxidizing conditions, that are no longer suppressed by the coolant-borne hydrogen. Upturns in oxidation rate on high-exposure Zircaloy pressure tubes add confirmatory evidence for the thick-film effect. This paper summarizes the early evidence for thick-film behavior, including oxidation and hydriding trends, updates confirmatory evidence from Zircaloy reactor and fuel assembly components, and highlights other observations from the test reactor series that have potential fundamental significance to explanations of radiation effects on Zircaloy. 23 refs., 10 figs

A study on the evolution of dielectric function of ZnO thin films with decreasing film thickness

International Nuclear Information System (INIS)

Li, X. D.; Chen, T. P.; Liu, P.; Liu, Y.; Liu, Z.; Leong, K. C.

2014-01-01

Dielectric function, band gap, and exciton binding energies of ultrathin ZnO films as a function of film thickness have been obtained with spectroscopic ellipsometry. As the film thickness decreases, both real (ε 1 ) and imaginary (ε 2 ) parts of the dielectric function decrease significantly, and ε 2 shows a blue shift. The film thickness dependence of the dielectric function is shown related to the changes in the interband absorption, discrete-exciton absorption, and continuum-exciton absorption, which can be attributed to the quantum confinement effect on both the band gap and exciton binding energies

Structural, transport and microwave properties of 123/sapphire films: Thickness effect

Energy Technology Data Exchange (ETDEWEB)

Predtechensky, MR.; Smal, A.N.; Varlamov, Y.D. [Institute of Thermophysics, Novosibirsk (Russian Federation)] [and others

1994-12-31

The effect of thickness and growth conditions on the structure and microwave properties has been investigated for the 123/sapphire films. It has been shown that in the conditions of epitaxial growth and Al atoms do not diffuse from substrate into the film and the films with thickness up to 100nm exhibit the excellent DC properties. The increase of thickness of GdBaCuO films causes the formation of extended line-mesh defects and the increase of the surface resistance (R{sub S}). The low value of surface resistance R{sub S}(75GHz,77K)=20 mOhm has been obtained for the two layer YBaCuO/CdBaCuO/sapphire films.

Imaging and thickness measurement of amorphous intergranular films using TEM

International Nuclear Information System (INIS)

MacLaren, I.

2004-01-01

Fresnel fringe analysis is shown to be unreliable for grain boundaries in yttrium-doped alumina: the determined thicknesses do not agree well with those measured from high resolution transmission electron microscopy (HRTEM), the asymmetry between under- and overfocus is very large, and Fresnel fringes are sometimes shown at boundaries which contain no amorphous film. An alternative approach to the analysis of HRTEM images of grain boundary films is demonstrated: Fourier filtering is used to remove the lattice fringes from the image thereby significantly enhancing the visibility of the intergranular films. The apparent film thickness shows a discrepancy between measurements from the original HRTEM image and the filtered image. It was shown that fringe delocalisation and diffuseness of the amorphous/crystalline interfaces will lead to a significant underestimate of the thickness in unprocessed HRTEM images. In contrast to this, the average thickness can be much more accurately measured from the Fourier-filtered image, provided the boundary is oriented accurately edge-on

Comparative study of ITO and FTO thin films grown by spray pyrolysis

International Nuclear Information System (INIS)

Ait Aouaj, M.; Diaz, R.; Belayachi, A.; Rueda, F.; Abd-Lefdil, M.

2009-01-01

Tin doped indium oxide (ITO) and fluorine doped tin oxide (FTO) thin films have been prepared by one step spray pyrolysis. Both film types grown at 400 deg. C present a single phase, ITO has cubic structure and preferred orientation (4 0 0) while FTO exhibits a tetragonal structure. Scanning electron micrographs showed homogeneous surfaces with average grain size around 257 and 190 nm for ITO and FTO respectively. The optical properties have been studied in several ITO and FTO samples by transmittance and reflectance measurements. The transmittance in the visible zone is higher in ITO than in FTO layers with a comparable thickness, while the reflectance in the infrared zone is higher in FTO in comparison with ITO. The best electrical resistivity values, deduced from optical measurements, were 8 x 10 -4 and 6 x 10 -4 Ω cm for ITO (6% of Sn) and FTO (2.5% of F) respectively. The figure of merit reached a maximum value of 2.15 x 10 -3 Ω -1 for ITO higher than 0.55 x 10 -3 Ω -1 for FTO.

Fabrication and Characterization of PZT Thick Films for Sensing and Actuation

Directory of Open Access Journals (Sweden)

Kuo-Ching Kuo

2007-04-01

Full Text Available Lead Zirconate Titanate oxide (PZT thick films with thicknesses of up to 10 μmwere developed using a modified sol-gel technique. Usually, the film thickness is less than1 μm by conventional sol-gel processing, while the electrical charge accumulation whichreveals the direct effect of piezoelectricity is proportional to the film thickness and thereforerestricted. Two approaches were adopted to conventional sol-gel processing – precursorconcentration modulation and rapid thermal annealing. A 10 μm thick film was successfullyfabricated by coating 16 times via this technique. The thickness of each coating layer wasabout 0.6 μm and the morphology of the film was dense with a crack-free area as large as 16mm2. In addition, the structure, surface morphology and physical properties werecharacterized by X-ray diffraction (XRD, scanning electron microscopy (SEM and atomicforce microscopy (AFM and electrical performance. The dielectric constant and hysteresisloops were measured as electric characteristics. This study investigates the actuation andsensing performance of the vibrating structures with the piezoelectric thick film. Theactuation tests demonstrated that a 4 mm x 4 mm x 6.5 μm PZT film drove a 40 mm x 7 mmx 0.5 mm silicon beam as an actuator. Additionally, it generated an electrical signal of 60mVpp as a sensor, while vibration was input by a shaker. The frequencies of the first twomodes of the beam were compared with the theoretical values obtained by Euler-Bernoullibeam theory. The linearity of the actuation and sensing tests were also examined.

Thickness-dependent radiative properties of Y-Ba-Cu-O thin films

International Nuclear Information System (INIS)

Phelan, P.E.; Chen, G.; Tien, C.L.

1991-01-01

Some applications of high-temperature superconductors where their thermal radiative behavior is important, such as bolometers, optically-triggered switches and gates, and space-cooled electronics, required the superconductor to be in the form of a very thin film whose radiative behavior cannot be adequately represented by a semi-infinite analysis. Two properties of particular importance are the film absorptance and the combined film/substrate absorptance, which are crucial to the operation of many devices. This paper reports on calculations of the absorptance of superconducting-state Y-Ba-Cu-O films on MgO substrates which suggest that for film thicknesses less than about 50 nm, a decrease in the film thickness leads to an increase in both the film absorptance and the film/substrate absorptance. Furthermore, the film absorptance is maximum at some optimal value of film thickness. Assuming the film to be a smooth, continuous slab with a refractive index equal to that of the bulk Y-Ba-Cu-O is verified, at least in the normal state and for films as thin as 35 nm, by room-temperature reflectance and transmittance measurements

Engineering the mechanical properties of ultrabarrier films grown by atomic layer deposition for the encapsulation of printed electronics

International Nuclear Information System (INIS)

Bulusu, A.; Singh, A.; Kim, H.; Wang, C. Y.; Dindar, A.; Fuentes-Hernandez, C.; Kippelen, B.; Cullen, D.; Graham, S.

2015-01-01

Direct deposition of barrier films by atomic layer deposition (ALD) onto printed electronics presents a promising method for packaging devices. Films made by ALD have been shown to possess desired ultrabarrier properties, but face challenges when directly grown onto surfaces with varying composition and topography. Challenges include differing nucleation and growth rates across the surface, stress concentrations from topography and coefficient of thermal expansion mismatch, elastic constant mismatch, and particle contamination that may impact the performance of the ALD barrier. In such cases, a polymer smoothing layer may be needed to coat the surface prior to ALD barrier film deposition. We present the impact of architecture on the performance of aluminum oxide (Al 2 O 3 )/hafnium oxide (HfO 2 ) ALD nanolaminate barrier films deposited on fluorinated polymer layer using an optical calcium (Ca) test under damp heat. It is found that with increasing polymer thickness, the barrier films with residual tensile stress are prone to cracking resulting in rapid failure of the Ca sensor at 50 °C/85% relative humidity. Inserting a SiN x layer with residual compressive stress between the polymer and ALD layers is found to prevent cracking over a range of polymer thicknesses with more than 95% of the Ca sensor remaining after 500 h of testing. These results suggest that controlling mechanical properties and film architecture play an important role in the performance of direct deposited ALD barriers

Engineering the mechanical properties of ultrabarrier films grown by atomic layer deposition for the encapsulation of printed electronics

Energy Technology Data Exchange (ETDEWEB)

Bulusu, A.; Singh, A.; Kim, H. [Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Wang, C. Y.; Dindar, A.; Fuentes-Hernandez, C.; Kippelen, B. [School of Electrical and Computer Engineering, Georgia Institute of Technology, and Center for Organic Photonics and Electronics, Atlanta, Georgia 30332 (United States); Cullen, D. [Oak Ridge National Laboratory, P.O. Box 2008 MS-6064, Oak Ridge, Tennessee 37831 (United States); Graham, S., E-mail: sgraham@gatech.edu [Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Oak Ridge National Laboratory, P.O. Box 2008 MS-6064, Oak Ridge, Tennessee 37831 (United States)

2015-08-28

Direct deposition of barrier films by atomic layer deposition (ALD) onto printed electronics presents a promising method for packaging devices. Films made by ALD have been shown to possess desired ultrabarrier properties, but face challenges when directly grown onto surfaces with varying composition and topography. Challenges include differing nucleation and growth rates across the surface, stress concentrations from topography and coefficient of thermal expansion mismatch, elastic constant mismatch, and particle contamination that may impact the performance of the ALD barrier. In such cases, a polymer smoothing layer may be needed to coat the surface prior to ALD barrier film deposition. We present the impact of architecture on the performance of aluminum oxide (Al{sub 2}O{sub 3})/hafnium oxide (HfO{sub 2}) ALD nanolaminate barrier films deposited on fluorinated polymer layer using an optical calcium (Ca) test under damp heat. It is found that with increasing polymer thickness, the barrier films with residual tensile stress are prone to cracking resulting in rapid failure of the Ca sensor at 50 °C/85% relative humidity. Inserting a SiN{sub x} layer with residual compressive stress between the polymer and ALD layers is found to prevent cracking over a range of polymer thicknesses with more than 95% of the Ca sensor remaining after 500 h of testing. These results suggest that controlling mechanical properties and film architecture play an important role in the performance of direct deposited ALD barriers.

Surface and Interface Properties of 10–12 Unit Cells Thick Sputter Deposited Epitaxial CeO2 Films

Directory of Open Access Journals (Sweden)

L. V. Saraf

2008-01-01

Full Text Available Ultrathin and continuous epitaxial films with relaxed lattice strain can potentially maintain more of its bulk physical and chemical properties and are useful as buffer layers. We study surface, interface, and microstructural properties of ultrathin (∼10–12 unit cells thick epitaxial ceria films grown on single crystal YSZ substrates. The out-of -plane and in-plane lattice parameters indicate relaxation in the continuous film due to misfit dislocations seen by high-resolution transmission electron microscopy (HRTEM and substrate roughness of ∼1-2 unit cells, confirmed by atomic force microscopy and HRTEM. A combination of secondary sputtering, lattice mismatch, substrate roughness, and surface reduction creating secondary phase was likely the cause of surface roughness which should be reduced to a minimum level for effective use of it as buffer layers.

Nanocrystalline magnetite thin films grown by dual ion-beam sputtering

International Nuclear Information System (INIS)

Prieto, Pilar; Ruiz, Patricia; Ferrer, Isabel J.; Figuera, Juan de la; Marco, José F.

2015-01-01

Highlights: • We have grown tensile and compressive strained nanocrystalline magnetite thin films by dual ion beam sputtering. • The magnetic and thermoelectric properties can be controlled by the deposition conditions. • The magnetic anisotropy depends on the crystalline grain size. • The thermoelectric properties depend on the type of strain induced in the films. • In plane uniaxial magnetic anisotropy develops in magnetite thin films with grain sizes ⩽20 nm. - Abstract: We have explored the influence of an ion-assisted beam in the thermoelectric and magnetic properties of nanocrystalline magnetite thin films grown by ion-beam sputtering. The microstructure has been investigated by XRD. Tensile and compressive strained thin films have been obtained as a function of the parameters of the ion-assisted beam. The evolution of the in-plane magnetic anisotropy was attributed to crystalline grain size. In some films, magneto-optical Kerr effect measurements reveal the existence of uniaxial magnetic anisotropy induced by the deposition process related with a small grain size (⩽20 nm). Isotropic magnetic properties have observed in nanocrystalline magnetite thin film having larger grain sizes. The largest power factor of all the films prepared (0.47 μW/K 2 cm), obtained from a Seebeck coefficient of −80 μV/K and an electrical resistivity of 13 mΩ cm, is obtained in a nanocrystalline magnetite thin film with an expanded out-of-plane lattice and with a grain size ≈30 nm

Thickness of residual wetting film in liquid-liquid displacement

Science.gov (United States)

Beresnev, Igor; Gaul, William; Vigil, R. Dennis

2011-08-01

Core-annular flow is common in nature, representing, for example, how streams of oil, surrounded by water, move in petroleum reservoirs. Oil, typically a nonwetting fluid, tends to occupy the middle (core) part of a channel, while water forms a surrounding wall-wetting film. What is the thickness of the wetting film? A classic theory has been in existence for nearly 50 years offering a solution, although in a controversial manner, for moving gas bubbles. On the other hand, an acceptable, experimentally verified theory for a body of one liquid flowing in another has not been available. Here we develop a hydrodynamic, testable theory providing an explicit relationship between the thickness of the wetting film and fluid properties for a blob of one fluid moving in another, with neither phase being gas. In its relationship to the capillary number Ca, the thickness of the film is predicted to be proportional to Ca2 at lower Ca and to level off at a constant value of ˜20% the channel radius at higher Ca. The thickness of the film is deduced to be approximately unaffected by the viscosity ratio of the fluids. We have conducted our own laboratory experiments and compiled experimental data from other studies, all of which are mutually consistent and confirm the salient features of the theory. At the same time, the classic law, originally deduced for films surrounding moving gas bubbles but often believed to hold for liquids as well, fails to explain the observations.

Morphology and photoresponse of crystalline antimony film grown on mica by physical vapor deposition

Directory of Open Access Journals (Sweden)

Shafa Muhammad

2016-09-01

Full Text Available Antimony is a promising material for the fabrication of photodetectors. This study deals with the growth of a photosensitive thin film by the physical vapor deposition (PVD of antimony onto mica surface in a furnace tube. The geometry of the grown structures was studied via scanning electron microscopy (SEM, X-ray diffraction (XRD, energy-dispersive X-ray spectroscopy (EDX and elemental diffraction analysis. XRD peaks of the antimony film grown on mica mostly matched with JCPDF Card. The formation of rhombohedral crystal structures in the film was further confirmed by SEM micrographs and chemical composition analysis. The Hall measurements revealed good electrical conductivity of the film with bulk carrier concentration of the order of 1022 Ω·cm-3 and mobility of 9.034 cm2/Vs. The grown film was successfully tested for radiation detection. The photoresponse of the film was evaluated using its current-voltage characteristics. These investigations revealed that the photosensitivity of the antimony film was 20 times higher than that of crystalline germanium.

Comparison of different methods for measuring the passive film thickness on metals

International Nuclear Information System (INIS)

Benoit, Marie; Bataillon, Christian; Gwinner, Benoit; Miserque, Frédéric; Orazem, Mark E.; Sánchez-Sánchez, Carlos M.; Tribollet, Bernard; Vivier, Vincent

2016-01-01

Highlights: • In situ EIS and ex situ XPS were used for the characterization of zirconium oxide films. • The film thicknesses can be obtained from the analysis of a single EIS diagram. • A convenient graphical method to extract film properties is proposed. - Abstract: In situ electrochemical impedance spectroscopy (EIS) and ex situ X-ray photoelectron spectroscopy (XPS) measurements on electrogenerated zirconium oxide films on zirconium (Zr/ZrO_2) were used to quantify the oxide film thickness and resistivity profiles through the oxide. The EIS analysis presented here takes advantage of the high-frequency domain at which the constant-phase element (CPE) behavior of the oxide film reverts to a capacitive response and the Cole-Cole representations of the complex capacitance to extract the high-frequency capacitance of the oxide film without reference to the nature of the time-constant distribution within the oxide film. The film thickness of the ZrO_2 samples measured from the high-frequency capacitance of EIS were in good agreement with the thickness obtained from XPS. Moreover, the EIS analysis presented is based on the use of the integral solution of the power law model, which allows to obtain in one single EIS experiment, both the film thickness and the resistivity profile in the ZrO_2 film. This work suggests a convenient graphical method to extract film properties and serves to validate a key assumption of the power-law model for interpretation of CPE parameters in terms of physical properties.

Application of β plastic film thickness gauge in automatic production of agricultural film

International Nuclear Information System (INIS)

Liu Longzhi; Guo Juhao

1996-01-01

The author briefly explains the importance of agricultural film at home, and mainly explains the measuring principles of plastic film thickness, the design of β detector, the temperature compensation technology and the design of automatic control device

The determination of the pressure-viscosity coefficient of a lubricant through an accurate film thickness formula and accurate film thickness measurements : part 2 : high L values

NARCIS (Netherlands)

Leeuwen, van H.J.

2011-01-01

The pressure-viscosity coefficient of a traction fluid is determined by fitting calculation results on accurate film thickness measurements, obtained at different speeds, loads, and temperatures. Through experiments, covering a range of 5.6 film thickness values are

Angular multiplexing holograms of four images recorded on photopolymer films with recording-film-thickness-dependent holographic characteristics

Science.gov (United States)

Osabe, Keiichi; Kawai, Kotaro

2017-03-01

In this study, angular multiplexing hologram recording photopolymer films were studied experimentally. The films contained acrylamide as a monomer, eosin Y as a sensitizer, and triethanolamine as a promoter in a polyvinyl alcohol matrix. In order to determine the appropriate thickness of the photopolymer films for angular multiplexing, photopolymer films with thicknesses of 29-503 μm were exposed to two intersecting beams of a YVO laser at a wavelength of 532 nm to form a holographic grating with a spatial frequency of 653 line/mm. The diffraction efficiencies as a function of the incident angle of reconstruction were measured. A narrow angular bandwidth and high diffraction efficiency are required for angular multiplexing; hence, we define the Q value, which is the diffraction efficiency divided by half the bandwidth. The Q value of the films depended on the thickness of the films, and was calculated based on the measured diffraction efficiencies. The Q value of a 297-μm-thick film was the highest of the all films. Therefore, the angular multiplexing experiments were conducted using 300-μm-thick films. In the angular multiplexing experiments, the object beam transmitted by a square aperture was focused by a Fourier transform lens and interfered with a reference beam. The maximum order of angular multiplexing was four. The signal intensity that corresponds to the squared-aperture transmission and the noise intensity that corresponds to transmission without the square aperture were measured. The signal intensities decreased as the order of angular multiplexing increased, and the noise intensities were not dependent on the order of angular multiplexing.

