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1
Abualigaledari, Sahar, Mehdi Salimi Jazi, and Fardad Azarmi. "Investigation on Fracture Toughness of Coating/Substrate Interface - Case Study: Thermally Sprayed Nickel Based Superalloy on Variety of Substrates." Materials Science Forum 900 (July 2017): 133–36. http://dx.doi.org/10.4028/www.scientific.net/msf.900.133.
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Nickel based superalloy materials have being extensively used in aerospace and other high tech industries. In the present work, the effect of different substrates on the mechanical properties of the coating-substrate interface has been studied. To this end, alloy 718, commercially known as Inconel 718, was deposited on alloy 718 and low carbon steel substrates using High Velocity Oxygen Fuel (HVOF) technique at the same condition. The bonding strength of the interfaces evaluated using Vickers indentation test on the coating-substrate interface. Hardness results were subjected to a valid empirical method to estimate the fracture toughness. Results illustrated that using the same material as coating and the substrate led to stronger interface bonding strength due to higher hardness, fracture toughness, and less crack propagation.
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Pal, Sunil K., Youngsuk Son, Theodorian Borca-Tasciuc, et al. "Thermal and electrical transport along MWCNT arrays grown on Inconel substrates." Journal of Materials Research 23, no. 8 (2008): 2099–105. http://dx.doi.org/10.1557/jmr.2008.0256.
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This work reports on thermal and electrical conductivities and interface resistances for transport along aligned multiwalled carbon nanotubes (CNT) films grown on a nickel superalloy (Inconel) substrate. The measured specific thermal resistance of the combined Inconel–CNT and indium–CNT interfaces is of the same order as reported for CNT and silicon or SiO2 interfaces but much higher than theoretical predictions considering perfect contact between the tubes and substrate. Imperfect mechanical contact with the substrate and a large contribution caused by indium–CNT interface are thought to be mainly responsible for the high interface resistances and the low effective values of thermal and electrical conductivities. However, reported results represent an incentive for further research on CNT synthesis on metallic substrates for thermal management applications and pave the way for much easier integration of carbon nanotubes in electronic applications.
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An, Bingbing. "Delamination of Stiff Films on Pressure Sensitive Ductile Substrates." International Journal of Applied Mechanics 11, no. 02 (2019): 1950014. http://dx.doi.org/10.1142/s1758825119500145.
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Stiff thin films supported by pressure sensitive ductile solids are an ubiquitous architecture appearing in a wide range of applications. The film rupture and delamination of films are important reliability issues of such an architecture. In this study, we investigate the synergistic effects of plastic deformation of substrates and fracture properties of film/substrate interface on the delamination of films. The focus of this study is on the interplay between the debonding of the interface and the plastic deformation of substrates. Finite deformation analyses are carried out for a stiff film deposited on a soft substrate with the substrate subjected to stretching. The fracture process of film/substrate interface is represented by a cohesive zone model, and the substrate is modeled as an elastic–plastic solid with pressure sensitive and plastically dilatant plastic flow. It is found that increasing the degree of pressure sensitivity of substrate can generate large plastic deformation, promoting crack tip blunting and thereby retarding delamination of film/substrate interface. Whereas, the increase in the degree of plastic dilatancy of substrate gives rise to the limited plastic deformation and leads to poor resistance to interface delamination. The strain hardening of substrate also affects the film/substrate debonding; the substrate with weakly post-yield strain hardening behavior contributes to enhanced resistance to interface delamination. It is further identified that the fracture properties of interface play an important role in activating plastic deformation of substrates. The film/substrate interface with high stiffness, large cohesive strength and high toughness enables the substrate to undergo significant plastic deformation, which suppresses the film/substrate delamination.
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Wang, Yun, Shihao Wang, Zhongping Que, et al. "Manipulating Nucleation Potency of Substrates by Interfacial Segregation: An Overview." Metals 12, no. 10 (2022): 1636. http://dx.doi.org/10.3390/met12101636.
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During solidification of metallic materials, heterogeneous nucleation occurs on substrates, either endogenous or exogenous. The potency of the substrates for nucleation is mainly dependent upon the atomic arrangements on the substrate surface, which are affected by the lattice misfit between the substrate and the nucleated solid, the surface roughness at atomic scale, and the chemical interaction between the substrates and the melt. Extensive examinations on metal/substrate (M/S) interfaces at atomic scale by the state-of-the-art aberration (Cs) corrected STEM and associated EDS and EELS have shown that alloying elements in liquid melts tend to segregate at the interfaces, leading to the formation of various 2-dimensional compounds (2DCs) or 2-dimensional solutions (2DSs), depending upon segregation behavior of the elements. For instance, Al3Ti 2DC and Ti2Zr 2DC at the Al/TiB2 interface, Y2O3 2DC at the Mg/MgO interface, and a Si-rich 2DS layer at Al-Si/TiB2 interface have been identified. Such interfacial segregations significantly affect nucleation potency of the substrates, resulting in either promoting or impeding the heterogeneous nucleation process during solidification. In this paper, we present an overview of the current studies of interfacial segregation behavior, the structure and chemistry of interfaces, and their impacts on the subsequent heterogeneous nucleation and grain initiation processes. Our focus is on the advances made in the understanding of the mechanisms for nucleation and grain refinement. It is demonstrated that it is feasible to manipulate heterogeneous nucleation by modifying nucleation potency of a substrate through deliberate interfacial segregation of desirable elements, achieving effective control of the grain structure of cast metallic materials.