Planar Zeolite Film-Based Potentiometric Gas Sensors Manufactured by a Combined Thick-Film and Electroplating Technique

Science.gov (United States)

Marr, Isabella; Reiß, Sebastian; Hagen, Gunter; Moos, Ralf

2011-01-01

Zeolites are promising materials in the field of gas sensors. In this technology-oriented paper, a planar setup for potentiometric hydrocarbon and hydrogen gas sensors using zeolites as ionic sodium conductors is presented, in which the Pt-loaded Na-ZSM-5 zeolite is applied using a thick-film technique between two interdigitated gold electrodes and one of them is selectively covered for the first time by an electroplated chromium oxide film. The influence of the sensor temperature, the type of hydrocarbons, the zeolite film thickness, and the chromium oxide film thickness is investigated. The influence of the zeolite on the sensor response is briefly discussed in the light of studies dealing with zeolites as selectivity-enhancing cover layers. PMID:22164042

Planar Zeolite Film-Based Potentiometric Gas Sensors Manufactured by a Combined Thick-Film and Electroplating Technique

Directory of Open Access Journals (Sweden)

Gunter Hagen

2011-08-01

Full Text Available Zeolites are promising materials in the field of gas sensors. In this technology-oriented paper, a planar setup for potentiometric hydrocarbon and hydrogen gas sensors using zeolites as ionic sodium conductors is presented, in which the Pt-loaded Na-ZSM-5 zeolite is applied using a thick-film technique between two interdigitated gold electrodes and one of them is selectively covered for the first time by an electroplated chromium oxide film. The influence of the sensor temperature, the type of hydrocarbons, the zeolite film thickness, and the chromium oxide film thickness is investigated. The influence of the zeolite on the sensor response is briefly discussed in the light of studies dealing with zeolites as selectivity-enhancing cover layers.

Influence of film thickness on structural, optical, and electrical properties of spray deposited antimony doped SnO{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Yadav, Abhijit A., E-mail: aay_physics@yahoo.co.in

2015-09-30

Transparent conducting antimony doped SnO{sub 2} thin films with varying thickness were deposited by chemical spray pyrolysis technique from non-aqueous solvent Propan-2-ol. The effect of film thickness on the properties of antimony doped SnO{sub 2} thin films have been studied. X-ray diffraction measurements showed tetragonal crystal structure of as-deposited antimony doped SnO{sub 2} films irrespective of film thickness. The surface morphology of antimony doped SnO{sub 2} thin film is spherical with the continuous distribution of grains. Electrical and optical properties were investigated by Hall Effect and optical measurements. The average optical transmittance of films decreased from 89% to 73% within the visible range (350–850 nm) with increase in film thickness. The minimum value of sheet resistance observed is 4.81 Ω/cm{sup 2}. The lowest resistivity found is 3.76 × 10{sup −4} Ω cm at 660 nm film thickness. - Highlights: • Effect of film thickness on the properties of antimony doped SnO{sub 2} thin films • Crystalline size in the range of 34–37 nm • Average transmittance decreased from 89% to 73% in the visible region. • Minimum sheet resistance of 4.81 Ω/cm{sup 2} • Lowest resistivity is found to be 3.76 × 10{sup −4} Ω cm at 660 nm film thickness.

Screen-printed piezoceramic thick films for miniaturised devices

DEFF Research Database (Denmark)

Lou-Moeller, R.; Hindrichsen, Christian Carstensen; Thamdrup, Lasse Højlund

2007-01-01

machining. On the other hand, the process of screen printing thick films involves potential problems of thermal matching and chemical compatibility at the processing temperatures between the functional film, the substrate and the electrodes. As an example of such a miniaturised device, a MEMS accelerometer...

Strong band edge luminescence from InN films grown on Si substrates by electron cyclotron resonance-assisted molecular beam epitaxy

International Nuclear Information System (INIS)

Yodo, Tokuo; Yona, Hiroaki; Ando, Hironori; Nosei, Daiki; Harada, Yoshiyuki

2002-01-01

We observed strong band edge luminescence at 8.5-200 K from 200-880 nm thick InN films grown on 10 nm thick InN buffer layers on Si(001) and Si(111) substrates by electron cyclotron resonance-assisted molecular beam epitaxy. The InN film on the Si(001) substrate exhibited strong band edge photoluminescence (PL) emission at 1.814 eV at 8.5 K, tentatively assigned as donor to acceptor pair [DAP (α-InN)] emission from wurtzite-InN (α-InN) crystal grains, while those on Si(111) showed other stronger band edge PL emissions at 1.880, 2.081 and 2.156 eV, tentatively assigned as donor bound exciton [D 0 X(α-InN)] from α-InN grains, DAP (β-InN) and D 0 X (β-InN) emissions from zinc blende-InN (β-InN) grains, respectively

Influence of cement film thickness on the retention of implant-retained crowns.

Science.gov (United States)

Mehl, Christian; Harder, Sönke; Steiner, Martin; Vollrath, Oliver; Kern, Matthias

2013-12-01

The main goal of this study was to establish a new, high precision procedure to evaluate the influence of cement film thickness on the retention of cemented implant-retained crowns. Ninety-six tapered titanium abutments (6° taper, 4.3 mm diameter, Camlog) were shortened to 4 mm. Computer-aided design was used to design the crowns, and selective laser sintering, using a cobalt-chromium alloy, was used to produce the crowns. This method used a focused high-energy laser beam to fuse a localized region of metal powder to build up the crowns gradually. Before cementing, preset cement film thicknesses of 15, 50, 80, or 110 μm were established. Glass ionomer, polycarboxylate, or resin cements were used for cementation. After 3 days storage in demineralized water, the retention of the crowns was measured in tension using a universal testing machine. The cement film thicknesses could be achieved with a high level of precision. Interactions between the factors cement and cement film thickness could be found (p ≤ 0.001). For all cements, crown retention decreased significantly between a cement film thickness of 15 and 50 μm (p ≤ 0.001). At 15 μm cement film thickness, the resin cement was the most retentive cement, followed by the polycarboxylate and then the glass ionomer cement (p ≤ 0.05). The results suggest that cement film thickness has an influence on the retentive strength of cemented implant-retained crowns. © 2013 by the American College of Prosthodontists.

Photosensitivity of nanocrystalline ZnO films grown by PLD

International Nuclear Information System (INIS)

Ayouchi, R.; Bentes, L.; Casteleiro, C.; Conde, O.; Marques, C.P.; Alves, E.; Moutinho, A.M.C.; Marques, H.P.; Teodoro, O.; Schwarz, R.

2009-01-01

We have studied the properties of ZnO thin films grown by laser ablation of ZnO targets on (0 0 0 1) sapphire (Al 2 O 3 ), under substrate temperatures around 400 deg. C. The films were characterized by different methods including X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and atomic force microscopy (AFM). XPS analysis revealed that the films are oxygen deficient, and XRD analysis with θ-2θ scans and rocking curves indicate that the ZnO thin films are highly c-axis oriented. All the films are ultraviolet (UV) sensitive. Sensitivity is maximum for the films deposited at lower temperature. The films deposited at higher temperatures show crystallite sizes of typically 500 nm, a high dark current and minimum photoresponse. In all films we observe persistent photoconductivity decay. More densely packed crystallites and a faster decay in photocurrent is observed for films deposited at lower temperature

Fabrication of thick superconducting films by decantation

Directory of Open Access Journals (Sweden)

Julián Betancourt M.

1991-07-01

Full Text Available We have found superconducting behavior in thick films fabricated by decantation. In this paper we present the experimental method and results obtained using commercial copper substrates.

Properties of conductive thick-film inks

Science.gov (United States)

Holtze, R. F.

1972-01-01

Ten different conductive inks used in the fabrication of thick-film circuits were evaluated for their physical and handling properties. Viscosity, solid contents, and spectrographic analysis of the unfired inks were determined. Inks were screened on ceramic substrates and fired for varying times at specified temperatures. Selected substrates were given additional firings to simulate the heat exposure received if thick-film resistors were to be added to the same substrate. Data are presented covering the (1) printing characteristics, (2) solderability using Sn-63 and also a 4 percent silver solder, (3) leach resistance, (4) solder adhesion, and (5) wire bonding properties. Results obtained using different firing schedules were compared. A comparison was made between the various inks showing general results obtained for each ink. The changes in firing time or the application of a simulated resistor firing had little effect on the properties of most inks.

Optimization of phantom backscatter thickness and lateral scatter volume for radiographic film dosimetry

International Nuclear Information System (INIS)

Srivastava, R.P.; De Wagter, C.

2012-01-01

The aim of this study is to determine the optimal backscatter thickness and lateral phantom dimension beyond the irradiated volume for the dosimetric verification with radiographic film when applying large field sizes. Polystyrene and Virtual Water™ phantoms were used to study the influence of the phantom backscatter thickness. EDR2 and XV films were used in 6 and 18 MV photon beams. The results show 11.4% and 6.4% over-response of the XV2 film when compared to the ion chamber for 6 MV 30×30 and 10×10 cm 2 field sizes, respectively, when the phantom backscatter thickness is 5 cm. For the same setup, measurements with EDR2 films indicate 8.5% and 1.7% over-response. The XV2 film response in the polystyrene phantom is about 2.0% higher than in the Virtual Water™ phantom for the 6 MV beam and 20 cm backscatter thickness. Similar results were obtained for EDR2 film. In the lateral scatter study, film response was nearly constant within 5 cm of lateral thickness and it increases when lateral thickness increases due to more multiple scatter of low energy photons. The backscatter thickness of the phantom should be kept below 7 cm for the accuracy of the film dosimetry. The lateral extension of the phantom should not be more than 5 cm from the field boundary in case of large irradiated volumes.

Thickness and Nb-doping effects on ferro- and piezoelectric properties of highly a-axis-oriented Nb-doped Pb(Zr0.3Ti0.7)O3 films

Science.gov (United States)

Zhu, Zhi-Xiang; Ruangchalermwong, C.; Li, Jing-Feng

2008-09-01

Tetragonal Nb-doped Pb(Zr0.3Ti0.7)O3 (PNZT) films with a lead oxide seeding layer were deposited on the Pt(111)/Ti/SiO2/Si(100) substrates by sol-gel processing. The as-grown PNZT films with thicknesses ranging from about 0.08 to 0.78 μm show highly a-axis preferential orientation, and their ferroelectric and piezoelectric properties improved with increasing film thickness. Due to the combined effects of Nb doping and a-axis texturing as well as reduced substrate constraint, a high d33 constant up to 196 pm/V was obtained for PNZT film at 0.78 μm in addition to a large remnant polarization of 69 μC/cm2. This well a-axis-oriented PNZT films on platinized Si with a high piezoresponse are suitable for the fabrication of microelectromechanical devices.

Metallic oxide switches using thick film technology

Science.gov (United States)

Patel, D. N.; Williams, L., Jr.

1974-01-01

Metallic oxide thick film switches were processed on alumina substrates using thick film technology. Vanadium pentoxide in powder form was mixed with other oxides e.g., barium, strontium copper and glass frit, ground to a fine powder. Pastes and screen printable inks were made using commercial conductive vehicles and appropriate thinners. Some switching devices were processed by conventional screen printing and firing of the inks and commercial cermet conductor terminals on 96% alumina substrates while others were made by applying small beads or dots of the pastes between platinum wires. Static, and dynamic volt-ampere, and pulse tests indicate that the switching and self-oscillatory characteristics of these devices could make them useful in memory element, oscillator, and automatic control applications.

Persistent quantum-size effect in aluminum films up to twelve atoms thick

International Nuclear Information System (INIS)

Boettger, J.C.

1996-01-01

Total energies and work functions have been calculated for unrelaxed, free-standing Al(111) films, 1 endash 12 layers thick, using the all-electron, full-potential linear combination of Gaussian-type orbitals endash fitting-function technique. The work function exhibits a significant quantum-size effect (at least 0.1 eV) over the entire range of thickness considered. This result contradicts an old prediction that the work function of an Al(111) N-layer film will converge to within a few hundredths of an eV by N=6. The present result, which is consistent with earlier jellium calculations, demonstrates the risk of mistaking an accidental coincidence of work functions for two films, differing in thickness by one layer, for a true convergence with respect to thickness. The implications for thin-film calculations of surface properties are discussed. A linear fit to the film binding energy vs thickness is used to extract the Al(111) surface energy (0.45 eV) and the binding energy of bulk Al (4.06 eV). copyright 1996 The American Physical Society

Mems-based pzt/pzt bimorph thick film vibration energy harvester

DEFF Research Database (Denmark)

Xu, Ruichao; Lei, Anders; Dahl-Petersen, Christian

2011-01-01

We describe fabrication and characterization of a significantly improved version of a MEMS-based PZT/PZT thick film bimorph vibration energy harvester with an integrated silicon proof mass. The main advantage of bimorph vibration energy harvesters is that strain energy is not lost in mechanical...... support materials since only PZT is strained, and thus it has a potential for significantly higher output power. An improved process scheme for the energy harvester resulted in a robust fabrication process with a record high fabrication yield of 98.6%. Moreover, the robust fabrication process allowed...... a high pressure treatment of the screen printed PZT thick films prior to sintering, improving the PZT thick film performance and harvester power output reaches 37.1 μW at 1 g....

Correlation of Gear Surface Fatigue Lives to Lambda Ratio (Specific Film Thickness)

Science.gov (United States)

Krantz, Timothy Lewis

2013-01-01

The effect of the lubrication regime on gear performance has been recognized, qualitatively, for decades. Often the lubrication regime is characterized by the specific film thickness being the ratio of lubricant film thickness to the composite surface roughness. Three studies done at NASA to investigate gearing pitting life are revisited in this work. All tests were done at a common load. In one study, ground gears were tested using a variety of lubricants that included a range of viscosities, and therefore the gears operated with differing film thicknesses. In a second and third study, the performance of gears with ground teeth and superfinished teeth were assessed. Thicker oil films provided longer lives as did improved surface finish. These datasets were combined into a common dataset using the concept of specific film thickness. This unique dataset of more 258 tests provides gear designers with some qualitative information to make gear design decisions.

The research of device for measuring film thickness of intelligent coating machine

Directory of Open Access Journals (Sweden)

Wang Wanjun

2015-01-01

Full Text Available Ion beam sputtering machine uses computer to real time monitor the change of film thickness in the preparation process of soft X ray multilayer element fabrication. It solves the problems of uneven film thickness and too thick film thickness and so on, which exist in the original preparation process. The high-precision quartz crystal converts film thickness measurement into frequency measurement. The equal precision frequency meter based on FPGA measures the frequency. It can reduce the signal delay and interference signal of discrete components, accordingly improving the accuracy of measurement. Then it sents the count value to the host computer through the single chip microcomputer serial port. It calculates and displays the value by the GUI of LabVIEW. The experimental results show that, the relative measurement error can be decreased to 1/10, i.e., the measurement accuracy can be improved by more than ten times.

Effect of substrate temperature on the structure of amorphous oxygenated hydrocarbon films grown with a pulsed supersonic methane plasma flow

Energy Technology Data Exchange (ETDEWEB)

Fedoseeva, Yu. V., E-mail: fedoseeva@niic.nsc.ru [Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Pozdnyakov, G.A. [Khristianovich Institute of Theoretical and Applied Mechanics, SB RAS, Novosibirsk 630090 (Russian Federation); Okotrub, A.V.; Kanygin, M.A. [Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Nastaushev, Yu. V. [Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk 630090 (Russian Federation); Vilkov, O.Y. [St. Petersburg State University, St. Petersburg 198504 (Russian Federation); Bulusheva, L.G. [Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation)

2016-11-01

Highlights: • A deposition of supersonic methane plasma flow on silicon substrate produces amorphous oxygenated hydrocarbon (CO{sub x}H{sub y}) film. • The thickness, composition, and wettability of the film depend on the substrate temperature. • A rise of the substrate temperature from 500 to 700 °C promotes the sp{sup 3}-hybridization carbon formation. - Abstract: Since amorphous oxygenated hydrocarbon (CO{sub x}H{sub y}) films are promising engineering materials a study of the structure and composition of the films depending on the conditions of synthesis is important for controlling of their physicochemical properties. Here, we used the methods of scanning and transmission electron microscopy, X-ray photoelectron, near-edge X-ray absorption fine structure, Fourier transform infrared and Raman spectroscopy to reveal changes in the chemical connectivity of CO{sub x}H{sub y} films grown on silicon substrates heated to 300, 500, and 700 °C using a supersonic flow of methane plasma. It was found that the CO{sub x}H{sub y} films, deposited at 300 and 500 °C, were mainly composed of the sp{sup 2}-hybridized carbon areas with various oxygen species. A rise of the substrate temperature caused an increase of the portion of tetrahedral carbon atoms as well as carboxyl and hydroxyl groups. With growth of the substrate temperature, the film thickness reduced monotonically from 400 to 180 nm, while the film adhesion improved substantially. The films, deposited at lower temperatures, showed high hydrophilicity due to porosity and presence of oxygenated groups both at the surface and in the bulk.

High quality TmIG films with perpendicular magnetic anisotropy grown by sputtering

Science.gov (United States)

Wu, C. N.; Tseng, C. C.; Yeh, S. L.; Lin, K. Y.; Cheng, C. K.; Fanchiang, Y. T.; Hong, M.; Kwo, J.

Ferrimagnetic thulium iron garnet (TmIG) films grown on gadolinium gallium garnet substrates recently showed stress-induced perpendicular magnetic anisotropy (PMA), attractive for realization of quantum anomalous Hall effect (QAHE) of topological insulator (TI) films via the proximity effect. Moreover, current induced magnetization switching of Pt/TmIG has been demonstrated for the development of room temperature (RT) spintronic devices. In this work, high quality TmIG films (about 25nm) were grown by sputtering at RT followed by post-annealing. We showed that the film composition is tunable by varying the growth parameters. The XRD results showed excellent crystallinity of stoichiometric TmIG films with an out-of-plane lattice constant of 1.2322nm, a narrow film rocking curve of 0.017 degree, and a film roughness of 0.2 nm. The stoichiometric films exhibited PMA and the saturation magnetization at RT was 109 emu/cm3 (RT bulk value 110 emu/cm3) with a coercive field of 2.7 Oe. In contrast, TmIG films of Fe deficiency showed in-plane magnetic anisotropy. The high quality sputtered TmIG films will be applied to heterostructures with TIs or metals with strong spin-orbit coupling for novel spintronics.

CdO Doped Indium Oxide Thick Film as a Low Temperature H2S Gas Sensor

Directory of Open Access Journals (Sweden)

D. N. CHAVAN

2011-06-01

Full Text Available The thick films of AR grade In2O3 were prepared by standard screen-printing technique. The gas sensing performance of thick film was tested for various gases. It showed maximum gas response to ethanol vapor at 350 oC for 80 ppm. To improve the gas response and selectivity of the film towards a particular gas, In2O3 thick films were modified by dipping them in an aqueous solution of 0.1 M CdCl2 for different intervals of time. The surface modified (10 min In2O3 thick film showed maximum response to H2S gas (10 ppm than pure In2O3 thick film at 150 oC. Cadmium oxide on the surface of the film shifts the gas response from ethanol vapor to H2S gas. A systematic study of sensing performance of the thick films indicates the key role played by cadmium oxide on the surface of thick films. The selectivity, gas response and recovery time of the thick films were measured and presented.