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Li, Hui Qing, Cheng Ming Li, Guang Chao Chen, Fan Xiu Lu, and Yu Mei Tong. "Analysis of Interface between Free-Standing Diamond Films and Mo Substrates." Materials Science Forum 475-479 (January 2005): 3615–18. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.3615.
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Interfaces between Mo substrate and free-standing diamond films prepared by DC arc plasma jet operated at gas recycling mode were investigated, including for the first time used and multi-time used substrate. The morphology, phase composition and bonding state of elements in the interface between substrates and diamond films were examined by optical microscopy, XRD and XPS. The profiles of carbon concentration of Mo substrates were measured by GDOES. It showed that Mo2C and MoC were formed on the first time used Mo substrate, and MoC was found on diamond films nucleation side after detachment. It suggested that MoC was peeled off from Mo substrate. The stable Mo2C on Mo substrate was formed after multi-time use of Mo substrate. However, MoC has not been found on it. The thickness of carburizing layer on the first time used Mo substrate is up to 30µm, and the carburizing layer on the multi-time used substrate is much thicker than that on the first used. The amorphous carbon in the surface of the substrate and nucleation side of diamond films was found by XPS, including for the first time used and multi-time used substrate.
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Prasad, Beesabathina D., L. Salamanca-Riba, S. N. Mao, X. X. Xi, T. Venkatesan, and X. D. Wu. "Effect of substrate materials on laser deposited Nd1.85Ce0.15CuO4−y films." Journal of Materials Research 9, no. 6 (1994): 1376–83. http://dx.doi.org/10.1557/jmr.1994.1376.
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The growth morphology and interface structure of Nd1.85Ce0.15CuO4−y (NCCO) films grown by pulsed laser deposition on two different types of substrates, “perovskite” LaAlO3 (LAO) and SrTiO3 (STO) and “fluorite” Y2O3-stabilized ZrO2 (YSZ), were studied using cross-sectional electron microscopy. Structurally, the NCCO films are different when grown on the two types of substrates in three aspects: (i) epitaxy, (ii) substrate-film intermixing, and (iii) substrate-film interface roughness. In general, films deposited on “fluorite” substrates showed better superconducting properties than the films grown on “perovskite” substrates, especially for thinner films. Lattice mismatch considerations are not sufficient to explain the observed differences since films grown on the YSZ substrate showed sharp substrate-film interface in spite of their large lattice misfit. The atomic arrangements at the interface were analyzed in terms of electrostatic energy (charge balance) and matching of the oxygen sublattices in order to account for the experimental results.
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Kis-Varga, Miklos, G. A. Langer, A. Csik, Z. Erdélyi, and Dezső L. Beke. "Effect of Substrate Temperature on the Different Diffuseness of Subsequent Interfaces in Binary Multilayers." Defect and Diffusion Forum 277 (April 2008): 27–31. http://dx.doi.org/10.4028/www.scientific.net/ddf.277.27.
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Epitaxial, coherent Mo/V multilayers were deposited by magnetron sputtering on (001) oriented MgO substrates at 873K (sample MoV-T), 923K (sample MoV-U) and 973K (sample MoV-V), respectively. In order to estimate the concentration profiles in our multilayers, a superlattice refinement modelling procedure has been used on high-angle XRD symmetric scans. The Mo/V interfaces were always sharper than V/Mo ones (in this notation the order of element reflects the sequence of deposition: e.g. the Mo/V interface was formed by the deposition of the V on the Mo surface). Furthermore the interface diffuseness was only slightly different at the lowest substrate temperature, but the difference increased with increasing temperature and an abrupt concentration jump could be observed at the Mo/V interface in the sample, sputtered at the 973 K. This indicates that during deposition the interfacial mixing by impact exchange events is important and thermally activated processes (surface diffusion and/or jumps driven by segregation) are less effective. With increasing substrate temperature the thickness of the V/Mo interfaces were unchanged while the Mo/V interface became shaper and sharper i.e. thermally activated jumps were more active during deposition of V atoms. Thus in forming Mo/V interfaces the segregation tendency of V to the Mo surface results in enhanced exchanges between V atoms (buried in the near surface layers of the Mo substrate) and surface Mo atoms, leading to more sharper interface with increasing temperature. On the other hand during the formation of the V/Mo interfaces the chemical thickness of the interface, provided again by impact exchanges, was practically unchanged.