Hydroxyapatite screen-printed thick films: optical and electrical properties

International Nuclear Information System (INIS)

Silva, C.C.; Rocha, H.H.B.; Freire, F.N.A.; Santos, M.R.P.; Saboia, K.D.A.; Goes, J.C.; Sombra, A.S.B.

2005-01-01

In this paper, we did a study on the structural and electrical properties of bioceramic hydroxiapatite (HA) thick films. The films were prepared in two layers using the screen-printing technique on Al 2 O 3 substrates. Mechanical alloying has been used successfully to produce nanocrystalline powders of hydroxyapatite to be used in the films. We also look for the effect of the grain size of the HA in the final properties of the film. The samples were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), infrared and Raman scattering spectroscopy and electrical measurements. We did a study of the dielectric permittivity and the loss of the films in the radio-frequency of the spectra. The X-ray diffraction patterns of the films indicate that all the peaks associated to HA phase is present in the films. One can notice that, for all the films there is a decrease of the DC (dielectric constant) with the increase of the frequency. The values of the dielectric constant of the films are in between 4 and 9 (at 1 kHz), as a function of the flux concentration. The loss is decreasing as we increase the frequency for all the films. These results strongly suggest that the screen-printing HA thick films are good candidates for applications in biocompatible coatings of implant materials

Hydroxyapatite screen-printed thick films: optical and electrical properties

Energy Technology Data Exchange (ETDEWEB)

Silva, C.C. [Laboratorio de Telecomunicaco-tilde es e Ciencia e Engenharia de Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Caixa Postal 6030, 60455-760 Fortaleza, Ceara (Brazil); Rocha, H.H.B. [Laboratorio de Telecomunicaco-tilde es e Ciencia e Engenharia de Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Caixa Postal 6030, 60455-760 Fortaleza, Ceara (Brazil); Freire, F.N.A. [Departamento de Quimica Orga-circumflex nica e Inorga-circumflex nica-UFC, Caixa Postal 6030, CEP 60455-760, Fortaleza, Ceara (Brazil); Santos, M.R.P. [Laboratorio de Telecomunicaco-tilde es e Ciencia e Engenharia de Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Caixa Postal 6030, 60455-760 Fortaleza, Ceara (Brazil); Saboia, K.D.A. [Laboratorio de Telecomunicaco-tilde es e Ciencia e Engenharia de Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Caixa Postal 6030, 60455-760 Fortaleza, Ceara (Brazil); Goes, J.C. [Laboratorio de Telecomunicaco-tilde es e Ciencia e Engenharia de Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Caixa Postal 6030, 60455-760 Fortaleza, Ceara (Brazil); Sombra, A.S.B. [Laboratorio de Telecomunicaco-tilde es e Ciencia e Engenharia de Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Caixa Postal 6030, 60455-760 Fortaleza, Ceara (Brazil)]. E-mail: sombra@fisica.ufc.br

2005-07-15

In this paper, we did a study on the structural and electrical properties of bioceramic hydroxiapatite (HA) thick films. The films were prepared in two layers using the screen-printing technique on Al{sub 2}O{sub 3} substrates. Mechanical alloying has been used successfully to produce nanocrystalline powders of hydroxyapatite to be used in the films. We also look for the effect of the grain size of the HA in the final properties of the film. The samples were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), infrared and Raman scattering spectroscopy and electrical measurements. We did a study of the dielectric permittivity and the loss of the films in the radio-frequency of the spectra. The X-ray diffraction patterns of the films indicate that all the peaks associated to HA phase is present in the films. One can notice that, for all the films there is a decrease of the DC (dielectric constant) with the increase of the frequency. The values of the dielectric constant of the films are in between 4 and 9 (at 1 kHz), as a function of the flux concentration. The loss is decreasing as we increase the frequency for all the films. These results strongly suggest that the screen-printing HA thick films are good candidates for applications in biocompatible coatings of implant materials.

Thick-Film and LTCC Passive Components for High-Temperature Electronics

Directory of Open Access Journals (Sweden)

A. Dziedzic

2013-04-01

Full Text Available At this very moment an increasing interest in the field of high-temperature electronics is observed. This is a result of development in the area of wide-band semiconductors’ engineering but this also generates needs for passives with appropriate characteristics. This paper presents fabrication as well as electrical and stability properties of passive components (resistors, capacitors, inductors made in thick-film or Low-Temperature Co-fired Ceramics (LTCC technologies fulfilling demands of high-temperature electronics. Passives with standard dimensions usually are prepared by screen-printing whereas combination of standard screen-printing with photolithography or laser shaping are recommenced for fabrication of micropassives. Attainment of proper characteristics versus temperature as well as satisfactory long-term high-temperature stability of micropassives is more difficult than for structures with typical dimensions for thick-film and LTCC technologies because of increase of interfacial processes’ importance. However it is shown that proper selection of thick-film inks together with proper deposition method permit to prepare thick-film micropassives (microresistors, air-cored microinductors and interdigital microcapacitors suitable for the temperature range between 150°C and 400°C.

Gas Sensing Performance of Pure and Modified BST Thick Film Resistor

Directory of Open Access Journals (Sweden)

G. H. JAIN

2008-04-01

Full Text Available Barium Strontium Titanate (BST-(Ba0.87Sr0.13TiO3 ceramic powder was prepared by mechanochemical process. The thick films of different thicknesses of BST were prepared by screen-printing technique and gas-sensing performance of these films was tested for various gases. The films showed highest response and selectivity to ammonia gas. The pure BST film was surface modified by surfactant CrO3 by using dipping technique. The surface modified film suppresses the response to ammonia and enhances to H2S gas. The surface modification of films changes the adsorption-desorption relationship with the target gas and shifts its selectivity. The gas response, selectivity, response and recovery time of the pure and modified films were measured and presented.

Studies on Gas Sensing Performance of Cr-doped Indium Oxide Thick Film Sensors

Directory of Open Access Journals (Sweden)

D. N. Chavan

2011-02-01

Full Text Available A series of In1-xCrxO3 composites, with x ranging from 0.01 to 0.5wt% were prepared by mechanochemically starting from InCl3 and CrO3. Structural and micro structural characteristics of the sample were investigated by XRD, SEM with EDAX. Thick films of pure Indium Oxide and composites were prepared by standard screen printing technique. The gas sensitivity of these thick films was tested for various gases. The pure Indium Oxide thick film (x=0 shows maximum sensitivity to ethanol vapour (80 ppm at 350 oC, but composite-A (x=0.01 thick film shows maximum sensitivity to H2S gas (40 ppm at 250 oC, composite-B (x=0.1 thick film shows higher sensitivity to NH3 gas (80 ppm at 250 oC and composite-C (x=0.5 thick film shows maximum sensitivity to Cl2 gas (80 ppm at 350 oC. A systematic study of gas sensing performance of the sensors indicates the key role played by concentration variation of Cr doped species. The sensitivity, selectivity and recovery time of the sensor were measured and presented.

The evolution of magneto-transport and magneto-optical properties of thin La{sub 0.8}Ag{sub 0.1}MnO{sub 3+{delta}} films possessing the in-plane variant structure as a function of the film thickness

Energy Technology Data Exchange (ETDEWEB)

Melnikov, O V [Lomonosov Moscow State University, 119992 Moscow (Russian Federation); Sukhorukov, Yu P [Institute of Metal Physics, Ural Division of RAN, 620219 Ekaterinburg (Russian Federation); Telegin, A V [Institute of Metal Physics, Ural Division of RAN, 620219 Ekaterinburg (Russian Federation); Gan' shina, E A [Lomonosov Moscow State University, 119992 Moscow (Russian Federation); Loshkareva, N N [Institute of Metal Physics, Ural Division of RAN, 620219 Ekaterinburg (Russian Federation); Kaul, A R [Lomonosov Moscow State University, 119992 Moscow (Russian Federation); Gorbenko, O Yu [Lomonosov Moscow State University, 119992 Moscow (Russian Federation); Vinogradov, A N [Lomonosov Moscow State University, 119992 Moscow (Russian Federation); Smoljak, I B [Institute of Metal Physics, Ural Division of RAN, 620219 Ekaterinburg (Russian Federation)

2006-04-19

Epitaxial La{sub 0.8}Ag{sub 0.1}MnO{sub 3+{delta}} films of different thicknesses (500-1000 nm) were grown on ZrO{sub 2}(Y{sub 2}O{sub 3}) substrates. Their optical, magneto-optical and transport properties were studied in order to clarify the effect of the epitaxial variant structure and Ag ion distribution on the conductivity, magnetoresistance and infrared magnetotransmission in these films. An original method was developed for separating MR contributions related to the colossal magnetoresistance near T{sub C} and the tunnelling magnetoresistance. It was established that in the La{sub 0.8}Ag{sub 0.1}MnO{sub 3+{delta}} films spin-polarization of electrons P reached {approx}0.5. The transverse Kerr effect revealed the irregular distribution of Ag ions through the film thickness. The comparison of optical and electrical data implies lower silver content near the film-substrate boundary in relation to that in the domain volume.

Thickness-dependence of optical constants for Ta2O5 ultrathin films

International Nuclear Information System (INIS)

Zhang, Dong-Xu; Zheng, Yu-Xiang; Cai, Qing-Yuan; Lin, Wei; Wu, Kang-Ning; Mao, Peng-Hui; Zhang, Rong-Jun; Zhao, Hai-bin; Chen, Liang-Yao

2012-01-01

An effective method for determining the optical constants of Ta 2 O 5 thin films deposited on crystal silicon (c-Si) using spectroscopic ellipsometry (SE) measurement with a two-film model (ambient-oxide-interlayer-substrate) was presented. Ta 2 O 5 thin films with thickness range of 1-400 nm have been prepared by the electron beam evaporation (EBE) method. We find that the refractive indices of Ta 2 O 5 ultrathin films less than 40 nm drop with the decreasing thickness, while the other ones are close to those of bulk Ta 2 O 5 . This phenomenon was due to the existence of an interfacial oxide region and the surface roughness of the film, which was confirmed by the measurement of atomic force microscopy (AFM). Optical properties of ultrathin film varying with the thickness are useful for the design and manufacture of nano-scaled thin-film devices. (orig.)

Thickness-dependence of optical constants for Ta2O5 ultrathin films

Science.gov (United States)

Zhang, Dong-Xu; Zheng, Yu-Xiang; Cai, Qing-Yuan; Lin, Wei; Wu, Kang-Ning; Mao, Peng-Hui; Zhang, Rong-Jun; Zhao, Hai-bin; Chen, Liang-Yao

2012-09-01

An effective method for determining the optical constants of Ta2O5 thin films deposited on crystal silicon (c-Si) using spectroscopic ellipsometry (SE) measurement with a two-film model (ambient-oxide-interlayer-substrate) was presented. Ta2O5 thin films with thickness range of 1-400 nm have been prepared by the electron beam evaporation (EBE) method. We find that the refractive indices of Ta2O5 ultrathin films less than 40 nm drop with the decreasing thickness, while the other ones are close to those of bulk Ta2O5. This phenomenon was due to the existence of an interfacial oxide region and the surface roughness of the film, which was confirmed by the measurement of atomic force microscopy (AFM). Optical properties of ultrathin film varying with the thickness are useful for the design and manufacture of nano-scaled thin-film devices.

Ellipsometry study on Pd thin film grown by atomic layer deposition with Maxwell–Garnett effective medium approximation model

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yihang; Zhou, Xueqi; Cao, Kun [State Key Laboratory of Digital of Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Chen, Xiuguo; Deng, Zhang [State Key Laboratory of Digital of Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Liu, Shiyuan, E-mail: shyliu@hust.edu.cn [State Key Laboratory of Digital of Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Shan, Bin [State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Chen, Rong, E-mail: rongchen@mail.hust.edu.cn [State Key Laboratory of Digital of Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China)

2015-10-30

Maxwell–Garnett effective medium approximation (MG-EMA) model is chosen to study Pd ultrathin film grown on Si substrate, as well as its growth on self-assembled monolayers (SAMs) modified substrate respectively. The general oscillator (GO) model with one Drude and two Lorentz oscillators is firstly applied to fix the optical constants of Pd. Compared with Pd bulk model, MG-EMA model with GO is more reliable to predict the film thickness verified by X-ray reflection test. The stable growth rate on Si substrate reveals our methods are feasible and the quartz crystal microbalance measurement confirms the stability of the ALD chamber. For Pd coverage, MG-EMA fitting result is similar to the statistical computation from scanning electron microscope when Pd ALD cycles are over 400, while large bias exists for cycles under 400, might be due to that air is not the proper filling medium between nanoparticles. Then we change the filling medium into SAMs as a comparison, better fitting performance is obtained. It is demonstrated that the filling medium between nanoparticles is important for the application of MG-EMA model. - Highlights: • Ultrathin Pd thin films were grown by atomic layer deposition. • The measurement of thin film was important to understand initial growth behavior. • Maxwell–Garnett effective medium approximation model was applied. • Pd nanoparticle size and coverage were studied. • The filling medium between nanoparticles was important for model application.

Thin dielectric film thickness determination by advanced transmission electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Diebold, A.C.; Foran, B.; Kisielowski, C.; Muller, D.; Pennycook, S.; Principe, E.; Stemmer, S.

2003-09-01

High Resolution Transmission Electron Microscopy (HR-TEM) has been used as the ultimate method of thickness measurement for thin films. The appearance of phase contrast interference patterns in HR-TEM images has long been confused as the appearance of a crystal lattice by non-specialists. Relatively easy to interpret crystal lattice images are now directly observed with the introduction of annular dark field detectors for scanning TEM (STEM). With the recent development of reliable lattice image processing software that creates crystal structure images from phase contrast data, HR-TEM can also provide crystal lattice images. The resolution of both methods was steadily improved reaching now into the sub Angstrom region. Improvements in electron lens and image analysis software are increasing the spatial resolution of both methods. Optimum resolution for STEM requires that the probe beam be highly localized. In STEM, beam localization is enhanced by selection of the correct aperture. When STEM measurement is done using a highly localized probe beam, HR-TEM and STEM measurement of the thickness of silicon oxynitride films agree within experimental error. In this paper, the optimum conditions for HR-TEM and STEM measurement are discussed along with a method for repeatable film thickness determination. The impact of sample thickness is also discussed. The key result in this paper is the proposal of a reproducible method for film thickness determination.

Misfit strain-film thickness phase diagrams and related electromechanical properties of epitaxial ultra-thin lead zirconate titanate films

Energy Technology Data Exchange (ETDEWEB)

Qiu, Q.Y.; Mahjoub, R. [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Alpay, S.P. [Materials Science and Engineering Program and Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States); Nagarajan, V., E-mail: nagarajan@unsw.edu.au [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia)

2010-02-15

The phase stability of ultra-thin (0 0 1) oriented ferroelectric PbZr{sub 1-x}Ti{sub x}O{sub 3} (PZT) epitaxial thin films as a function of the film composition, film thickness, and the misfit strain is analyzed using a non-linear Landau-Ginzburg-Devonshire thermodynamic model taking into account the electrical and mechanical boundary conditions. The theoretical formalism incorporates the role of the depolarization field as well as the possibility of the relaxation of in-plane strains via the formation of microstructural features such as misfit dislocations at the growth temperature and ferroelastic polydomain patterns below the paraelectric-ferroelectric phase transformation temperature. Film thickness-misfit strain phase diagrams are developed for PZT films with four different compositions (x = 1, 0.9, 0.8 and 0.7) as a function of the film thickness. The results show that the so-called rotational r-phase appears in a very narrow range of misfit strain and thickness of the film. Furthermore, the in-plane and out-of-plane dielectric permittivities {epsilon}{sub 11} and {epsilon}{sub 33}, as well as the out-of-plane piezoelectric coefficients d{sub 33} for the PZT thin films, are computed as a function of misfit strain, taking into account substrate-induced clamping. The model reveals that previously predicted ultrahigh piezoelectric coefficients due to misfit-strain-induced phase transitions are practically achievable only in an extremely narrow range of film thickness, composition and misfit strain parameter space. We also show that the dielectric and piezoelectric properties of epitaxial ferroelectric films can be tailored through strain engineering and microstructural optimization.

Realistic reflectance spectrum of thin films covering a transparent optically thick substrate

Energy Technology Data Exchange (ETDEWEB)

Cesaria, M., E-mail: maura.cesaria@le.infn.it; Caricato, A. P.; Martino, M. [Department of Mathematics and Physics “Ennio De Giorgi,” University of Salento, Via Arnesano, I-73100 Lecce (Italy)

2014-07-21

A spectrophotometric strategy is presented and discussed for calculating realistically the reflectance spectrum of an absorbing film deposited over a thick transparent or semi-transparent substrate. The developed route exploits simple mathematics, has wide range of applicability (high-to-weak absorption regions and thick-to-ultrathin films), rules out numerical and curve-fitting procedures as well as model-functions, inherently accounts for the non-measurable contribution of the film-substrate interface as well as substrate backside, and describes the film reflectance spectrum as determined by the experimental situation (deposition approach and parameters). The reliability of the method is tested on films of a well-known material (indium tin oxide) by deliberately changing film thickness and structural quality through doping. Results are found consistent with usual information yielded by reflectance, its inherent relationship with scattering processes and contributions to the measured total reflectance.

Solvent annealing induced phase separation and dewetting in PMMA∕SAN blend film: film thickness and solvent dependence.

Science.gov (United States)

You, Jichun; Zhang, Shuangshuang; Huang, Gang; Shi, Tongfei; Li, Yongjin

2013-06-28

The competition between "dewetting" and "phase separation" behaviors in polymer blend films attracts significant attention in the last decade. The simultaneous phase separation and dewetting in PMMA∕SAN [poly(methyl methacrylate) and poly(styrene-ran-acrylonitrile)] blend ultrathin films upon solvent annealing have been observed for the first time in our previous work. In this work, film thickness and annealing solvent dependence of phase behaviors in this system has been investigated using atomic force microscopy and grazing incidence small-angle X-ray scattering (GISAXS). On one hand, both vertical phase separation and dewetting take place upon selective solvent vapor annealing, leading to the formation of droplet∕mimic-film structures with various sizes (depending on original film thickness). On the other hand, the whole blend film dewets the substrate and produces dispersed droplets on the silicon oxide upon common solvent annealing. GISAXS results demonstrate the phase separation in the big dewetted droplets resulted from the thicker film (39.8 nm). In contrast, no period structure is detected in small droplets from the thinner film (5.1 nm and 9.7 nm). This investigation indicates that dewetting and phase separation in PMMA∕SAN blend film upon solvent annealing depend crucially on the film thickness and the atmosphere during annealing.