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ZHAO, HONG-PING, YECHENG WANG, BING-WEI LI, and XI-QIAO FENG. "IMPROVEMENT OF THE PEELING STRENGTH OF THIN FILMS BY A BIOINSPIRED HIERARCHICAL INTERFACE." International Journal of Applied Mechanics 05, no. 02 (2013): 1350012. http://dx.doi.org/10.1142/s1758825113500129.
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The peeling behavior of a thin film bonded to a substrate is investigated by using the cohesive interface model. We compare the peeling processes of film/substrate interfaces with three different geometric shapes, including a flat interface, a curved interface of sinusoidal shape, and a wavy interface with two-level sinusoidal hierarchy. The effect of the peeling angle on the maximal peeling strength is also examined. It is demonstrated that the peeling strength can be significantly improved by introducing a hierarchical wavy morphology at the film/substrate interface. This study may be helpful for the design of film/substrate systems with enhanced mechanical properties.
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Song, Zhuguo, and Hui Li. "Plasma Spraying with Wire Feeding: A Facile Route to Enhance the Coating/Substrate Interfacial Metallurgical Bonding." Coatings 12, no. 5 (2022): 615. http://dx.doi.org/10.3390/coatings12050615.
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Thermal spray coatings are widely used in many applications, and the adhesion effect at the coating/substrate interface plays an important role during the service life. The thermal spraying coating and substrate is primarily combined by a mechanical seizure effect. In this work, a strategy to generate interfacial metallurgical bonding is proposed. Plasma spraying with wire feeding was adopted to increase the size of sprayed particles, and metallurgical bonding was clearly formed between deposited particles and the substrate (304 stainless-steel and 7075 aluminum alloy). Interface reaction can be found at both NiAl/7075 and NiAl/304 interfaces. Typical Al-Al3Ni eutectic phase with higher microhardness was formed at NiAl/7075 interface. The adhesive strength of the coatings was significantly improved to 82.67 ± 3.96 MPa and 64.45 ± 2.84 MPa, respectively, for NiAl coating on 304 and 7075 substrates through tensile adhesion tests (TAT) without surface roughening pretreatment. This technique shows a promising aspect of the application of thermal spray coatings.
10
Yamagiwa, K., K. Matsumoto, and I. Hirabayashi. "Solid-phase epitaxial growth of oxide buffer materials for Rba2Cu3O7−y(R: rare earth and Y) superconductor." Journal of Materials Research 15, no. 11 (2000): 2547–57. http://dx.doi.org/10.1557/jmr.2000.0365.
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We prepared various oxide buffer films on single-crystalline oxide substrates using chemical solution deposition to investigate general interfacial problems of buffer layers for coated conductors, such as epitaxial relationships between buffer material and the substrate. We found that (i) interfaces between the films and the substrates having the same crystal structure were compatible, even in a range of misfit value up to 7%, showing in-plane alignment; however (ii) interfaces between the films and substrates of other combinations of interface structures, with and without occupying tetragonal sites, narrow the range of the epitaxial growth. The former results (i) can be explained by the arrangement of oxygen ions, but for the latter cases (ii), cation arrangement is also important in forming a compatible interface as well as an anion arrangement. The general tendency is largely explained by the ionic arrangement at the interface. The interface structure becomes unstable by the electrostatic repulsive force since the distance between cations at the interface becomes shorter than that in each original crystal structure.
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LIANG, JIACHANG, LIPING ZHANG, ZHIPING WANG, et al. "PREPARATION OF GRADATED NANO-TRANSIENT LAYER AT INTERFACE BETWEEN DEPOSITED FILM AND SUBSTRATE BY HIGH-INTENSITY PULSED ION BEAM IRRADIATION." Surface Review and Letters 17, no. 05n06 (2010): 463–68. http://dx.doi.org/10.1142/s0218625x10014296.
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We prepared gradated nano-transient layers at different interfaces between deposited film and substrates by high-intensity pulsed ion beam (HIPIB) irradiation. The deposited film was ( Al–Si ) alloy and substrates were Ni and Ti , respectively. The gradated nano-transient layers at different interfaces were measured by Rutherford backscattering, its spectra were solved by SIMNRA code and then the microstructures of the gradated nano-transient layers at the interfaces of these two irradiated samples were obtained. The experimental results were analyzed by STEIPIB code. The formation of the gradated distribution of element contents in nano-transient layer at the interface can eliminate the abrupt changes of thermal and elastic characteristics at the interface. And, it can greatly reduce the mismatch of thermal expansion coefficients and Young's modulus at the interface between deposited film and substrate. Thus, after the formation of the gradated nano-transient layer, the adhesion at the interface between different materials can be enhanced and the level of thermal stresses can also be reduced in the case of thermal loading.
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Guo, Y. X., and Y. W. Zhao. "Effect of Interlayer on the Elastic-Plastic Deformation of Coating Systems." Journal of Mechanics 35, no. 3 (2019): 373–80. http://dx.doi.org/10.1017/jmech.2018.46.
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ABSTRACTThe finite element method (FEM) was used to study the elastic-plastic contact in the coating systems with interlayer. The results reveal that with the increase of interlayer thickness, the maximum shear stress of coating/interlayer and interlayer/substrate interfaces decreases. Moreover, the sharply changed shear stress between the interfaces of coating/interlayer and interlayer/substrate decreases too. There is no further decrease when interlayer thickness increase to 0.04 mm and above. With the increasing of interlayer elastic modulus, the shear stress of coating/interlayer interface decreases while the shear stress of interlayer/substrate interface increases. Meanwhile, the higher elastic modulus leads to the intensive tensile stress concentration on the interface of coating/interlayer. Hence, the interlayer with appropriate elastic modulus not only reduces the shear stress of coating/interlayer and interlayer/substrate interfaces but also decreases the tensile stress of coating/interlayer interface. The mechanical properties of coating systems were investigated with different interlayer yield strength. The effective hardness and elastic modulus increase with the increase of interlayer yield strength, which is good to protect the substrate from the deformation. In addition, higher indentation load can lead to the decrease of effective hardness and elastic modulus.
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Sasaki, Takashi, Masaaki Nakagiri, and Satoshi Irie. "Interfacial Effects on the Spherulitic Morphology of Isotactic Polystyrene Thin Films on Liquid Substrates." Advances in Materials Science and Engineering 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/4849798.
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The influence of interfaces on the morphology of flat spherulites of isotactic polystyrene (iPS) grown in thin films on liquid substrates was investigated. Amorphous iPS thin films spin-cast from a solution were annealed for cold crystallization on glycerol and silicone oil (nonsolvents for iPS). The number density of grown spherulites was revealed to be higher on the glycerol substrate than on the silicone oil substrate. This implies that the primary nucleation rate of crystallization is greater at the iPS/glycerol interface than at the iPS/silicone oil interface. The results may be consistent with the previous findings that concern the molecular interaction between atactic polystyrene and nonsolvents at the interface. In some cases, holes were formed in the thin films during the cold crystallization due to dewetting, which also significantly affect the spherulite morphology via, for example, transcrystallization.
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Goto, Toichiro, Nahoko Kasai, Rick Lu, Roxana Filip, and Koji Sumitomo. "Scanning Electron Microscopy Observation of Interface Between Single Neurons and Conductive Surfaces." Journal of Nanoscience and Nanotechnology 16, no. 4 (2016): 3383–87. http://dx.doi.org/10.1166/jnn.2016.12311.
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Interfaces between single neurons and conductive substrates were investigated using focused ion beam (FIB) milling and subsequent scanning electron microscopy (SEM) observation. The interfaces play an important role in controlling neuronal growth when we fabricate neuron-nanostructure integrated devices. Cross sectional images of cultivated neurons obtained with an FIB/SEM dual system show the clear affinity of the neurons for the substrates. Very few neurons attached themselves to indium tin oxide (ITO) and this repulsion yielded a wide interspace at the neuron-ITO interface. A neuron-gold interface exhibited partial adhesion. On the other hand, a neuron-titanium interface showed good adhesion and small interspaces were observed. These results are consistent with an assessment made using fluorescence microscopy. We expect the much higher spatial resolution of SEM images to provide us with more detailed information. Our study shows that the interface between a single neuron and a substrate offers useful information as regards improving surface properties and establishing neuron-nanostructure integrated devices.
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Chien, F. R., S. R. Nutt, J. M. Carulli, N. Buchan, C. P. Beetz та W. S. Yoo. "Heteroepitaxial growth of β'-SiC films on TiC substrates: Interface structures and defects". Journal of Materials Research 9, № 8 (1994): 2086–95. http://dx.doi.org/10.1557/jmr.1994.2086.
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Thin epitaxial films of β-SiC were grown by CVD on (100), (111), and (112) TiC substrates. TEM observations of the resulting interfaces revealed that island nucleation prevailed in the early stages of deposition for all three substrate orientations. Films grown on (111) and (112) TiC were monocrystalline, while SiC films deposited on (100) substrates were polycrystalline and not epitaxial, a phenomenon attributed to the poor match of atomic positions in SiC and TiC on their respective (100) planes. The (111) interface was abrupt and atomically flat, while the (112) interface exhibited {111} facets and steps. Simulated images of the stable (111) interface were calculated based on several possible atomic configurations, and the atomic structure of the interface was deduced from comparisons between the simulated images and phase-contrast TEM images.
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Okuno, Eiichi, Takeshi Endo, Toshio Sakakibara, Shoichi Onda, Makoto Itoh, and Tsuyoshi Uda. "Ab Initio Calculations of SiO2/SiC Interfaces and High Channel Mobility MOSFET with (11-20) Face." Materials Science Forum 615-617 (March 2009): 793–96. http://dx.doi.org/10.4028/www.scientific.net/msf.615-617.793.