Flexoelectricity induced increase of critical thickness in epitaxial ferroelectric thin films

International Nuclear Information System (INIS)

Zhou Hao; Hong Jiawang; Zhang Yihui; Li Faxin; Pei Yongmao; Fang Daining

2012-01-01

Flexoelectricity describes the coupling between polarization and strain/stress gradients in insulating crystals. In this paper, using the Landau-Ginsburg-Devonshire phenomenological approach, we found that flexoelectricity could increase the theoretical critical thickness in epitaxial BaTiO 3 thin films, below which the switchable spontaneous polarization vanishes. This increase is remarkable in tensile films while trivial in compressive films due to the electrostriction caused decrease of potential barrier, which can be easily destroyed by the flexoelectricity, between the ferroelectric state and the paraelectric state in tensile films. In addition, the films are still in a uni-polar state even below the critical thickness due to the flexoelectric effect.

Flexoelectricity induced increase of critical thickness in epitaxial ferroelectric thin films

Energy Technology Data Exchange (ETDEWEB)

Zhou Hao [State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871 (China); Hong Jiawang; Zhang Yihui [Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China); Li Faxin [State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871 (China); Pei Yongmao, E-mail: peiym@pku.edu.cn [State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871 (China); Fang Daining, E-mail: fangdn@pku.edu.cn [State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871 (China); Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China)

2012-09-01

Flexoelectricity describes the coupling between polarization and strain/stress gradients in insulating crystals. In this paper, using the Landau-Ginsburg-Devonshire phenomenological approach, we found that flexoelectricity could increase the theoretical critical thickness in epitaxial BaTiO{sub 3} thin films, below which the switchable spontaneous polarization vanishes. This increase is remarkable in tensile films while trivial in compressive films due to the electrostriction caused decrease of potential barrier, which can be easily destroyed by the flexoelectricity, between the ferroelectric state and the paraelectric state in tensile films. In addition, the films are still in a uni-polar state even below the critical thickness due to the flexoelectric effect.

Magnetic properties and microstructure investigation of electrodeposited FeNi/ITO films with different thickness

International Nuclear Information System (INIS)

Cao, Derang; Wang, Zhenkun; Feng, Erxi; Wei, Jinwu; Wang, Jianbo; Liu, Qingfang

2013-01-01

Highlights: •FeNi alloy thin films with different thickness deposited on Indium Tin Oxides (ITOs) conductive glass substrates by electrodeposition method. •A columnar crystalline microstructure and domain structure were obtained in FeNi thin films. •Particular FMR spectra of FeNi alloy with different thickness were studied. -- Abstract: FeNi alloy thin films with different thickness deposited on Indium Tin Oxides (ITOs) conductive glass substrates from the electrolytes by electrodeposition method have been studied by magnetic force microscopy (MFM), scanning electron microscopy (SEM) and ferromagnetic resonance (FMR) technique. For these films possessing an in-plane isotropy, the remanence decreases with the increasing of film thickness and the critical thickness that a stripe domain structure emerges is about 116 nm. Characteristic differences of the FMR spectra of different thickness are also observed. The results show that the resonance field at high measured angle increases firstly then decreases with increasing thickness, which may be related to the striped domain structure

Ethanol vapour sensing properties of screen printed WO 3 thick films

Indian Academy of Sciences (India)

The ethanol vapour sensing properties of these thick films were investigated at different operating temperatures and ethanol vapour concentrations. The WO3 thick films exhibit excellent ethanol vapour sensing properties with a maximum sensitivity of ∼1424.6% at 400°C in air atmosphere with fast response and recovery ...

Alignment of muscle precursor cells on the vertical edges of thick carbon nanotube films

Energy Technology Data Exchange (ETDEWEB)

Holt, Ian, E-mail: ian.holt@rjah.nhs.uk [Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry, Shropshire SY10 7AG (United Kingdom); Institute for Science and Technology in Medicine, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom); Gestmann, Ingo, E-mail: Ingo.Gestmann@fei.com [FEI Europe B.V., Achtseweg Noord 5, 5651 Eindhoven (Netherlands); Wright, Andrew C., E-mail: a.wright@glyndwr.ac.uk [Advanced Materials Research Laboratory, Glyndwr University, Plas Coch, Mold Rd, Wrexham LL11 2AW (United Kingdom)

2013-10-15

The development of scaffolds and templates is an essential aspect of tissue engineering. We show that thick (> 0.5 mm) vertically aligned carbon nanotube films, made by chemical vapour deposition, can be used as biocompatible substrates for the directional alignment of mouse muscle cells where the cells grow on the exposed sides of the films. Ultra high resolution scanning electron microscopy reveals that the films themselves consist mostly of small diameter (10 nm) multi-wall carbon nanotubes of wavy morphology with some single wall carbon nanotubes. Our findings show that for this alignment to occur the nanotubes must be in pristine condition. Mechanical wiping of the films to create directional alignment is detrimental to directional bioactivity. Larger areas for study have been formed from a composite of multiply stacked narrow strips of nanotubes wipe-transferred onto elastomer supports. These composite substrates appear to show a useful degree of alignment of the cells. Highlights: • Highly oriented muscle precursor cells grown on edges of carbon nanotube pads • Mechanical treatment of nanotube pads highly deleterious to cell growth on edges • Larger areas created from wipe-transfer of narrow strips of nanotubes onto elastomer supports • Very high resolution SEM reveals clues to aligned cell growth.

Alignment of muscle precursor cells on the vertical edges of thick carbon nanotube films

International Nuclear Information System (INIS)

Holt, Ian; Gestmann, Ingo; Wright, Andrew C.

2013-01-01

The development of scaffolds and templates is an essential aspect of tissue engineering. We show that thick (> 0.5 mm) vertically aligned carbon nanotube films, made by chemical vapour deposition, can be used as biocompatible substrates for the directional alignment of mouse muscle cells where the cells grow on the exposed sides of the films. Ultra high resolution scanning electron microscopy reveals that the films themselves consist mostly of small diameter (10 nm) multi-wall carbon nanotubes of wavy morphology with some single wall carbon nanotubes. Our findings show that for this alignment to occur the nanotubes must be in pristine condition. Mechanical wiping of the films to create directional alignment is detrimental to directional bioactivity. Larger areas for study have been formed from a composite of multiply stacked narrow strips of nanotubes wipe-transferred onto elastomer supports. These composite substrates appear to show a useful degree of alignment of the cells. Highlights: • Highly oriented muscle precursor cells grown on edges of carbon nanotube pads • Mechanical treatment of nanotube pads highly deleterious to cell growth on edges • Larger areas created from wipe-transfer of narrow strips of nanotubes onto elastomer supports • Very high resolution SEM reveals clues to aligned cell growth

Thickness-modulated tungsten-carbon superconducting nanostructures grown by focused ion beam induced deposition for vortex pinning up to high magnetic fields.

Science.gov (United States)

Serrano, Ismael García; Sesé, Javier; Guillamón, Isabel; Suderow, Hermann; Vieira, Sebastián; Ibarra, Manuel Ricardo; De Teresa, José María

2016-01-01

We report efficient vortex pinning in thickness-modulated tungsten-carbon-based (W-C) nanostructures grown by focused ion beam induced deposition (FIBID). By using FIBID, W-C superconducting films have been created with thickness modulation properties exhibiting periodicity from 60 to 140 nm, leading to a strong pinning potential for the vortex lattice. This produces local minima in the resistivity up to high magnetic fields (2.2 T) in a broad temperature range due to commensurability effects between the pinning potential and the vortex lattice. The results show that the combination of single-step FIBID fabrication of superconducting nanostructures with built-in artificial pinning landscapes and the small intrinsic random pinning potential of this material produces strong periodic pinning potentials, maximizing the opportunities for the investigation of fundamental aspects in vortex science under changing external stimuli (e.g., temperature, magnetic field, electrical current).

Towards a new thickness-independent gamma radiation plastic film dosimeter

International Nuclear Information System (INIS)

Vieira, Marli Barbosa; Araujo, Patricia L.; Araujo, Elma S.

2013-01-01

A 100% national single-use gamma radiation plastic film dosimeter is presented in this work. A new approach for the development of this material allowed a step forward in the performance of poly (methyl metacrylate) films (PMMA) colored with bromothymol blue (BTB) acid-base indicator. We manage to improve dosimeter performance by introducing a gamma radiation insensitive dye to compensate film thickness variations. By doing so, we were able to obtain consistent dose-response correlations within a set of samples presenting 46 to 110 micrometers in thickness. Hence, our PMMA/BTB-P film dosimeter is suitable to measure absorbed dose in the 2-100kGy range even when film thickness undergoes more than 100% of variation. In addition, dose response data remain practically unaltered for four months after the exposure, when dosimeter films are kept in dark conditions and under refrigeration. The radiation effects on the optical properties were evaluated for Ultraviolet-Visible (UV-Vis) spectrophotometric analysis. Data of characteristic dose-response correlation in terms of changes in the maximum UV-Vis absorption due to radiation, and stability in time are also described. This potential new product is a promising tool for industrial radiation facilities, especially in gamma sterilization of medical supplies. (author)

Ellipsometric investigation of nitrogen doped diamond thin films grown in microwave CH{sub 4}/H{sub 2}/N{sub 2} plasma enhanced chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Ficek, Mateusz, E-mail: rbogdan@eti.pg.gda.pl [Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology, 11/12 G. Narutowicza St., 80-233 Gdansk (Poland); Institute for Materials Research (IMO), Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); Sankaran, Kamatchi J.; Haenen, Ken [Institute for Materials Research (IMO), Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); Ryl, Jacek; Darowicki, Kazimierz [Department of Electrochemistry, Corrosion and Material Engineering, Gdansk University of Technology, 11/12 Narutowicza St., 80-233 Gdansk (Poland); Bogdanowicz, Robert [Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology, 11/12 G. Narutowicza St., 80-233 Gdansk (Poland); Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125 (United States); Lin, I-Nan [Department of Physics, Tamkang University, Tamsui 251, Taiwan (China)

2016-06-13

The influence of N{sub 2} concentration (1%–8%) in CH{sub 4}/H{sub 2}/N{sub 2} plasma on structure and optical properties of nitrogen doped diamond (NDD) films was investigated. Thickness, roughness, and optical properties of the NDD films in the VIS–NIR range were investigated on the silicon substrates using spectroscopic ellipsometry. The samples exhibited relatively high refractive index (2.6 ± 0.25 at 550 nm) and extinction coefficient (0.05 ± 0.02 at 550 nm) with a transmittance of 60%. The optical investigation was supported by the molecular and atomic data delivered by Raman studies, bright field transmission electron microscopy imaging, and X-ray photoelectron spectroscopy diagnostics. Those results revealed that while the films grown in CH{sub 4}/H{sub 2} plasma contained micron-sized diamond grains, the films grown using CH{sub 4}/H{sub 2}/(4%)N{sub 2} plasma exhibited ultranano-sized diamond grains along with n-diamond and i-carbon clusters, which were surrounded by amorphous carbon grain boundaries.

Electro-physical properties of superconducting ceramic thick film prepared by partial melting method.

Science.gov (United States)

Lee, Sang Heon

2013-05-01

BiSrCaCuO superconductor thick films were prepared at several curing temperatures, and their electro-physical properties were determined to find an optimum fabrication conditions. Critical temperatures of the superconductors were decreased with increasing melting temperature, which was related to the amount of equilibrium phases of the superconducting materials with temperature. The critical temperature of BiSrCaCuO bulk and thick film superconductors were 107 K and 96 K, respectively. The variation of susceptibility of the superconductor thick film formed at 950 degrees C had multi-step-type curve for 70 G externally applied field, whereas, a superconductor thick film formed at 885 degrees C had a single step-type curve like a bulk BiSrCaCuO ceramic superconductor in the temperature-susceptibility curves. A partial melting at 865 degrees C is one of optimum conditions for making a superconductor thick film with a relatively homogeneous phase.

Formation and physical properties of YBCO thick films grown by using the electrophoretic deposition method

CERN Document Server

Kim, U J; Kim, Y C; Han, S K; Kang, K Y

1999-01-01

Thick films of the YBa sub 2 Cu sub 3 O subgamma sub - subdelta (YBCO) superconductor were prepared by using the electrophoretic deposition technique and a flexible wire as the substrate. The transition temperature of the wires was 91 K, the intragranular magnetic critical current density J sub c sub g sup m sup a sup g was about 10 sup 5 A/cm sup 2 at 77 K in a weak field, and the transport J sub c sup t sup r sup a sup n sup s was about 365 A/cm sup 2 at 77 K. We calculated the intergranular magnetic critical current J sub c sub J sup m sup a sup g and the activation energy from the AC-susceptibility measurements, and their values were about 444 A/cm sup 2 at 77 K and 2.02 eV, respectively.

Thickness control in electrophoretic deposition of WO3 nanofiber thin films for solar water splitting

International Nuclear Information System (INIS)

Fang, Yuanxing; Lee, Wei Cheat; Canciani, Giacomo E.; Draper, Thomas C.; Al-Bawi, Zainab F.; Bedi, Jasbir S.; Perry, Christopher C.; Chen, Qiao

2015-01-01

Graphical abstract: - Highlights: • A novel method combining electrospinning and electrophoretic deposition was established for the creation of nanostructured semiconductor thin films. • The created thin films displayed a high chemical stability with a controllable thickness. • The PEC water splitting performance of the thin films was optimized by fine-tuning the thickness of the films. • A maximum photoconversion efficiency was achieved by 18 μm nanofibrous thin films. - Abstract: Electrophoretic deposition (EPD) of ground electrospun WO 3 nanofibers was applied to create photoanodes with controlled morphology for the application of photoelectrochemical (PEC) water splitting. The correlations between deposition parameters and film thicknesses were investigated with theoretical models to precisely control the morphology of the nanostructured porous thin film. The photoconversion efficiency was further optimized as a function of film thickness. A maximum photoconversion efficiency of 0.924% from electrospun WO 3 nanofibers that EPD deposited on a substrate was achieved at a film thickness of 18 μm.

High-performance piezoelectric thick film based energy harvesting micro-generators for MEMS

DEFF Research Database (Denmark)

Zawada, Tomasz; Hansen, Karsten; Lou-Moeller, Rasmus

2010-01-01

and are transformed by the energy harvesting micro-generator into usable electrical signal. The micro-generator comprises a silicon cantilever with integrated InSensor® TF2100 PZT thick film deposited using screen-printing. The output power versus frequency and electrical load has been investigated. Furthermore......, devices based on modified, pressure treated thick film materials have been tested and compared with the commercial InSensor® TF2100 PZT thick films. It has been found that the structures based on the pressure treated materials exhibit superior properties in terms of energy output....

Alkaline-doped manganese perovskite thin films grown by MOCVD

International Nuclear Information System (INIS)

Bibes, M.; Gorbenko, O.; Martinez, B.; Kaul, A.; Fontcuberta, J.

2000-01-01

We report on the preparation and characterization of La 1-x Na x MnO 3 thin films grown by MOCVD on various single-crystalline substrates. Under appropriate conditions epitaxial thin films have been obtained. The Curie temperatures of the films, which are very similar to those of bulk samples of similar composition, reflect the residual strain caused by the substrate. The anisotropic magnetoresistance AMR of the films has been analyzed in some detail, and it has been found that it has a two-fold symmetry at any temperature. Its temperature dependence mimics that of the electrical resistivity and magnetoresistance measured at similar fields, thus suggesting that the real structure of the material contributes to the measured AMR besides the intrinsic component

Epitaxial Oxide Thin Films Grown by Solid Source Metal-Organic Chemical Vapor Deposition.

Science.gov (United States)

Lu, Zihong

1995-01-01

The conventional liquid source metal-organic chemical vapor deposition (MOCVD) technique is capable of producing large area, high quality, single crystal semiconductor films. However, the growth of complex oxide films by this method has been hampered by a lack of suitable source materials. While chemists have been actively searching for new source materials, the research work reported here has demonstrated the successful application of solid metal-organic sources (based on tetramethylheptanedionate) to the growth of high quality thin films of binary compound cerium dioxide (CeO_2), and two more complex materials, the ternary compound lithium niobate (LiNbO_3), with two cations, and the quaternary compound strontium barium niobate (SBN), with three cations. The growth of CeO_2 thin films on (1012)Al_2O_3 substrates has been used as a model to study the general growth behavior of oxides. Factors affecting deposition rate, surface morphology, out-of-plane mosaic structure, and film orientation have been carefully investigated. A kinetic model based on gas phase prereaction is proposed to account for the substrate temperature dependence of film orientation found in this system. Atomically smooth, single crystal quality cerium dioxide thin films have been obtained. Superconducting YBCO films sputtered on top of solid source MOCVD grown thin cerium dioxide buffer layers on sapphire have been shown to have physical properties as good as those of YBCO films grown on single crystal MgO substrates. The thin film growth of LiNbO_3 and Sr_{1-x}Ba _{x}Nb_2 O_6 (SBN) was more complex and challenging. Phase purity, transparency, in-plane orientation, and the ferroelectric polarity of LiNbO _3 films grown on sapphire substrates was investigated. The first optical quality, MOCVD grown LiNbO _3 films, having waveguiding losses of less than 2 dB/cm, were prepared. An important aspect of the SBN film growth studies involved finding a suitable single crystal substrate material. Mg

Study of lead free ferroelectrics using overlay technique on thick film microstrip ring resonator

Directory of Open Access Journals (Sweden)

Shridhar N. Mathad

2016-03-01

Full Text Available The lead free ferroelectrics, strontium barium niobates, were synthesized via the low cost solid state reaction method and their fritless thick films were fabricated by screen printing technique on alumina substrate. The X band response (complex permittivity at very high frequencies of Ag thick film microstrip ring resonator perturbed with strontium barium niobates (SrxBa1-xNb2O6 in form of bulk and thick film was measured. A new approach for determination of complex permittivity (ε′ and ε′′ in the frequency range 8–12 GHz, using perturbation of Ag thick film microstrip ring resonator (MSRR, was applied for both bulk and thick film of strontium barium niobates (SrxBa1-xNb2O6. The microwave conductivity of the bulk and thick film lie in the range from 1.779 S/cm to 2.874 S/cm and 1.364 S/cm to 2.296 S/cm, respectively. The penetration depth of microwave in strontium barium niobates is also reported.

Studies on Gas Sensing Performance of Pure and Surface Chrominated Indium Oxide Thick Film Resistors

Directory of Open Access Journals (Sweden)

D. N. CHAVAN

2010-12-01

Full Text Available The thick films of AR grade In2O3 were prepared by standard screen-printing technique. The gas sensing performance of thick film was tested for various gases. It showed maximum gas response to ethanol vapor at 350 oC for 80 ppm. To improve the gas response and selectivity of the film towards a particular gas, In2O3 thick films were modified by dipping them in an aqueous solution of 0.1 M CrO3 for different intervals of time. The surface chrominated (20 min In2O3 thick film showed maximum response to H2S gas (40 ppm than pure In2O3 thick film at 250 oC. Chromium oxide on the surface of the film shifts the gas response from ethanol vapor to H2S gas. A systematic study of sensing performance of the sensor indicates the key role played by chromium oxide on the surface of thick film. The selectivity, gas response and recovery time of the sensor were measured and presented.

High Ic, YBa2Cu3O7-x films grown at very high rates by liquid assisted growth incorporating lightly Au-doped SrTiO3 buffers

International Nuclear Information System (INIS)

Kursumovic, A; Durrell, J H; Harrington, S; Wimbush, S; MacManus-Driscoll, J L; Maiorov, B; Zhou, H; Stan, L; Holesinger, T G; Wang, H

2009-01-01

YBa 2 Cu 3 O 7-x (YBCO) thick films were grown by hybrid liquid phase epitaxy (HLPE) on (001) SrTiO 3 (STO) substrates. In the presence of a 100 nm thick, 5 mol% Au-doped STO buffer, self-field critical current densities, J c sf , at 77 K of ∼2.4 MA cm -2 and critical currents, I c sf , up to 700 A (cm-width) -1 were achieved. The J c value is virtually independent of thickness and the growth rates are very high (∼1 μm min -1 ). From transmission electron microscopy (TEM), Y 2 O 3 nanocloud extended defects (∼100 nm in size) were identified as the pinning defects in the films. Enhanced random pinning was induced by the presence of Au in the buffer.

Size effects of polycrystalline lanthanum modified Bi4Ti3O12 thin films

International Nuclear Information System (INIS)

Simoes, A.Z.; Riccardi, C.S.; Cavalcante, L.S.; Gonzalez, A.H.M.; Longo, E.; Varela, J.A.

2008-01-01

The film thickness dependence on the ferroelectric properties of lanthanum modified bismuth titanate Bi 3.25 La 0.75 Ti 3 O 12 was investigated. Films with thicknesses ranging from 230 to 404 nm were grown on platinum-coated silicon substrates by the polymeric precursor method. The internal strain is strongly influenced by the film thickness. The morphology of the film changes as the number of layers increases indicating a thickness dependent grain size. The leakage current, remanent polarization and drive voltage were also affected by the film thickness

Attempt to produce both thick and thinned flowing superfluid films

International Nuclear Information System (INIS)

Kwoh, D.S.W.; Goodstein, D.L.

1977-01-01

As discussed in the preceding paper by Graham, a controversy has arisen over conflicting reports of whether a superfluid film becomes thinned when it is set into motion. We have performed an experiment designed to reproduce as nearly as possible two previous measurements giving opposite results. Our experiment is also designed to test directly a theory proposed by Goodstein and Saffman which would have reconciled the apparently contradictory observations. We are unable to reproduce the thick-film result, finding kinetic thinning in all cases, even where the Goodstein--Saffman theory would lead us to expect a thick film. We conclude, in agreement with Graham, that the film is always thinned when it flows, and that the theory is therefore unnecessary

Laser Cutting of Thick Diamond Films Using Low-Power Laser

Energy Technology Data Exchange (ETDEWEB)

Park, Y.J.; Baik, Y.J. [Korea Institute of Science and Technology, Seoul (Korea)

2000-02-01

Laser cutting of thick diamond films is studied rising a low-power(10 W) copper vapor laser. Due to the existence of the saturation depth in laser cutting, thick diamond films are not easily cut by low-power lasers. In this study, we have adopted a low thermal- conductivity underlayer of alumina and a heating stage (up to 500 deg. C in air) to prevent the laser energy from consuming-out and, in turn, enhance the cutting efficiency. Aspect ratio increases twice from 3.5 to 7 when the alumina underlayer used. Adopting a heating stage also increases aspect ratio and more than 10 is obtained at higher temperatures than 400 deg. C. These results show that thick diamond films can be cut, with low-power lasers, simply by modifying the thermal property of underlayer. (author). 13 refs., 5 figs.

Thickness-modulated anisotropic ferromagnetism in Fe-doped epitaxial HfO2 thin films

Science.gov (United States)

Liu, Wenlong; Liu, Ming; Zhang, Ruyi; Ma, Rong; Wang, Hong

2017-10-01

Epitaxial tetragonal Fe-doped Hf0.95Fe0.05O2 (FHO) thin films with various thicknesses were deposited on (001)-oriented NdCaAlO4 (NCAO) substrates by using a pulsed laser deposition (PLD) system. The crystal structure and epitaxial nature of the FHO thin films were confirmed by typical x-ray diffraction (XRD) θ-2θ scan and reciprocal space mapping (RSM). The results indicate that two sets of lattice sites exist with two different crystal orientations [(001) and (100)] in the thicker FHO thin films. Further, the intensity of the (100) direction increases with the increase in thicknesses, which should have a significant effect on the anisotropic magnetization of the FHO thin films. Meanwhile, all the FHO thin films possess a tetragonal phase structure. An anisotropy behavior in magnetization has been observed in the FHO thin films. The anisotropic magnetization of the FHO thin films is slowly weakened as the thickness increases. Meanwhile, the saturation magnetization (Ms) of both in-plane and out-of-plane decreases with the increase in the thickness. The change in the anisotropic magnetization and Ms is attributed to the crystal lattice and the variation in the valence of Fe ions. These results indicate that the thickness-modulated anisotropic ferromagnetism of the tetragonal FHO epitaxial thin films is of potential use for the integration of metal-oxide semiconductors with spintronics.

Surface functionalization by fine ultraviolet-patterning of nanometer-thick liquid lubricant films

International Nuclear Information System (INIS)

Lu, Renguo; Zhang, Hedong; Komada, Suguru; Mitsuya, Yasunaga; Fukuzawa, Kenji; Itoh, Shintaro

2014-01-01

Highlights: • We present fine UV-patterning of nm-thick liquid films for surface functionalization. • The patterned films exhibit both a morphological pattern and a functional pattern of different surface properties. • The finest pattern linewidth was 0.5 μm. • Fine patterning is crucial for improving surface and tribological properties. - Abstract: For micro/nanoscale devices, surface functionalization is essential to achieve function and performance superior to those that originate from the inherent bulk material properties. As a method of surface functionalization, we dip-coated nanometer-thick liquid lubricant films onto solid surfaces and then patterned the lubricant films with ultraviolet (UV) irradiation through a photomask. Surface topography, adhesion, and friction measurements demonstrated that the patterned films feature a concave–convex thickness distribution with thicker lubricant in the irradiated regions and a functional distribution with lower adhesion and friction in the irradiated convex regions. The pattern linewidth ranged from 100 to as fine as 0.5 μm. The surface functionalization effect of UV-patterning was investigated by measuring the water contact angles, surface energies, friction forces, and depletion of the patterned, as-dipped, and full UV-irradiated lubricant films. The full UV-irradiated lubricant film was hydrophobic with a water contact angle of 102.1°, and had lower surface energy, friction, and depletion than the as-dipped film, which was hydrophilic with a water contact angle of 80.7°. This demonstrates that UV irradiation substantially improves the surface and tribological properties of the nanometer-thick liquid lubricant films. The UV-patterned lubricant films exhibited superior surface and tribological properties than the as-dipped film. The water contact angle increased and the surface energy, friction, and depletion decreased as the pattern linewidth decreased. In particular, the 0.5-μm patterned lubricant

Effect of Temperature on Film Thickness of Two Types of Commonly used Luting Cements.

Science.gov (United States)

Kumar, M Praveen; Priyadarshini, Reddy; Kumar, Yasangi M; Priya, K Shanthi; Chunchuvyshnavi, Chunchuvyshnavi; Yerrapragada, Harika

2017-12-01

The aim of this study is to evaluate the effect of temperature change on film thickness of both types of cements. Totally, 60 samples were prepared with 10 in each subgroup, thus comprising 30 in each group. Materials tested were glass ionomer cement (GIC) type I and zinc phosphate type I. Samples were manipulated with manufacturer's instructions and tested according to American Dental Association (ADA) guidelines. The mean values of film thickness were recorded for both groups I and II. In intragroup comparison of group 1, subgroup III (26.560 ± 0.489 urn) was found to have the highest film thickness followed by subgroup II (24.182 ± 0.576 urn) and the lowest in subgroup I (20.209 ± 0.493 urn). In intragroup comparison of group II, the film thickness recorded in subgroup III (25.215 ± 0.661 urn) was the highest followed by subgroup II (21.471 ± 0.771 urn) and the least in subgroup I (17.951 ± 0.654 urn; p film thickness than group I (23.650 ± 0.271). The results were found to be statistically significant (p film thickness. Zinc phosphate has less film thickness than GIC. Zinc phosphate should be preferred over GIC in clinical practice, and more stress should be given in mechanical preparation of crowns for better retentive quality of prosthesis.

Effect of thickness on electrical properties of SILAR deposited SnS thin films

Science.gov (United States)

Akaltun, Yunus; Astam, Aykut; Cerhan, Asena; ćayir, Tuba

2016-03-01

Tin sulfide (SnS) thin films of different thickness were prepared on glass substrates by successive ionic layer adsorption and reaction (SILAR) method at room temperature using tin (II) chloride and sodium sulfide aqueous solutions. The thicknesses of the films were determined using spectroscopic ellipsometry measurements and found to be 47.2, 65.8, 111.0, and 128.7nm for 20, 25, 30 and 35 deposition cycles respectively. The electrical properties of the films were investigated using d.c. two-point probe method at room temperature and the results showed that the resistivity was found to decrease with increasing film thickness.

The application of the barrier-type anodic oxidation method to thickness testing of aluminum films

Science.gov (United States)

Chen, Jianwen; Yao, Manwen; Xiao, Ruihua; Yang, Pengfei; Hu, Baofu; Yao, Xi

2014-09-01

The thickness of the active metal oxide film formed from a barrier-type anodizing process is directly proportional to its formation voltage. The thickness of the consumed portion of the metal film is also corresponding to the formation voltage. This principle can be applied to the thickness test of the metal films. If the metal film is growing on a dielectric substrate, when the metal film is exhausted in an anodizing process, because of the high electrical resistance of the formed oxide film, a sudden increase of the recorded voltage during the anodizing process would occur. Then, the thickness of the metal film can be determined from this voltage. As an example, aluminum films are tested and discussed in this work. This method is quite simple and is easy to perform with high precision.

Fourfold magnetic anisotropy, coercivity and magnetization reversal of Co/V bilayers grown on MgO(0 0 1)

Energy Technology Data Exchange (ETDEWEB)

Calleja, J F [Departamento de Fisica, Facultad de Ciencias, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain); Muro, M GarcIa del [Departament de Fisica Fonamental and Institut de Nanociencia i Nanotecnologia IN2UB de la Universitat de Barcelona, MartIi Franques, 1, E-08028 Barcelona (Spain); Presa, B [Departamento de Fisica, Facultad de Ciencias, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain); Matarranz, R [Departamento de Fisica, Facultad de Ciencias, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain); Corrales, J A [Departmento de Informatica, Universidad de Oviedo, Edificio Departamental 1, Campus de Viesques s/n, 33204 Gijon (Spain); Labarta, A [Departament de Fisica Fonamental and Institut de Nanociencia i Nanotecnologia IN2UB de la Universitat de Barcelona, MartIi Franques, 1, E-08028 Barcelona (Spain); Contreras, M C [Departamento de Fisica, Facultad de Ciencias, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain)

2007-11-21

Magnetic anisotropy and magnetization reversal of Al/Co/V/MgO(0 0 1) thin films have been investigated. The films were fabricated by magnetron sputtering. The roles of both Co and V layers thicknesses have been studied. Magnetic characterization has been carried out by transverse susceptibility (TS) measurements and hysteresis loops. Cobalt is grown in the hcp structure on V with the c axis parallel to the film plane. Two types of hcp Co crystal are grown with the c axes perpendicular to each other. This structure gives rise to a fourfold magnetic anisotropy. When the V layer thickness is below 40 A a superimposed uniaxial anisotropy develops, the effect of which is a depression in the TS, in agreement with theoretical calculations. This uniaxial anisotropy is induced by the substrate and due to a discontinuous growth of the V layer. For hcp Co grown on V, the magnetic anisotropy rapidly increases with Co layer thickness. In this case, unexpected shifted hysteresis loops along the hard axes were observed when the films were not saturated. This has been explained by taking into account the magnetization reversal along the hard axis: it proceeds via magnetization rotation of some portions of the film at high fields, and by domain wall motion of the rest of the film at lower field values.

Fourfold magnetic anisotropy, coercivity and magnetization reversal of Co/V bilayers grown on MgO(0 0 1)

International Nuclear Information System (INIS)

Calleja, J F; Muro, M GarcIa del; Presa, B; Matarranz, R; Corrales, J A; Labarta, A; Contreras, M C

2007-01-01

Magnetic anisotropy and magnetization reversal of Al/Co/V/MgO(0 0 1) thin films have been investigated. The films were fabricated by magnetron sputtering. The roles of both Co and V layers thicknesses have been studied. Magnetic characterization has been carried out by transverse susceptibility (TS) measurements and hysteresis loops. Cobalt is grown in the hcp structure on V with the c axis parallel to the film plane. Two types of hcp Co crystal are grown with the c axes perpendicular to each other. This structure gives rise to a fourfold magnetic anisotropy. When the V layer thickness is below 40 A a superimposed uniaxial anisotropy develops, the effect of which is a depression in the TS, in agreement with theoretical calculations. This uniaxial anisotropy is induced by the substrate and due to a discontinuous growth of the V layer. For hcp Co grown on V, the magnetic anisotropy rapidly increases with Co layer thickness. In this case, unexpected shifted hysteresis loops along the hard axes were observed when the films were not saturated. This has been explained by taking into account the magnetization reversal along the hard axis: it proceeds via magnetization rotation of some portions of the film at high fields, and by domain wall motion of the rest of the film at lower field values

Epitaxial single-crystal thin films of MnxTi1-xO2-δ grown on (rutile)TiO2 substrates with pulsed laser deposition: Experiment and theory

Energy Technology Data Exchange (ETDEWEB)

Ilton, Eugene S.; Droubay, Timothy C.; Chaka, Anne M.; Kovarik, Libor; Varga, Tamas; Arey, Bruce W.; Kerisit, Sebastien N.

2015-02-01

Epitaxial rutile-structured single-crystal MnxTi1-xO2-δ films were synthesized on rutile- (110) and -(001) substrates using pulsed laser deposition. The films were characterized by reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and aberration-corrected transmission electron microscopy (ACTEM). Under the present conditions, 400oC and PO2 = 20 mTorr, single crystal epitaxial thin films were grown for x = 0.13, where x is the nominal average mole fraction of Mn. In fact, arbitrarily thick films could be grown with near invariant Mn/Ti concentration profiles from the substrate/film interface to the film surface. In contrast, at x = 0.25, Mn became enriched towards the surface and a secondary nano-scale phase formed which appeared to maintain the basic rutile structure but with enhanced z-contrast in the tunnels, or tetrahedral interstitial sites. Ab initio thermodynamic calculations provided quantitative estimates for the destabilizing effect of expanding the β-MnO2 lattice parameters to those of TiO2-rutile, the stabilizing effect of diluting Mn with increasing Ti concentration, and competing reaction pathways.

Highly textured Sr, Nb co-doped BiFeO3 thin films grown on SrRuO3/Si substrates by rf- sputtering

International Nuclear Information System (INIS)

Ostos, C.; Raymond, O.; Siqueiros, J. M.; Suarez-Almodovar, N.; Bueno-Baques, D.; Mestres, L.

2011-01-01

In this study, (011)-highly oriented Sr, Nb co-doped BiFeO 3 (BFO) thin films were successfully grown on SrRuO 3 /Si substrates by rf-magnetron sputtering. The presence of parasite magnetic phases was ruled out based on the high resolution x-ray diffraction data. BFO films exhibited a columnar-like grain growth with rms surface roughness values of ≅5.3 nm and average grain sizes of ≅65-70 nm for samples with different thicknesses. Remanent polarization values (2P r ) of 54 μC cm -2 at room temperature were found for the BFO films with a ferroelectric behavior characteristic of an asymmetric device structure. Analysis of the leakage mechanisms for this structure in negative bias suggests Schottky injection and a dominant Poole-Frenkel trap-limited conduction at room temperature. Oxygen vacancies and Fe 3+ /Fe 2+ trap centers are consistent with the surface chemical bonding states analysis from x-ray photoelectron spectroscopy data. The (011)-BFO/SrRuO 3 /Si film structure exhibits a strong magnetic interaction at the interface between the multiferroic film and the substrate layer where an enhanced ferromagnetic response at 5 K was observed. Zero-field cooled (ZFC) and field cooled (FC) magnetization curves of this film system revealed a possible spin glass behavior at spin freezing temperatures below 30 K depending on the BFO film thickness.

Thick film heater for sensor application

International Nuclear Information System (INIS)

Milewski, J; Borecki, M; Kalenik, J; Król, K

2014-01-01

A thick film microheater was elaborated. The microheater is intended for fast heating of small volume samples under measurement in optical based system. Thermal analysis of microheater was carried out using finite element method (FEM) for heat transfer calculation as a function of time and space. A nodal heat transfer function was calculated in classical form including all basics mechanisms of heat exchange – heat conduction, convection and radiation were considered. Work focuses on the influence of some construction parameters (ex. length, thermal conductivity of substrate, substrate thickness) on microheater performance. The results show that application of thin substrate of low thermal conductivity and low thickness for miroheater construction and resistor of optimum dimensions leads to significant power consumption decrease and increase of overall optical measurement system performance.

Screen printed nanosized ZnO thick film

Indian Academy of Sciences (India)

Unknown

The ex- tracted powder was screen printed on glass substrates using ethyl cellulose as binder and turpinol as solvent. ... racterized and a thick film paste is prepared by adding suitable .... UV peak and a broad green emission which is usually.

Multifunctional thick-film structures based on spinel ceramics for environment sensors

International Nuclear Information System (INIS)

Vakiv, M; Hadzaman, I; Klym, H; Shpotyuk, O; Brunner, M

2011-01-01

Temperature sensitive thick films based on spinel-type NiMn 2 O 4 -CuMn 2 O 4 -MnCo 2 O 4 manganites with p- and p + -types of electrical conductivity and their multilayer p + -p structures were studied. These thick-film elements possess good electrophysical characteristics before and after long-term ageing test at 170 deg. C. It is shown that degradation processes connected with diffusion of metallic Ag into film grain boundaries occur in one-layer p-and p + -conductive films. Some part of the p + -p structures were of high stability, the relative electrical drift being no more than 1 %.