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Ab initio calculations were carried out to study the origin of the trap at the SiO2/SiC (MOS: Metal-Oxide-Semiconductor) interface with the three different faces of the substrate, (0001), (000-1), and (11-20). In a previous report we experimentally discovered that the (11-20) face is suitable for high channel mobility. The calculation in this report showed that the MOS interface achieved the intermediate states due to distortion and thus acted like an interface trap. The interface trap density of the MOS interface on the (11-20) face substrate was smaller than those on the other faces. The interface trap densities were 2.14, 3.36, and 1.40 in units of 1015 cm-2 for the above listed substrate orientations, respectively. For clarity, the channel mobility was compared experimentally to reveal that it realized a larger value for the (11-20) substrate than the other two faces. From our results, we concluded that (11-20) face substrate was more suitable for high power device applications than the (0001) face or (000-1) face substrates.
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Xu, J., M. J. Cox, and M. J. Kim. "Chemically Clean Planar Interface Synthesis: Substrate Surface and Interface Cross Section Microscopy." Microscopy and Microanalysis 3, S2 (1997): 635–36. http://dx.doi.org/10.1017/s1431927600010060.
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An ultra high vacuum (UHV) planar interface unit has been constructed to study the effect of interface/boundary structure and chemistry on properties. We report here initial observations of substrate morphology and chemistry prior to bonding and resulting interface morphology obtained using austenitic stainless steel.To synthesize chemically clean planar interfaces by diffusion bonding, the substrate must be macroscopically and microscopically flat and chemically clean. Macro-flatness, necessary for bonding to occur over large areas, was ensured by conventional mechanical polishing and lapping. Substrate surfaces were cleaned by a broad (3cm) 500 eV ion beam (Ar or Xe) at 15° incidence. The resulting changes in substrate near-atomic-scale roughness and chemistry were analyzed using Auger spectroscopy (AES) and Atomic Force Microscopy (AFM). Before ion beam cleaning, the sub-strates exhibited high oxygen and carbon contamination (Fig la). Both Xe and Ar ion cleaning reduced these values; the result for 5 minutes Ar cleaning is shown in Fig lb.
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Jiang, Jiechao, J. He, Efstathios I. Meletis, Jian Liu, Z. Yuan, and Chong Lin Chen. "Two-Dimensional Modulated Interfacial Structures of Highly Epitaxial Ferromagnetic (La,Ca)MnO3 and Ferroelectric (Pb,Sr)TiO3 Thin Films on (001) MgO." Journal of Nano Research 3 (October 2008): 59–66. http://dx.doi.org/10.4028/www.scientific.net/jnanor.3.59.
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Two-dimensional in-plane interface structures of highly epitaxial perovskite (La,Ca)MnO3 (LCMO) and (Pb,Sr)TiO3 (PSTO) thin films on salt-rock type MgO substrate were studied using Transmission Electron Microscopy (TEM). Cross-section TEM studies revealed that both LCMO and PSTO films are good single crystal quality and have atomic sharp interface with respect to the MgO substrate with -6.4% and -6.2% lattice mismatch, respectively. Electron Diffraction Patterns (EDPs) of plan-view LCMO/MgO and PSTO/MgO interfaces exhibit double diffraction spots. An analytical approach was employed using double diffraction to study the two-dimensional in-plane interfaces of perovskite structure films on the salt-rock type substrate. The lattice mismatch near the interface regions was determined using EDPs of the plan-view interfaces and found to be -8.0% for LCMO/MgO and -7.14% for PSTO. Both latter values are larger than those obtained using cross-section TEM. Studies of the sharpness of double diffraction spots and plan-view high resolution (HR) TEM brought a conclusion that the PSTO film is well commensurate with the MgO substrate over large areas, whereas LCMO film is only locally commensurate with the substrate. These studies provide additional evidence to our previous observations that plan-view TEM of the interface is able to provide critical and valuable information that is lacking from the cross-section TEM analysis.
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Josell, D., J. E. Bonevich, I. Shao, and R. C. Cammarata. "Measuring the interface stress: Silver/nickel interfaces." Journal of Materials Research 14, no. 11 (1999): 4358–65. http://dx.doi.org/10.1557/jmr.1999.0590.
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Interface stress is a surface thermodynamics quantity associated with the reversible work of elastically straining an internal solid interface. In a multilayered thin film, the combined effect of the interface stress of each interface results in an in-plane biaxial volume stress acting within the layers of the film that is inversely proportional to the bilayer thickness. We calculated the interface stress of an interface between {111} textured Ag and Ni on the basis of direct measurements of the dependence of the in-plane elastic strains on the bilayer thickness. The strains were obtained using transmission x-ray diffraction. Unlike previous studies of this type, we used freestanding films so that there was no need to correct for intrinsic stresses resulting from forces applied by the substrate that can lead to large uncertainties of the calculated interface stress value. Based on the lattice parameters of the bulk, pure elements, an interface stress of −2.02 ± 0.26 N/m was calculated using the x-ray diffraction results from films with bilayer thicknesses greater than 5 nm. This value is somewhat smaller than previous measurements obtained from as-deposited films supported by substrates. For smaller bilayer thicknesses the apparent interface stress becomes smaller in magnitude, possibly due to a loss of layering in the specimens.