Ultra-large current transport in thick SmBa{sub 2}Cu{sub 3}O{sub 7−x} films grown by reactive co-evaporation

Energy Technology Data Exchange (ETDEWEB)

Kim, G.; Jin, H.J. [Department of Physics, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Jo, W., E-mail: wmjo@ewha.ac.kr [Department of Physics, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Nam, D.H.; Cheong, H. [Department of Physics, Sogang University, Seoul 121-742 (Korea, Republic of); Kim, H.S.; Oh, S.S.; Ko, R.K.; Jo, Y.S.; Ha, D.W. [The Korea Electrotechnology Research Institute (KERI), Changwon 641-120 (Korea, Republic of)

2015-06-15

Highlights: • Transport properties of 5 μm thick SmBa{sub 2}Cu{sub 3}O{sub 7−x} thin films were investigated. • Laser scanning microscopy was used to demonstrate local transport properties. • Temperature variable laser scanning microscopy shows correlation between structural and transport properties. • Optical measurements described nature of current transport properties in the coated conductors. - Abstract: Structural and transport properties of high performance SmBa{sub 2}Cu{sub 3}O{sub 7−x} coated conductors produced by a dual-chamber co-evaporation are presented. The 5 μm-thick SmBCO coated conductors grown on IBAD-MgO based Hastelloy metal templates show critical currents larger than 1020–1560 A/cm at 77 K and self-field. The current transport characteristics of the conductors are investigated by room-temperature thermoelectric microscopy and low-temperature bolometric microscopy. The local thermoelectric images show the tilted grains, grain boundaries, and microstructural defects on the surface of the coated conductors. The bias current-dependent bolometric response at low temperature displays the current of the local flux flow dissipation as an increasing bias. Furthermore, we measured micro-Raman scattering microscopic imaging on oxygen-related peaks of the conductors. Comparing the Raman signal images with the low temperature optical scanning maps, it is remarkable that the structural disorders represented by oxygen-related Raman peaks are closely related to the low temperature bolometric abnormalities. From this result, a nature of the dissipative current distribution in coated conductors is revealed. The scanning optical microscopic study will provide a promising method for quality assurance of coated conductors.

A wrinkling-based method for investigating glassy polymer film relaxation as a function of film thickness and temperature.

Science.gov (United States)

Chung, Jun Young; Douglas, Jack F; Stafford, Christopher M

2017-10-21

We investigate the relaxation dynamics of thin polymer films at temperatures below the bulk glass transition T g by first compressing polystyrene films supported on a polydimethylsiloxane substrate to create wrinkling patterns and then observing the slow relaxation of the wrinkled films back to their final equilibrium flat state by small angle light scattering. As with recent relaxation measurements on thin glassy films reported by Fakhraai and co-workers, we find the relaxation time of our wrinkled films to be strongly dependent on film thickness below an onset thickness on the order of 100 nm. By varying the temperature between room temperature and T g (≈100 °C), we find that the relaxation time follows an Arrhenius-type temperature dependence to a good approximation at all film thicknesses investigated, where both the activation energy and the relaxation time pre-factor depend appreciably on film thickness. The wrinkling relaxation curves tend to cross at a common temperature somewhat below T g , indicating an entropy-enthalpy compensation relation between the activation free energy parameters. This compensation effect has also been observed recently in simulated supported polymer films in the high temperature Arrhenius relaxation regime rather than the glassy state. In addition, we find that the film stress relaxation function, as well as the height of the wrinkle ridges, follows a stretched exponential time dependence and the short-time effective Young's modulus derived from our modeling decreases sigmoidally with increasing temperature-both characteristic features of glassy materials. The relatively facile nature of the wrinkling-based measurements in comparison to other film relaxation measurements makes our method attractive for practical materials development, as well as fundamental studies of glass formation.

Structure and electronic properties of Zn-tetra-phenyl-porphyrin single- and multi-layers films grown on Fe(001)-p(1 × 1)O

Energy Technology Data Exchange (ETDEWEB)

Bussetti, Gianlorenzo, E-mail: gianlorenzo.bussetti@polimi.it; Calloni, Alberto; Celeri, Matteo; Yivlialin, Rossella; Finazzi, Marco; Bottegoni, Federico; Duò, Lamberto; Ciccacci, Franco

2016-12-30

Highlights: • ZnTPP/Fe(001)-p(1 × 1)O is a prototypical system to investigate the porphyrin/thin metal oxide film interaction. • Oxygen layer plays a crucial role in decreasing the porphyrin-substrate interaction. • An ordered ZnTPP (5 × 5) reconstruction is found on the nominal 1 ML-thick film. • On Fe(001)-p(1 × 1)O the electronic properties of the ZnTPP film are preserved with respect to other substrates. - Abstract: The structure and the electronic properties of thin (1 molecular layer) and thick (20 molecular layers) Zn-tetra-phenyl-porphyrin (ZnTPP) films grown on a single metal oxide (MO) layer, namely Fe(001)-p(1 × 1)O, are shown and discussed. During the first stages of deposition, the ultra-thin MO layer reduces the molecule-substrate interaction enhancing the molecular diffusivity with the respect to other investigated substrates [namely, Si(111), Au(001) and oxygen-free Fe(001)]. On Fe(001)-p(1 × 1)O, ZnTPP molecules form an ordered and stable square-lattice array. The photoemission analysis of the valence bands reveals that all the characteristic features of the molecule are already visible in the 1 monolayer-thick sample spectrum. Similarly, the core level investigation suggests a weak molecule perturbation. The ZnTPP/Fe(001)-p(1 × 1)O interface represents a prototypical system to investigate the organic film adhesion on ultra-thin MO layers and the processes involved during the film growth.

Residual stress analysis in thick uranium films

International Nuclear Information System (INIS)

Hodge, A.M.; Foreman, R.J.; Gallegos, G.F.

2005-01-01

Residual stress analysis was performed on thick, 1-25 μm, depleted uranium (DU) films deposited on an Al substrate by magnetron sputtering. Two distinct characterization techniques were used to measure substrate curvature before and after deposition. Stress evaluation was performed using the Benabdi/Roche equation, which is based on beam theory of a bi-layer material. The residual stress evolution was studied as a function of coating thickness and applied negative bias voltage (0, -200, -300 V). The stresses developed were always compressive; however, increasing the coating thickness and applying a bias voltage presented a trend towards more tensile stresses and thus an overall reduction of residual stresses

Thermoelectric properties of ZnSb films grown by MOCVD

International Nuclear Information System (INIS)

Venkatasubramanian, R.; Watko, E.; Colpitts, T.

1997-04-01

The thermoelectric properties of metallorganic chemical vapor deposited (MOCVD) ZnSb films are reported. The growth conditions necessary to obtain stoichiometric ZnSb films and the effects of various growth parameters on the electrical conductivity and Seebeck coefficients of the films are described. The as-grown ZnSb films are p-type. It was observed that the growth of thicker ZnSb films lead to improved carrier mobilities and lower free-carrier concentrations. The Seebeck coefficient of ZnSb films was found to rise rapidly at approximately 160 to 170 C, with peak Seebeck coefficients as high as 470 microV/K at 220 C. The various growth conditions, including the use of intentional dopants, to improve the Seebeck coefficients at room temperature and above, are discussed. A short annealing of the ZnSb films at temperatures of ∼ 200 C resulted in reduced free-carrier levels and higher Seebeck coefficients at 300 K. Finally, ZT values based on preliminary thermal conductivity measurements using the 3-ω method are reported

Crystalline thin films of transition metal hexacyanochromates grown under Langmuir monolayer

International Nuclear Information System (INIS)

Bagkar, Nitin; Choudhury, Sipra; Kim, Kyung-Hee; Chowdhury, Prasanta; Lee, Sung-Ik; Yakhmi, J.V.

2006-01-01

Crystalline films of cobalt, nickel and iron hexacyanochromates (analogues of Prussian blue) were grown at air-water interface using a surfactant monolayer as a template. These films were transferred on suitable substrates and characterized by X-ray diffraction (XRD), cyclic voltammetry and magnetization measurements. XRD patterns confirmed the formation of oriented crystals in {100} direction for all these films. Magnetization data on nickel and iron hexacyanochromate films indicated ferromagnetic behaviour below Curie temperatures of 72 and 21 K, respectively. The methodology adopted by us to grow crystalline films is useful in obtaining magnetic thin films of analogues of Prussian blue with interesting magnetic properties with respect to transition temperatures and nature of magnetic ordering

The film thickness dependent thermal stability of Al{sub 2}O{sub 3}:Ag thin films as high-temperature solar selective absorbers

Energy Technology Data Exchange (ETDEWEB)

Xiao Xiudi; Xu Gang, E-mail: xiudixiao@163.com; Xiong Bin; Chen Deming; Miao Lei [Chinese Academy of Sciences, Key Laboratory of Renewable Energy and Gas Hydrates, Guangzhou Institute of Energy Conversion (China)

2012-03-15

The monolayer Al{sub 2}O{sub 3}:Ag thin films were prepared by magnetron sputtering. The microstructure and optical properties of thin film after annealing at 700 Degree-Sign C in air were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and spectrophotometer. It revealed that the particle shape, size, and distribution across the film were greatly changed before and after annealing. The surface plasmon resonance absorption and thermal stability of the film were found to be strongly dependent on the film thickness, which was believed to be associated with the evolution process of particle diffusion, agglomeration, and evaporation during annealing at high temperature. When the film thickness was smaller than 90 nm, the film SPR absorption can be attenuated until extinct with increasing annealing time due to the evaporation of Ag particles. While the film thickness was larger than 120 nm, the absorption can keep constant even after annealing for 64 h due to the agglomeration of Ag particles. On the base of film thickness results, the multilayer Al{sub 2}O{sub 3}:Ag solar selective thin films were prepared and the thermal stability test illustrated that the solar selectivity of multilayer films with absorbing layer thickness larger than 120 nm did not degrade after annealing at 500 Degree-Sign C for 70 h in air. It can be concluded that film thickness is an important factor to control the thermal stability of Al{sub 2}O{sub 3}:Ag thin films as high-temperature solar selective absorbers.

Thickness, morphology, and optoelectronic characteristics of pristine and surfactant-modified DNA thin films

International Nuclear Information System (INIS)

Arasu, Velu; Reddy Dugasani, Sreekantha; Son, Junyoung; Gnapareddy, Bramaramba; Ha Park, Sung; Jeon, Sohee; Jeong, Jun-Ho

2017-01-01

Although the preparation of DNA thin films with well-defined thicknesses controlled by simple physical parameters is crucial for constructing efficient, stable, and reliable DNA-based optoelectronic devices and sensors, it has not been comprehensively studied yet. Here, we construct DNA and surfactant-modified DNA thin films by drop-casting and spin-coating techniques. The DNA thin films formed with different control parameters, such as drop-volume and spin-speed at given DNA concentrations, exhibit characteristic thickness, surface roughness, surface potential, and absorbance, which are measured by a field emission scanning electron microscope, a surface profilometer, an ellipsometer, an atomic force microscope, a Kelvin probe force microscope, and an UV–visible spectroscope. From the observations, we realized that thickness significantly affects the physical properties of DNA thin films. This comprehensive study of thickness-dependent characteristics of DNA and surfactant-modified DNA thin films provides insight into the choice of fabrication techniques in order for the DNA thin films to have desired physical characteristics in further applications, such as optoelectronic devices and sensors. (paper)

Thickness-Dependent Surfactant Behavior in Trilayer Polymer Films

Science.gov (United States)

Sun, Yan; Shull, Kenneth; Wang, Jin

2010-03-01

The ability for thin liquid films to wet and remain thermodynamically stable on top of one another is a fundamental challenge in developing high quality paints, coatings, adhesives, and other industrial products. Since intermolecular interactions and interfacial energies dominate in the film thickness regime from tens to hundreds of nanometers, it is desirable to tune these long-range and short-range forces in a simple, controllable manner. Starting from an unstable model homopolymer bilayer (poly(styrene)/poly(4-vinylpyridine)), we demonstrate that sandwiching an additional homopolymer layer (poly(4-bromostyrene)) between the two layers can provide needed surfactancy. As the thickness of this center layer is increased, the full trilayer transitions from unstable (thin) to stable (moderate) to unstable (thick). We experimentally show using x-ray standing waves generated via total external reflection (TER-XSW), atomic force microscopy (AFM), and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) that this behavior can be directly attributed to the autophobic dewetting phenomenon, in which the surfactant layer is thin enough to remain stable but thick enough to shield the neighboring layers, highlighting a general approach to stabilizing multilayer systems.

Kinetics of sub-spinodal dewetting of thin films of thickness dependent viscosity.

Science.gov (United States)

Kotni, Tirumala Rao; Khanna, Rajesh; Sarkar, Jayati

2017-05-04

An alternative explanation of the time varying and very low growth exponents in dewetting of polymer films like polystyrene films is presented based on non-linear simulations. The kinetics of these films is explored within the framework of experimentally observed thickness dependent viscosity. These films exhibit sub-spinodal dewetting via formation of satellite holes in between primary dewetted holes under favorable conditions of excess intermolecular forces and film thicknesses. We find that conditions responsible for sub-spinodal dewetting concurrently lead to remarkable changes in the kinetics of dewetting of even primary holes. For example, the radius of the hole grows in time with a power-law growth exponent sequence of [Formula: see text], in contrast to the usual  ∼4/5. This is due to the cumulative effect of reduced rim mobility due to thickness dependent viscosity and hindrance created by satellite holes.

Photoemission electronic states of epitaxially grown magnetite films

International Nuclear Information System (INIS)

Zalecki, R.; Kolodziejczyk, A.; Korecki, J.; Spiridis, N.; Zajac, M.; Kozlowski, A.; Kakol, Z.; Antolak, D.

2007-01-01

The valence band photoemission spectra of epitaxially grown 300 A single crystalline magnetite films were measured by the angle-resolved ultraviolet photoemission spectroscopy (ARUPS) at 300 K. The samples were grown either on MgO(0 0 1) (B termination) or on (0 0 1) Fe (iron-rich A termination), thus intentionally presenting different surface stoichiometry, i.e. also different surface electronic states. Four main features of the electron photoemission at about -1.0, -3.0, -5.5 and -10.0 eV below a chemical potential show systematic differences for two terminations; this difference depends on the electron outgoing angle. Our studies confirm sensitivity of angle resolved PES technique on subtleties of surface states

Bonding topologies in diamondlike amorphous-carbon films

Energy Technology Data Exchange (ETDEWEB)

SIEGAL,MICHAEL P.; PROVENCIO,PAULA P.; TALLANT,DAVID R.; SIMPSON,REGINA L.; KLEINSORGE,B.; MILNE,W.I.

2000-01-27

The carbon ion energy used during filtered cathodic vacuum arc deposition determines the bonding topologies of amorphous-carbon (a-C) films. Regions of relatively low density occur near the substrate/film and film/surface interfaces and their thicknesses increase with increasing deposition energy. The ion subplantation growth results in mass density gradients in the bulk portion of a-C in the growth direction; density decreases with distance from the substrate for films grown using ion energies < 60 eV and increases for films grown using ion energies > 160 eV. Films grown between these energies are the most diamondlike with relatively uniform bulk density and the highest optical transparencies. Bonding topologies evolve with increasing growth energy consistent with the propagation of subplanted carbon ions inducing a partial transformation of 4-fold to 3-fold coordinated carbon atoms.

Bonding topologies in diamondlike amorphous-carbon films

Energy Technology Data Exchange (ETDEWEB)

Siegal, M. P. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States); Provencio, P. N. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States); Tallant, D. R. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States); Simpson, R. L. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States); Kleinsorge, B. [Department of Engineering, Cambridge University, Cambridge CB2 1PZ, (United Kingdom); Milne, W. I. [Department of Engineering, Cambridge University, Cambridge CB2 1PZ, (United Kingdom)

2000-04-10

The carbon ion energy used during filtered cathodic vacuum arc deposition determines the bonding topologies of amorphous-carbon (a-C) films. Regions of relatively low density occur near the substrate/film and film/surface interfaces; their thicknesses increase with deposition energy. The ion subplantation growth results in mass density gradients in the bulk portion of a-C in the growth direction; density decreases with distance from the substrate for films grown using ion energies <60 eV and increases for films grown using ion energies >160 eV. Films grown between these energies are the most diamondlike with relatively uniform bulk density and the highest optical transparencies. Bonding topologies evolve with increasing growth energy consistent with the propagation of subplanted carbon ions inducing a partial transformation of {sigma}- to {pi}-bonded carbon atoms. (c) 2000 American Institute of Physics.

Lithium ion intercalation into thin film anatase

International Nuclear Information System (INIS)

Kundrata, I.; Froehlich, K.; Ballo, P.

2015-01-01

The aim of this work is to find the optimal parameters for thin film TiO 2 anatase grown by Atomic layer deposition (ALD) for use as electrode in lithium ion batteries. Two parameters, the optimal film thickness and growth conditions are aimed for. Optimal film thickness for achieving optimum between capacity gained from volume and capacity gained by changing of the intercalation constant and optimal growth conditions for film conformity on structured substrates with high aspect ratio. Here we presents first results from this ongoing research and discuss future outlooks. (authors)

Variable angle spectroscopic ellipsometric characterization of HfO2 thin film

Science.gov (United States)

Kumar, M.; Kumari, N.; Karar, V.; Sharma, A. L.

2018-02-01

Hafnium Oxide film was deposited on BK7 glass substrate using reactive oxygenated E-Beam deposition technique. The film was deposited using in-situ quartz crystal thickness monitoring to control the film thickness and rate of evaporation. The thin film was grown with a rate of deposition of 0.3 nm/s. The coated substrate was optically characterized using spectrophotometer to determine its transmission spectra. The optical constants as well as film thickness of the hafnia film were extracted by variable angle spectroscopic ellipsometry with Cauchy fitting at incidence angles of 65˚, 70˚ and 75˚.

Ceramic thick film humidity sensor based on MgTiO3 + LiF

International Nuclear Information System (INIS)

Kassas, Ahmad; Bernard, Jérôme; Lelièvre, Céline; Besq, Anthony; Guhel, Yannick; Houivet, David; Boudart, Bertrand; Lakiss, Hassan; Hamieh, Tayssir

2013-01-01

Graphical abstract: - Highlights: • The fabricated sensor based on MgTiO 3 + LiF materials used the spin coating technology. • The response time is 70 s to detect variation between 5 and 95% relative humidity. • The addition of Scleroglucan controls the viscosity and decreases the roughness of thick film surface. • This humidity sensor is a promising, low-cost, high-quality, reliable ceramic films, that is highly sensitive to humidity. - Abstract: The feasibility of humidity sensor, consisting of a thick layer of MgTiO 3 /LiF materials on alumina substrate, was studied. The thermal analysis TGA-DTGA and dilatometric analysis worked out to confirm the sintering temperature. An experimental plan was applied to describe the effects of different parameters in the development of the thick film sensor. Structural and microstructural characterizations of the developed thick film were made. Rheological study with different amounts of a thickener (scleroglucan “sclg”), showing the behavior variation, as a function of sclg weight % was illustrated and rapprochement with the results of thickness variation as a function of angular velocity applied in the spin coater. The electrical and dielectric measurements confirmed the sensitivity of the elaborated thick film against moisture, along with low response time

Influence of Liquid Petroleum Gas on the Electrical Parameters of the WO3 Thick Film

Directory of Open Access Journals (Sweden)

R. S. KHADAYATE

2007-02-01

Full Text Available In this work, the WO3 thick films were prepared by standard screen-printing technology. These films were characterized by x-ray diffraction (XRD measurements and scanning electron microscopy (SEM. Influence of LPG on the electrical properties of the prepared WO3 thick film is reported. It was observed that the slope of the Arrhenius curves of the WO3 thick film decreased as the medium changed from pure air to 100 ppm LPG in air. From I-V characteristics, it was observed that the WO3 thick film exhibit highest sensitivity to 50 ppm LPG in air at 400oC.

A method for reducing the sloughing of thick blood films for malaria diagnosis.

Science.gov (United States)

Norgan, Andrew P; Arguello, Heather E; Sloan, Lynne M; Fernholz, Emily C; Pritt, Bobbi S

2013-07-08

The gold standard for malaria diagnosis is the examination of thick and thin blood films. Thick films contain 10 to 20 times more blood than thin films, correspondingly providing increased sensitivity for malaria screening. A potential complication of thick film preparations is sloughing of the blood droplet from the slide during staining or rinsing, resulting in the loss of sample. In this work, two methods for improving thick film slide adherence ('scratch' (SCM) and 'acetone dip' (ADM) methods) were compared to the 'standard method' (SM) of thick film preparation. Standardized blood droplets from 26 previously examined EDTA whole blood specimens (22 positive and four negative) were concurrently spread on glass slides using the SM, ADM, and SCM. For the SM and ADM prepared slides, the droplet was gently spread to an approximate 22 millimeters in diameter spot on the slide using the edge of a second glass slide. For the SCM, the droplet was spread by carefully grinding (or scratching) it into the slide with the point of a second glass slide. Slides were dried for one hour in a laminar flow hood. For the ADM, slides were dipped once in an acetone filled Coplin jar and allowed to air dry. All slides were then Giemsa-stained and examined in a blinded manner. Adherence was assessed by blinded reviewers. No significant or severe defects were observed for slides prepared with the SCM. In contrast, 8 slides prepared by the ADM and 3 prepared using the SM displayed significant or severe defects. Thick films prepared by the three methods were microscopically indistinguishable and concordant results (positive or negative) were obtained for the three methods. Estimated parasitaemia of the blood samples ranged from 25 to 429,169 parasites/μL of blood. The SCM is an inexpensive, rapid, and simple method that improves the adherence of thick blood films to standard glass slides without altering general slide preparation, microscopic appearance or interpretability. Using the SCM

Simultaneous reflectometry and interferometry for measuring thin-film thickness and curvature

Science.gov (United States)

Arends, A. A.; Germain, T. M.; Owens, J. F.; Putnam, S. A.

2018-05-01

A coupled reflectometer-interferometer apparatus is described for thin-film thickness and curvature characterization in the three-phase contact line region of evaporating fluids. Validation reflectometry studies are provided for Au, Ge, and Si substrates and thin-film coatings of SiO2 and hydrogel/Ti/SiO2. For interferometry, liquid/air and solid/air interferences are studied, where the solid/air samples consisted of glass/air/glass wedges, cylindrical lenses, and molded polydimethylsiloxane lenses. The liquid/air studies are based on steady-state evaporation experiments of water and isooctane on Si and SiO2/Ti/SiO2 wafers. The liquid thin-films facilitate characterization of both (i) the nano-scale thickness of the absorbed fluid layer and (ii) the macro-scale liquid meniscus thickness, curvature, and curvature gradient profiles. For our validation studies with commercial lenses, the apparatus is shown to measure thickness profiles within 4.1%-10.8% error.

Characterization and comparison of thermistor thick films. Topical report

International Nuclear Information System (INIS)

Gehman, R.W.

1981-09-01

Four thermistor thick film inks were evaluated for HMC production use. The physical, chemical and electrical properties of the wet inks and fired films were measured. Variations in the physical and chemical properties of the inks were used to explain variations in thermistor electrical resistance and temperature coefficient of resistance

Ultrathin NbN Films for Superconducting Single-Photon Detectors

International Nuclear Information System (INIS)

Slysz, W.; Guziewicz, M.; Borysiewicz, M.

2011-01-01

We present our research on fabrication and structural and transport characterization of ultrathin superconducting NbN layers deposited on both single-crystal Al 2 O 3 and Si wafers, and SiO 2 and Si 3 N 4 buffer layers grown directly on Si wafers. The thicknesses of our films varied from 6 nm to 50 nm and they were grown using reactive RF magnetron sputtering on substrates maintained at the temperature 850 o C. We have performed extensive morphology characterization of our films using the X-ray diffraction method and atomic force microscopy, and related the results to the type of the substrate used for the film deposition. Our transport measurements showed that even the thinnest, 6 nm thick NbN films had the superconducting critical temperature of 10-12 K, which was increased to 14 K for thicker films. (author)

Magnetic properties of ultrathin Co/Ge(111) and Co/Ge(100) films

International Nuclear Information System (INIS)

Cheng, W. C.; Tsay, J. S.; Yao, Y. D.; Lin, K. C.; Yang, C. S.; Lee, S. F.; Tseng, T. K.; Neih, H. Y.

2001-01-01

The orientation of the magnetization and the occurrence of interfacial ferromagnetic inactive layers for ultrathin Co films grown on Ge(111) and Ge(100) surfaces have been studied using the in situ surface magneto-optic Kerr effect. On a Ge(111) substrate, cobalt films (≤28 monolayers) with in-plane easy axis of magnetization have been observed; however, on a Ge(100) substrate, ultrathin Co films (14 - 16 monolayers) with canted out-of-plane easy axis of magnetization were measured. The ferromagnetic inactive layers were formed due to the intermixing of Co and Ge and lowering the Curie temperature by reducing Co film thickness. The Co - Ge compound inactive layers were 3.8 monolayers thick for Co films grown on Ge(111) and 6.2 monolayers thick for Co films deposited on Ge(100). This is attributed to the difference of the density of surface atoms on Ge(111) and Ge(100). [copyright] 2001 American Institute of Physics

Influence of colorant and film thickness on thermal aging characteristics of oxo-biodegradable plastic bags

Science.gov (United States)

Leuterio, Giselle Lou D.; Pajarito, Bryan B.; Domingo, Carla Marie C.; Lim, Anna Patricia G.

2016-05-01

Functional, lightweight, strong and cheap plastic bags incorporated with pro-oxidants undergo accelerated degradation under exposure to heat and oxygen. This work investigated the effect of colorant and film thickness on thermal aging characteristics of commercial oxo-biodegradable plastic bag films at 70 °C. Degradation is monitored through changes in infrared absorption, weight, and tensile properties of thermally aged films. The presence of carbonyl band in infrared spectrum after 672 h of thermal aging supports the degradation behavior of exposed films. Results show that incorporation of colorant and increasing thickness exhibit low maximum weight uptake. Titanium dioxide as white colorant in films lowers the susceptibility of films to oxygen uptake but enhances physical degradation. Higher amount of pro-oxidant loading also contributes to faster degradation. Opaque films are characterized by low tensile strength and high elastic modulus. Decreasing the thickness contributes to lower tensile strength of films. Thermally aged films with colorant and low thickness promote enhanced degradation.

Thickness control in electrophoretic deposition of WO{sub 3} nanofiber thin films for solar water splitting

Energy Technology Data Exchange (ETDEWEB)

Fang, Yuanxing; Lee, Wei Cheat; Canciani, Giacomo E.; Draper, Thomas C.; Al-Bawi, Zainab F. [Department of Chemistry, School of Life Sciences, University of Sussex, Brighton BN1 9QJ (United Kingdom); Bedi, Jasbir S. [School of Public Health & Zoonoses, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana 141004 Punjab (India); Perry, Christopher C. [Division of Biochemistry, School of Medicine, Loma Linda University, Loma Linda, CA 92350 (United States); Chen, Qiao, E-mail: qiao.chen@sussex.ac.uk [Department of Chemistry, School of Life Sciences, University of Sussex, Brighton BN1 9QJ (United Kingdom)

2015-12-15

Graphical abstract: - Highlights: • A novel method combining electrospinning and electrophoretic deposition was established for the creation of nanostructured semiconductor thin films. • The created thin films displayed a high chemical stability with a controllable thickness. • The PEC water splitting performance of the thin films was optimized by fine-tuning the thickness of the films. • A maximum photoconversion efficiency was achieved by 18 μm nanofibrous thin films. - Abstract: Electrophoretic deposition (EPD) of ground electrospun WO{sub 3} nanofibers was applied to create photoanodes with controlled morphology for the application of photoelectrochemical (PEC) water splitting. The correlations between deposition parameters and film thicknesses were investigated with theoretical models to precisely control the morphology of the nanostructured porous thin film. The photoconversion efficiency was further optimized as a function of film thickness. A maximum photoconversion efficiency of 0.924% from electrospun WO{sub 3} nanofibers that EPD deposited on a substrate was achieved at a film thickness of 18 μm.

Structural and optical properties of ZnO films grown on silicon and ...

Indian Academy of Sciences (India)

TECS

Abstract. Photoluminescence (PL) properties of undoped ZnO thin films grown by rf magnetron sputtering on silicon .... voluted O1 s and (c) typical Zr 3d spectra of ZrO2/ZnO/Si film. .... strate doping concentration (NB) of ≈ 2⋅5 × 1015 cm–3 is.

Nanoporous-carbon films for microsensor preconcentrators

Science.gov (United States)

Siegal, M. P.; Overmyer, D. L.; Kottenstette, R. J.; Tallant, D. R.; Yelton, W. G.

2002-05-01

Nanoporous-carbon (NPC) films are grown using physical processes such as low-power pulsed-laser deposition with attenuation of the ablated carbon species kinetic energy attained by using an inert background gas. With room-temperature growth and negligible residual stress, NPC can coat nearly any substrate to any desired thickness. Control of the deposition energetics yields precise morphology, density, and hence, porosity, with no discernable variation in chemical bonding. We produce NPC films 8 μm thick with density <0.2 g/cm3. The well-controlled porosity, i.e., available surface area, is demonstrated by using films with different thicknesses as a preconcentrator for a nerve-gas simulant.

Multifunctional thick-film structures based on spinel ceramics for environment sensors

Energy Technology Data Exchange (ETDEWEB)

Vakiv, M; Hadzaman, I; Klym, H; Shpotyuk, O [Institute of Materials of SRC ' Carat' , 202 Stryjska str., Lviv, 79031 (Ukraine); Brunner, M, E-mail: shpotyuk@novas.lviv.ua, E-mail: klymha@yahoo.com [Fachhochschule Koeln/University of Applied Sciences, 2 Betzdorfer str., Koeln, 50679 (Germany)

2011-04-01

Temperature sensitive thick films based on spinel-type NiMn{sub 2}O{sub 4}-CuMn{sub 2}O{sub 4}-MnCo{sub 2}O{sub 4} manganites with p- and p{sup +}-types of electrical conductivity and their multilayer p{sup +}-p structures were studied. These thick-film elements possess good electrophysical characteristics before and after long-term ageing test at 170 deg. C. It is shown that degradation processes connected with diffusion of metallic Ag into film grain boundaries occur in one-layer p-and p{sup +}-conductive films. Some part of the p{sup +}-p structures were of high stability, the relative electrical drift being no more than 1 %.

Thickness determination of large-area films of yttria-stabilized zirconia produced by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Pryds, N. [Materials Research Department, Riso National Laboratory, DK-4000 Roskilde (Denmark)]. E-mail: nini.pryds@risoe.dk; Toftmann, B. [Department of Optics and Plasma Research, Riso National Laboratory, DK-4000 Roskilde (Denmark); Bilde-Sorensen, J.B. [Materials Research Department, Riso National Laboratory, DK-4000 Roskilde (Denmark); Schou, J. [Department of Optics and Plasma Research, Riso National Laboratory, DK-4000 Roskilde (Denmark); Linderoth, S. [Materials Research Department, Riso National Laboratory, DK-4000 Roskilde (Denmark)

2006-04-30

Films of yttria-stabilized zirconia (YSZ) on a polished silicon substrate of diameter up to 125 mm have been produced in a large-area pulsed laser deposition (PLD) setup under typical PLD conditions. The film thickness over the full film area has been determined by energy-dispersive X-ray spectrometry in a scanning electron microscope (SEM) with use of a method similar to one described by Bishop and Poole. The attenuation of the electron-induced X-rays from the Si wafer by the film was monitored at a number of points along a diameter and the thickness was determined by Monte Carlo simulations of the attenuation for various values of film thickness with the program CASINO. These results have been compared with direct measurements in the SEM of the film thickness on a cross-section on one of the wafers. The results of these measurements demonstrate the ability of this technique to accurately determine the thickness of a large film, i.e. up to diameters of 125 mm, in a relatively short time, without destroying the substrate, without the need of a standard sample and without the need of a flat substrate. We have also demonstrated that by controlling the deposition parameters large-area YSZ films with uniform thickness can be produced.

Thickness determination of large-area films of yttria-stabilized zirconia produced by pulsed laser deposition

International Nuclear Information System (INIS)

Pryds, N.; Toftmann, B.; Bilde-Sorensen, J.B.; Schou, J.; Linderoth, S.

2006-01-01

Films of yttria-stabilized zirconia (YSZ) on a polished silicon substrate of diameter up to 125 mm have been produced in a large-area pulsed laser deposition (PLD) setup under typical PLD conditions. The film thickness over the full film area has been determined by energy-dispersive X-ray spectrometry in a scanning electron microscope (SEM) with use of a method similar to one described by Bishop and Poole. The attenuation of the electron-induced X-rays from the Si wafer by the film was monitored at a number of points along a diameter and the thickness was determined by Monte Carlo simulations of the attenuation for various values of film thickness with the program CASINO. These results have been compared with direct measurements in the SEM of the film thickness on a cross-section on one of the wafers. The results of these measurements demonstrate the ability of this technique to accurately determine the thickness of a large film, i.e. up to diameters of 125 mm, in a relatively short time, without destroying the substrate, without the need of a standard sample and without the need of a flat substrate. We have also demonstrated that by controlling the deposition parameters large-area YSZ films with uniform thickness can be produced

Micro-machined high-frequency (80 MHz) PZT thick film linear arrays.

Science.gov (United States)

Zhou, Qifa; Wu, Dawei; Liu, Changgeng; Zhu, Benpeng; Djuth, Frank; Shung, K

2010-10-01

This paper presents the development of a micromachined high-frequency linear array using PZT piezoelectric thick films. The linear array has 32 elements with an element width of 24 μm and an element length of 4 mm. Array elements were fabricated by deep reactive ion etching of PZT thick films, which were prepared from spin-coating of PZT sol-gel composite. Detailed fabrication processes, especially PZT thick film etching conditions and a novel transferring-and-etching method, are presented and discussed. Array designs were evaluated by simulation. Experimental measurements show that the array had a center frequency of 80 MHz and a fractional bandwidth (-6 dB) of 60%. An insertion loss of -41 dB and adjacent element crosstalk of -21 dB were found at the center frequency.

Indium-Nitrogen Codoped Zinc Oxide Thin Film Deposited by Ultrasonic Spray Pyrolysis on n-(111 Si Substrate: The Effect of Film Thickness

Directory of Open Access Journals (Sweden)

Cheng-Chang Yu

2014-01-01

Full Text Available Indium-nitrogen codoped zinc oxide (INZO thin films were fabricated by spray pyrolysis deposition technique on n-(111 Si substrate with different film thicknesses at 450°C using a precursor containing zinc acetate, ammonium acetate, and indium nitrate with 1 : 3 : 0.05 at.% concentration. The morphology and structure studies were carried out by scanning electron microscopy (SEM and X-ray diffraction (XRD. The grain size of the films increased when increasing the film thickness. From XRD spectra, polycrystalline ZnO structure can be observed and the preferred orientation behavior varied from (002 to (101 as the film thickness increased. The concentration and mobility were investigated by Hall effect measurement. the p-type films with a hole mobility around 3 cm2V−1s−1 and hole concentration around 3×1019 cm−3 can be achieved with film thickness less than 385 nm. The n-type conduction with concentration 1×1020 cm−3 is observed for film with thickness 1089 nm. The defect states were characterized by photoluminescence. With temperature-dependent conductivity analysis, acceptor state with activation energy 0.139 eV dominate the p type conduction for thin INZO film. And the Zn-related shallow donors with activation energy 0.029 eV dominate the n-type conduction for the thick INZO film.

Comparison of functional parameters of CsI:Tl crystals and thick films

International Nuclear Information System (INIS)

Fedorov, A.; Gektin, A.; Lebedynskiy, A.; Mateychenko, P.; Shkoropatenko, A.

2013-01-01

500 mkm thick CsI:Tl columnar films can be produced using thermal evaporation in vacuum by sublimation of the same bulk crystal. Comparison of afterglow and radiation stability of deposited CsI:Tl films with source crystal was the aim of current work. It is shown that the afterglow in the films is always below its level in initial single crystal. It was ascertained that the annealing atmospheres influence the processes leading to the activator depletion of the films during the thermal processing. -- Highlights: ► Thick CsI:Tl columnar films were obtained by thermal evaporation in vacuum. ► Radiation stability of such CsI:Tl films appears to be better than that of crystal. ► CsI:Tl film parameters can be modified by annealing in different atmospheres

Thickness and microstructure effects in the optical and electrical properties of silver thin films

Energy Technology Data Exchange (ETDEWEB)

Ding, Guowen, E-mail: gding@intermolecular.com; Clavero, César; Schweigert, Daniel; Le, Minh [Intermolecular, Inc., 3011 North First Street, San Jose, CA 95134 (United States)

2015-11-15

The optical and electrical response of metal thin films approaching thicknesses in the range of the electron mean free path is highly affected by electronic scattering with the interfaces and defects. Here, we present a theoretical and experimental study on how thickness and microstructure affect the properties of Ag thin films. We are able to successfully model the electrical resistivity and IR optical response using a thickness dependent electronic scattering time. Remarkably, the product of electronic scattering time and resistivity remains constant regardless of the thickness (τx ρ = C), with a value of 59 ± 2 μΩ cm ⋅ fs for Ag films in the investigated range from 3 to 74 nm. Our findings enable us to develop a theoretically framework that allows calculating the optical response of metal thin films in the IR by using their measured thickness and resistivity. An excellent agreement is found between experimental measurements and predicted values. This study also shows the theoretical lower limit for emissivity in Ag thin films according to their microstructure and thickness. Application of the model presented here will allow rapid characterization of the IR optical response of metal thin films, with important application in a broad spectrum of fundamental and industrial applications, including optical coatings, low-emissivity windows and semiconductor industry.