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Styler, S. A., M. E. Loiseaux, and D. J. Donaldson. "Substrate effects in the photoenhanced ozonation of pyrene." Atmospheric Chemistry and Physics Discussions 10, no. 11 (2010): 27825–52. http://dx.doi.org/10.5194/acpd-10-27825-2010.
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Abstract. We report the effects of actinic illumination on the heterogeneous ozonation kinetics of solid pyrene films and pyrene adsorbed at air-octanol and air-aqueous interfaces. Upon illumination, the ozonation of solid pyrene films and pyrene at the air-aqueous interface proceeds more quickly than in darkness; no such enhancement is observed for pyrene at the air-octanol interface. Under dark conditions, the reaction of pyrene at all three interfaces proceeds via a Langmuir-Hinshelwood-type surface mechanism. In the presence of light, Langmuir-Hinshelwood kinetics are observed for solid pyrene films but a linear dependence upon gas-phase ozone concentration is observed at the air-aqueous interface. We interpret these results as evidence of the importance of charge-transfer pathways for the ozonation of excited-state pyrene. The dramatically different behaviour of pyrene at the surface of these three simple reaction environments highlights the difficulties inherent in representing complex reactive surfaces in the laboratory, and suggests caution in extrapolating laboratory results to environmental surfaces.
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Styler, S. A., M. E. Loiseaux, and D. J. Donaldson. "Substrate effects in the photoenhanced ozonation of pyrene." Atmospheric Chemistry and Physics 11, no. 3 (2011): 1243–53. http://dx.doi.org/10.5194/acp-11-1243-2011.
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Abstract. We report the effects of actinic illumination on the heterogeneous ozonation kinetics of solid pyrene films and pyrene adsorbed at air-octanol and air-aqueous interfaces. Upon illumination, the ozonation of solid pyrene films and pyrene at the air-aqueous interface proceeds more quickly than in darkness; no such enhancement is observed for pyrene at the air-octanol interface. Under dark conditions, the reaction of pyrene at all three interfaces proceeds via a Langmuir-Hinshelwood-type surface mechanism. In the presence of light, Langmuir-Hinshelwood kinetics are observed for solid pyrene films but a linear dependence upon gas-phase ozone concentration is observed at the air-aqueous interface. We interpret these results as evidence of the importance of charge-transfer pathways for the ozonation of excited-state pyrene. The dramatically different behaviour of pyrene at the surface of these three simple reaction environments highlights the difficulties inherent in representing complex reactive surfaces in the laboratory, and suggests caution in extrapolating laboratory results to environmental surfaces.
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Mattogno, Giulia, Guido Righini, Giampiero Montesperelli, and Enrico Traversa. "X-ray photoelectron spectroscopy investigation of MgAl2O4 thin films for humidity sensors." Journal of Materials Research 9, no. 6 (1994): 1426–33. http://dx.doi.org/10.1557/jmr.1994.1426.
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MgAl2O4 thin films, to be studied as active elements for humidity sensors, were deposited on Si/SiO2 substrates by radio-frequency sputtering. This paper discusses the x-ray photoelectron spectroscopy (XPS) investigation of these films. XPS demonstrated that the thin films had a stoichiometry close to that of MgAl2O4. The evaluation of the modified Auger parameter α' for Al gave structural information about the order of the crystalline structure of the thin films. The combination of Ar+ ion etching and XPS analysis showed the simultaneous presence of Mg, Al, and Si at the film-substrate interface. The thicknesses of the interfaces were calculated between 7 and 10 nm. The analysis of the binding energy (b.e.) values of the XPS peaks at different etching depths showed that O 1s and Si 2p b.e. values were characteristic of a silicate at the interface, whereas in the substrate they were typical of silica. This suggests a chemical interaction took place between film and substrate with the formation of a silicate layer at the interface, which may be the cause of the good adhesion of MgAl2O4 films to silica, as observed by peel tests with Scotch tape.
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Goyal, D., and A. H. King. "TEM observations of the mechanism of delamination of chromium films from silicon substrates." Journal of Materials Research 7, no. 2 (1992): 359–66. http://dx.doi.org/10.1557/jmr.1992.0359.
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We have observed the complete delamination of polycrystalline chromium films from single crystal silicon substrates during deposition due to the formation of high internal stresses. These intrinsic stresses can give rise to interfacial defects which assist in the separation of the film from the substrate. Stresses in the film are balanced by stresses in the substrate, which cause mechanical failure in the substrate near the interface. Extensive arrays of dislocations and cracking of the substrate have been observed. We find that the delamination of the films from the substrate is initiated by the formation of damage in the substrate, rather than to the film or the interface.
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He, Xiangjun, Si-Ze Yang, Kun Tao, and Yudian Fan. "Investigation of the interface reactions of Ti thin films with AlN substrate." Journal of Materials Research 12, no. 3 (1997): 846–51. http://dx.doi.org/10.1557/jmr.1997.0123.
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Pure bulk AlN substrates were prepared by hot-pressing to eliminate the influence of an aid-sintering substance on the interface reactions. AlN thin films were deposited on Si(111) substrates to decrease the influence of charging on the analysis of metal/AlN interfaces with x-ray photoelectron spectroscopy (XPS). Thin films of titanium were deposited on bulk AlN substrates by e-gun evaporation and ion beam assisted deposition (IBAD) and deposited on AlN films in situ by e-gun evaporation. Solid-state reaction products and reaction mechanism of the Ti/AlN system annealed at various temperatures and under IBAD were investigated by XPS, transmission electron microscopy (TEM), x-ray diffraction (XRD), and Rutherford backscattering spectrometry (RBS). Ti reacted with AlN to form a laminated structure in the temperature range of 600 °C to 800 °C. The TiAl3 phase was formed adjacent to the AlN substrate, TiN, and Ti4N3−x as well as Ti2N were formed above the TiAl3 layer at the interface. Argon ion bombardment during Ti evaporation promoted the interface reactions. No reaction products were detected for the sample as-deposited by evaporation. However, XPS depth profile of the Ti/AlN/Si sample showed that Ti–N binding existed at the interface between the AlN thin films and the Ti thin films.
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Terabe, K., A. Gruverman, Y. Matsui, N. Iyi, and K. Kitamura. "Transmission electron microscopy observation and optical property of sol-gel derived LiNbO3 films." Journal of Materials Research 11, no. 12 (1996): 3152–57. http://dx.doi.org/10.1557/jmr.1996.0400.
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Crystallization behavior, defects, and interface structures of sol-gel derived LiNbO3 films on three kinds of substrates were examined. The nucleation was found to occur epitaxially at the interface between the film and the substrate. The continuous film is formed by coalescence of the island-like crystallites. When sapphire substrate is used, which has large lattice mismatch with the LiNbO3, the resulting film contains a large amount of micropores, twin structures, and misfit dislocations. On the other hand, while LiTaO3 and 5% MgO-doped LiNbO3 substrates with smaller mismatch are used as substrates, the films show no evidence of the formation of dislocations and twins. The film on 5% MgO-doped LiNbO3 substrate shows better optical waveguiding property.
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Hubmann, Andreas, Dominik Dietz, Joachim Brötz, and Andreas Klein. "Interface Behaviour and Work Function Modification of Self-Assembled Monolayers on Sn-Doped In2O3." Surfaces 2, no. 2 (2019): 241–56. http://dx.doi.org/10.3390/surfaces2020019.
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The modification of the work function of Sn-doped In2O3 (ITO) by vacuum adsorption of 4-(Dimethylamino)benzoic acid (4-DMABA) has been studied using in situ photoelectron spectroscopy. Adsorption of 4-DMABA is self-limited with an approximate thickness of a single monolayer. The lowest work function obtained is 2.82 ± 0.1 eV, enabling electron injection into many organic materials. In order to identify a potential influence of the ITO substrate surface on the final work function, different ITO surface orientations and treatments have been applied. Despite the expected differences in substrate work function and chemical bonding of 4-DMABA to the substrate, no influence of substrate surface orientation is identified. The resulting work function of ITO/4-DMABA substrates can be described by a constant ionization potential of the adsorbed 4-DMABA of 5.00 ± 0.08 eV, a constant band alignment between ITO and 4-DMABA and a varying Fermi energy in the ITO substrate. This corresponds to the behaviour of a conventional semiconductor heterostructure and deviates from the vacuum level alignment of interfaces between organic compounds. The difference is likely related to a stronger chemical bonding at the ITO/4-DMABA interface compared to the van der Waals bonding at interfaces between organic compounds.
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Matsumae, Takashi, Hitoshi Umezawa, Yuichi Kurashima, and Hideki Takagi. "(Invited, Digital Presentation) Low-Temperature Direct Bonding of Wide-Bandgap Semiconductor Substrates." ECS Meeting Abstracts MA2023-01, no. 32 (2023): 1830. http://dx.doi.org/10.1149/ma2023-01321830mtgabs.