Structural, magnetic and transport properties of Co2FeAl Heusler films with varying thickness

International Nuclear Information System (INIS)

Wang, Xiaotian; Li, Yueqing; Du, Yin; Dai, Xuefang; Liu, Guodong; Liu, Enke; Liu, Zhongyuan; Wang, Wenhong; Wu, Guangheng

2014-01-01

We report on a systematic study of the structural, magnetic properties and the anomalous Hall effect, in the Heusler alloy Co 2 FeAl (CFA) epitaxial films on MgO (001), as a function of film thickness. It was found that the epitaxial CFA films show a highly ordered B2 structure with an in-plane uniaxial magnetic anisotropy. The electrical transport properties reveal that the lattice and magnon scattering contributions to the longitudinal resistivity. Independent on the thickness of films, the anomalous Hall resistivity of CFA films is found to be dominated by skew scattering only. Moreover, the anomalous Hall resistivity shows weakly temperature dependent behavior, and its absolute value increases as the thickness decreases. We attribute this temperature insensitivity in the anomalous Hall resistivity to the weak temperature dependent of tunneling spin-polarization in the CFA films, while the thickness dependence behavior is likely due to the increasing significance of interface or free surface electronic states. - Highlights: ●Highly ordered CFA films with various thicknesses were prepared on MgO substrates. ●The magnon scattering contributions to the longitudinal resistivity in the CFA films. ●The anomalous Hall resistivity of the CFA films shows weakly temperature dependent. ●The CFA films show weak temperature dependent of tunneling spin-polarization

Incorporation of La in epitaxial SrTiO{sub 3} thin films grown by atomic layer deposition on SrTiO{sub 3}-buffered Si (001) substrates

Energy Technology Data Exchange (ETDEWEB)

McDaniel, Martin D.; Ngo, Thong Q.; Ekerdt, John G., E-mail: ekerdt@utexas.edu [University of Texas at Austin, Department of Chemical Engineering, Austin, Texas 78712 (United States); Posadas, Agham; Demkov, Alexander A. [University of Texas at Austin, Department of Physics, Austin, Texas 78712 (United States); Karako, Christine M. [University of Dallas, Department of Chemistry, Irving, Texas 75062 (United States); Bruley, John; Frank, Martin M.; Narayanan, Vijay [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States)

2014-06-14

Strontium titanate, SrTiO{sub 3} (STO), thin films incorporated with lanthanum are grown on Si (001) substrates at a thickness range of 5–25 nm. Atomic layer deposition (ALD) is used to grow the La{sub x}Sr{sub 1−x}TiO{sub 3} (La:STO) films after buffering the Si (001) substrate with four-unit-cells of STO deposited by molecular beam epitaxy. The crystalline structure and orientation of the La:STO films are confirmed via reflection high-energy electron diffraction, X-ray diffraction, and cross-sectional transmission electron microscopy. The low temperature ALD growth (∼225 °C) and post-deposition annealing at 550 °C for 5 min maintains an abrupt interface between Si (001) and the crystalline oxide. Higher annealing temperatures (650 °C) show more complete La activation with film resistivities of ∼2.0 × 10{sup −2} Ω cm for 20-nm-thick La:STO (x ∼ 0.15); however, the STO-Si interface is slightly degraded due to the increased annealing temperature. To demonstrate the selective incorporation of lanthanum by ALD, a layered heterostructure is grown with an undoped STO layer sandwiched between two conductive La:STO layers. Based on this work, an epitaxial oxide stack centered on La:STO and BaTiO{sub 3} integrated with Si is envisioned as a material candidate for a ferroelectric field-effect transistor.

Thickness-Dependent Order-to-Order Transitions of Bolaform-like Giant Surfactant in Thin Films

Energy Technology Data Exchange (ETDEWEB)

Hsu, Chih-Hao; Yue, Kan; Wang, Jing; Dong, Xue-Hui; Xia, Yanfeng; Jiang, Zhang [X-ray; Thomas, Edwin L. [Department; Cheng, Stephen Z. D.

2017-09-07

Controlling self-assembled nanostructures in thin films allows the bottom-up fabrication of ordered nanoscale patterns. Here we report the unique thickness-dependent phase behavior in thin films of a bolaform-like giant surfactant, which consists of butyl- and hydroxyl-functionalized polyhedral oligomeric silsesquioxane (BPOSS and DPOSS) cages telechelically located at the chain ends of a polystyrene (PS) chain with 28 repeating monomers on average. In the bulk, BPOSS-PS28-DPOSS forms a double gyroid (DG) phase. Both grazing incidence small angle X-ray scattering and transmission electron microscopy techniques are combined to elucidate the thin film structures. Interestingly, films with thicknesses thinner than 200 nm exhibit an irreversible phase transition from hexagonal perforated layer (HPL) to compressed hexagonally packed cylinders (c-HEX) at 130 °C, while films with thickness larger than 200 nm show an irreversible transition from HPL to DG at 200 °C. The thickness-controlled transition pathway suggests possibilities to obtain diverse patterns via thin film self-assembly.

Critical current density and microstructure of YBa2Cu3O7-x films as a function of film thickness

International Nuclear Information System (INIS)

Mogro-Campero, A.; Turner, L.G.; Hall, E.L.; Lewis, N.

1990-01-01

Thin films of nominal composition YBa 2 Cu 3 O 7-x (YBCO) were produced on (100) SrTiO 3 substrates by coevaporation and furnace annealing. Film thicknesses in the range of 0.2 to 2.4 μm were analyzed. Microstructural investigations by cross sectional transmission electron microscopy (TEM) reveal a continuous layer of about 0.4 μm thickness adjacent to the substrate with c-axis normal to the substrate plane. In thicker films the remaining top portion has the c-axis in the film plane. The critical current density (J c ) at 77 K decreases with increasing thickness in the thickness range exceeding 0.4 μm, qualitatively consistent with the microstructural observation, but quantitatively inconsistent with a simple model based on the microstructural data

Effects of substrate material on carbon films grown by laser molecular beam epitaxy

International Nuclear Information System (INIS)

Liu, M.; Xu, X.Y.; Man, B.Y.; Kong, D.M.; Xu, S.C.

2012-01-01

Highlights: ► We prepared tri-layers by laser molecular beam epitaxy (LMBE) on sapphire substrate. ► We found that the formation of the graphene film has a strong relation to the structure and properties of the substrate. ► The different carbon film formation mechanism of the buffer layers can affect the morphology of the film. - Abstract: The carbon thin films were grown on different substrates with different buffer layers by laser molecular beam epitaxy (LMBE) with a high purity graphite carbon target. A UV pulsed KrF excimer laser with a wavelength of 248 nm was used as laser source. The structure, surface morphology and other properties of the carbon thin films were characterized by Raman spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED) and atomic force microscopy (AFM). The results show that the properties of the carbon thin films and the formation of the graphene film have a strong relation to the structure and properties of the substrate. The substrate with a hexagonal wurtzite structure which is similar to the hexagonal honeycomb structure of the carbon atoms arranged in the graphene is more beneficial for the formation of the graphene thin film. In our experiment conditions, the carbon films grown on sapphire substrates with different buffer layers have an ordered structure and a smooth surface, and form high quality tri-layer graphene films.

Nitrogen lattice location in MOVPE grown Ga1-xInxNyAs1-y films using ion beam channeling

International Nuclear Information System (INIS)

Nebiki, Takuya; Narusawa, Tadashi; Kumagai, Akiko; Doi, Hideyuki; Saito, Tadashi; Takagishi, Shigenori

2006-01-01

We have investigated the nitrogen lattice location in MOVPE grown Ga 1-x In x N y As 1-y with x=0.07 and y=0.025 by means of ion beam channeling technique. In this system, the lattice constant of the Ga 1-x In x N y As 1-y film is equal to GaAs lattice. Therefore, we can grow apparently no strain, high quality and very thick GaInNAs film on GaAs substrate. The quality of the films as well as the lattice location of In and N were characterized by channeling Rutherford backscattering spectrometry and nuclear reaction analysis using 3.95 MeV He 2+ beam. The fraction of substitutional nitrogen in the film was measured using the 14 N(α,p) 17 O endothermic nuclear reaction. Our results indicate that more than 90% of In and N atoms are located the substitutional site, however, N atoms are slightly displaced by ∼0.2 A from the lattice site. We suggest that the GaInNAs film has a local strain or point defects around the N atoms. (author)

Effects of rework on adhesion of Pb-In soldered gold thick films

International Nuclear Information System (INIS)

Gehman, R.W.; Becka, G.A.; Losure, J.A.

1982-02-01

The feasibility of repeatedly reworking Pb-In soldered joints on gold thick films was evaluated. Nailhead adhesion tests on soldered thick films typically resulted in failure within the bulk solder (50 In-50 Pb). Average strengths increased with each rework, and the failure mode changed. An increase in metalization lift-off occurred with successive reworks. An investigation was initiated to determine why these changes occurred. Based on this work, the thick film adhesion to the substrate appeared to be lowered by indium reduction of cadmium oxide and by formation of a weak, brittle intermetallic compound, Au 9 In 4 . It was concluded that two solder reworks could be conducted without significant amounts of metallization lift-off during nailhead testing

Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of ultrathin block copolymer films.

Science.gov (United States)

Huang, Changchun; Wen, Gangyao; Li, Jingdan; Wu, Tao; Wang, Lina; Xue, Feifei; Li, Hongfei; Shi, Tongfei

2016-09-15

Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of spin-coated polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films (dewetting of the films with different thicknesses occur via the spinodal dewetting and the nucleation and growth mechanisms, respectively. The PS-b-PMMA films rupture into droplets which first coalesce into large ones to reduce the surface free energy. Then the large droplets rupture into small ones to increase the contact area between PMMA blocks and acetone molecules resulting from ultimate migration of PMMA blocks to droplet surface, which is a novel dewetting process observed in spin-coated films for the first time. Copyright © 2016 Elsevier Inc. All rights reserved.

Influence of substrate and film thickness on polymer LIPSS formation

Energy Technology Data Exchange (ETDEWEB)

Cui, Jing; Nogales, Aurora; Ezquerra, Tiberio A. [Instituto de Estructura de la Materia (IEM-CSIC), Serrano 121, Madrid 28006 (Spain); Rebollar, Esther, E-mail: e.rebollar@csic.es [Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, Madrid 28006 (Spain)

2017-02-01

Highlights: • The estimation of temperature upon pulse accumulation shows that a small positive offset is caused by each individual pulse. • Number of pulses needed for LIPSS formation in PS thin films depends on polymer thickness. • Thermal conductivity and diffusivity of supporting substrate influence the onset for LIPSS formation and their quality. • Quality of LIPSS is affected by the substrate optical properties. - Abstract: Here we focus on the influence of both, substrate and film thickness on polymer Laser Induced Periodic Surface Structures (LIPSS) formation in polymer films. For this aim a morphological description of ripples structures generated on spin-coated polystyrene (PS) films by a linearly polarized laser beam with a wavelength of 266 nm is presented. The influence of different parameters on the quality and characteristics of the formed laser-induced periodic surface structures (LIPSS) was investigated. We found that well-ordered LIPSS are formed either on PS films thinner than 200 nm or thicker than 400 nm supported on silicon substrates as well as on thicker free standing films. However less-ordered ripples are formed on silicon supported films with intermediate thicknesses in the range of 200–380 nm. The effect of the thermal and optical properties of the substrate on the quality of LIPSS was analyzed. Differences observed in the fluence and number of pulses needed for the onset of surface morphological modifications is explained considering two main effects which are: (1) The temperature increase on polymer surface induced by the action of cumulative laser irradiation and (2) The differences in thermal conductivity between the polymer and the substrate which strongly affect the heat dissipation generated by irradiation.

Electron beam curable polymer thick film

International Nuclear Information System (INIS)

Nagata, Hidetoshi; Kobayashi, Takashi

1988-01-01

Currently, most printed circuit boards are produced by the selective etching of copper clads laminated on dielectric substrates such as paper/phenolic resion or nonwoven glass/epoxy resin composites. After the etchig, various components such as transistors and capacitors are mounted on the boards by soldering. But these are troublesome works, therefore, as an alternative, printing method has been investigated recently. In the printing method, conductor circuits and resistors can be made by printing and curing of the specially prepared paste on dielectric substrates. In the near future, also capacitors are made by same method. Usually, conductor paste, resistor paste and dielectric paste are employed, and in this case, the printing is screen printing, and the curing is done thermally. In order to avoid heating and the deterioration of substrates, attention was paid to electron beam curing, and electron beam curable polymer thick film system was developed. The electron beam curable paste is the milled mixture of a filler and an electron beam curable binder of oligomer/monomer. The major advantage of electron beam curable polymer thick film, the typical data of a printed resistor of this type and its trial are reported. (K.I.)

Investigation of structure, adhesion strength, wear performance and corrosion behavior of platinum/ruthenium/nitrogen doped diamond-like carbon thin films with respect to film thickness

Energy Technology Data Exchange (ETDEWEB)

Khun, N.W. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Liu, E., E-mail: MEJLiu@ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

2011-03-15

Research highlights: {yields} Sputtered PtRuN-DLC thin films were fabricated with different film thicknesses. {yields} The graphitization of the films increased with increased film thickness. {yields} The wear resistance of the films increased though their adhesion strength decreased. {yields} The corrosion potentials of the films shifted to more negative values. {yields} However, the corrosion currents of the films decreased. - Abstract: In this study, the corrosion performance of platinum/ruthenium/nitrogen doped diamond-like carbon (PtRuN-DLC) thin films deposited on p-Si substrates using a DC magnetron sputtering deposition system in a 0.1 M NaCl solution was investigated using potentiodynamic polarization test in terms of film thickness. The effect of the film thickness on the chemical composition, bonding structure, surface morphology, adhesion strength and wear resistance of the PtRuN-DLC films was studied using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM), micro-scratch test and ball-on-disc tribotest, respectively. It was found that the wear resistance of the PtRuN-DLC films apparently increased with increased film thickness though the adhesion strength of the films decreased. The corrosion results revealed that the increased concentration of sp{sup 2} bonds in the PtRuN-DLC films with increased film thickness shifted the corrosion potentials of the films to more negative values but the decreased porosity density in the films significantly decreased the corrosion currents of the films.

Investigation of structure, adhesion strength, wear performance and corrosion behavior of platinum/ruthenium/nitrogen doped diamond-like carbon thin films with respect to film thickness

International Nuclear Information System (INIS)

Khun, N.W.; Liu, E.

2011-01-01

Research highlights: → Sputtered PtRuN-DLC thin films were fabricated with different film thicknesses. → The graphitization of the films increased with increased film thickness. → The wear resistance of the films increased though their adhesion strength decreased. → The corrosion potentials of the films shifted to more negative values. → However, the corrosion currents of the films decreased. - Abstract: In this study, the corrosion performance of platinum/ruthenium/nitrogen doped diamond-like carbon (PtRuN-DLC) thin films deposited on p-Si substrates using a DC magnetron sputtering deposition system in a 0.1 M NaCl solution was investigated using potentiodynamic polarization test in terms of film thickness. The effect of the film thickness on the chemical composition, bonding structure, surface morphology, adhesion strength and wear resistance of the PtRuN-DLC films was studied using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM), micro-scratch test and ball-on-disc tribotest, respectively. It was found that the wear resistance of the PtRuN-DLC films apparently increased with increased film thickness though the adhesion strength of the films decreased. The corrosion results revealed that the increased concentration of sp 2 bonds in the PtRuN-DLC films with increased film thickness shifted the corrosion potentials of the films to more negative values but the decreased porosity density in the films significantly decreased the corrosion currents of the films.

MOVPE of InN films on GaN templates grown on sapphire and silicon(111) substrates

International Nuclear Information System (INIS)

Jamil, Muhammad; Arif, Ronald A.; Ee, Yik-Khoon; Tong, Hua; Tansu, Nelson; Higgins, John B.

2008-01-01

This paper reports the study of MOVPE of InN on GaN templates grown on sapphire and silicon(111) substrates. Thermodynamic analysis of MOVPE of InN performed using NH 3 as nitrogen source and the experimental findings support the droplet-free epitaxial growth of InN under high V/III ratios of input precursors. At a growth pressure of 500 Torr, the optimum growth temperature and V/III ratio of the InN film are 575-650 C and >3 x 10 5 , respectively. The surface RMS roughness of InN film grown GaN/sapphire template is ∝0.3 nm on 2 μm x 2 μm area, while the RMS roughness of the InN film grown on GaN/Si(111) templates is found as ∝0.7 nm. The X-ray diffraction (XRD) measurement reveals the (0002) texture of the InN film on GaN/sapphire template with a FWHM of 281 arcsec of the InN(0002) ω rocking curve. For the film grown on GaN/Si template under identical growth conditions, the XRD measurements show the presence of metallic In, in addition to the (0002) orientation of InN layer. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Effect of diffusion on percolation threshold in thick-film resistors

International Nuclear Information System (INIS)

Abdurakhmanov, G.

2009-01-01

Resistivity ρ(C) of thick-film resistors doped by metal oxides is simulated as a function of volume content C of the ligature, firing temperature T f and firing time τ. It is proved that the doping of a glass during firing of the thick film resistor is rather uniform. It is shown also, that conductance takes place in the whole volume of the sample, but not through the sole infinite cluster only, even the content of a conductive phase is below than the theoretical percolation threshold value.

Atomic layer deposition of a MoS₂ film.

Science.gov (United States)

Tan, Lee Kheng; Liu, Bo; Teng, Jing Hua; Guo, Shifeng; Low, Hong Yee; Tan, Hui Ru; Chong, Christy Yuen Tung; Yang, Ren Bin; Loh, Kian Ping

2014-09-21

A mono- to multilayer thick MoS₂ film has been grown by using the atomic layer deposition (ALD) technique at 300 °C on a sapphire wafer. ALD provides precise control of the MoS₂ film thickness due to pulsed introduction of the reactants and self-limiting reactions of MoCl₅ and H₂S. A post-deposition annealing of the ALD-deposited monolayer film improves the crystallinity of the film, which is evident from the presence of triangle-shaped crystals that exhibit strong photoluminescence in the visible range.

Photo-induced wettability of TiO{sub 2} film with Au buffer layer

Energy Technology Data Exchange (ETDEWEB)

Purkayastha, Debarun Dhar; Sangani, L. D. Varma; Krishna, M. Ghanashyam [School of Physics, University of Hyderabad, Hyderabad-500046 (India); Madhurima, V., E-mail: madhurima.v@gmail.com [Department of Physics, Central University of Tamil Nadu, Thiruvarur-610004 (India)

2014-04-24

The effect of thickness of Au buffer layer (15-25 nm) between TiO{sub 2} film and substrate on the wettability of TiO{sub 2} films is reported. TiO{sub 2} films grown on Au buffer layer have a higher contact angle of 96-;100° as compared to 47.6o for the film grown without buffer layer. The transition from hydrophobicity to hydrophilicity under UV irradiation occurs within 10 min. for the buffer layered films whereas it is almost 30 min. for the film grown without buffer layer. The enhanced photo induced hydrophilicity is shown to be surface energy driven.

Film Thickness and Friction Relationship in Grease Lubricated Rough Contacts

Directory of Open Access Journals (Sweden)

David Gonçalves

2017-08-01

Full Text Available The relationship between the film generation and the coefficient of friction in grease lubricated contacts was investigated. Ball-on-disc tests were performed under different operating conditions: entrainment speed, lubricant temperature and surface roughness. The tests were performed with fully formulated greases and their base oils. The greases were formulated with different thickener types and also different base oils natures and viscosities. Film thickness measurements were performed in ball-on-glass disc tests, and Stribeck curves were measured in ball-on-steel disc tests with discs of different roughness. The role of the thickener and the base oil nature/viscosity on the film thickness and coefficient of friction was addressed and the greases’ performance was compared based on their formulation.