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Low-temperature direct bonding technique of semiconductor substrates has been developed to integrate dissimilar materials (e.g. Si, Ge, III-V) regardless of lattice and thermal expansion mismatches. Among the direct bonding techniques, a hydrophilic bonding method, which initiates a dehydration reaction between OH-terminated substrates, is commonly used because wafer-scale bonding can be fabricated under atmospheric conditions. Recently, our research group achieved direct bonding of wide-gap materials, including SiC, GaN, β-Ga2O3, and diamond substrates, by using this bonding method. The hydrophilic bonding of Si wafers has been practically applied for the fabrication of silicon-on-insulator substrates. In the bonding process, the Si substrates are typically irradiated with reactive ion etching using oxygen plasma, which efficiently generates OH groups on the surface. By contacting the substrates under atmospheric conditions, the activated surfaces can adhere to each other by hydrogen bonds across the OH groups. The annealing at ~200 °C causes the dehydration reaction and forms atomic bonds between the substrates, as shown in the following equation. Si-OH + HO-Si → Si-O-Si +H2O The bonding process generates a sub-10-nm-thick SiOx layer at the bonding interface, which limits thermal and electrical conductance between the bonding substrates. Our research group demonstrated that the diamond substrates can be bonded with other semiconductor substrates (e.g. Si, InP, β-Ga2O3) by the hydrophilic bonding method. The pre-bonding treatment using oxygen plasma is not suitable for the diamond surface because it is easily etched by the strong oxidizing treatment. Meanwhile, the mild oxidizing treatment using H2SO4/H2O2 (i.e. piranha solution) and NH3/H2O2 (i.e. SC1) mixtures enables OH termination of the diamond substrate without a significant increase in the surface roughness. Figure A shows the photograph of the diamond substrate bonded on the Si substrate. At the Si/diamond and InP/diamond bonding interfaces, ~3-nm-thick SiOx and InPOx layers were observed by an electron microscope, respectively, as displayed in Figure B. These oxide layers were formed by the oxidizing treatment at the pre-bonding step. However, when β-Ga2O3 and diamond substrates were bonded, such an oxide intermediate layer was not observed at the bonding interface. This is because diamond never develops the oxide layer and β-Ga2O3 is an oxide material. As shown in Figure C, we achieved the direct bonding of monocrystalline β-Ga2O3 and diamond substrates with an amorphous intermediate layer thinner than 1 nm. As the intermediate layer was atomically thin, efficient electrical and thermal conductance across β-Ga2O3/diamond substrates was possible, as plotted in Figure D. Qiushi Kang et al. demonstrated that the hydrophilic bonding of the SiC substrate is possible by using oxygen plasma. This treatment develops the ~4-nm-thick SiOx layer on the SiC substrate, which possibly became a thermal and electrical barrier at the bonding interface. However, our research group revealed that the SiC substrate dipped into HF acid can form direct bonding with an atomically thin intermediate layer. It is known that the SiC surface is OH terminated after the removal of the native oxide layer by HF acid, unlike the Si substrate. We revealed that the HF-dipped SiC substrate can form direct bonding with the O2-plasma-activated β-Ga2O3 substrate through an intermediate layer as thin as 1 nm. as displayed in Figure E. About the GaN substrate, we have demonstrated that hydrophilic bonding with the Si substrate is possible using oxygen and nitrogen plasma activations. In addition, the GaN substrate dipped into H2SO4/H2O2 and NH3/H2O2 mixtures can also form direct bonding. The thickness of the GaOx layer at the GaN/Si bonding interface was approximately 1 nm. We believe the low-temperature direct bonding technique will contribute to future wide-bandgap semiconductor devices because it is possible to achieve efficient electrical and thermal conduction across dissimilar materials. Figure 1
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Wang, Xi Shu, Xi Qiao Feng, and Xing Wu Guo. "Failure Behavior of Anodized Coating-Magnesium Alloy Substrate Structures." Key Engineering Materials 261-263 (April 2004): 363–68. http://dx.doi.org/10.4028/www.scientific.net/kem.261-263.363.
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This work focuses on the damage mechanisms and the resulting failure behavior of structures made of anodized coatings on magnesium alloy substrates. The failure of anodized coatings of about 30µm thickness on AZ91D substrates was investigated under three-points bending loading with online scanning electron microscope (SEM) observations. The obtained SEM images show that void nucleation and crack initiation occurs mainly at sites near the coating-substrate interface, and the evolutionary microcracking damage diffuses from the interface to the coating surface and also to the bulk substrate with the increasing in loading.
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Xie, Kuo Jun, Chang Shun Jiang, Lin Zhu, and Hai Feng Xu. "Thermal Stress Analysis of MCM Package Using Diamond Material." Key Engineering Materials 353-358 (September 2007): 2904–7. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.2904.
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With the increasing of packaging integration the power and the quantity of heat of integrate circuit will increase, it will bring more and more temperature distributions and problems about thermal stresses in package. In this paper a finite element thermal stress model of substrate-adhesive-chip is established, thermal stress distribution of substrate-chip interfaces and the affects of geometrical structure on thermal stresses are analyzed by finite element method, especially discuss interfacial thermal stresses distributions on chip-adhesive interface and adhesinve-substrate interface.
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Wu, X. S., and J. X. Xu. "Effect of pre-annealing of Mo foil substrate on CZTSSe thin films and Mo(S,Se)2 interface layer." Chalcogenide Letters 19, no. 9 (2022): 599–609. http://dx.doi.org/10.15251/cl.2022.199.599.
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Cu2ZnSn(S,Se)4 (CZTSSe) thin film deposited on flexible Mo foil substrate has advantage of high mass specific power and good ductility. However, a thick Mo(S,Se)2 interface layer is easily to be formed between CZTSSe and Mo foil substrate. The ohmic contact property of CZTSSe/Mo is deteriorated by the formation of Mo(S,Se)2. In this work, the Mo foil substrate was pre-annealed to inhibit the growth of Mo(S,Se)2 interface layer. CZTSSe thin films were prepared on the pre-annealed Mo foil substrate by sol-gel and selenization methods. The pre-annealing treatment of Mo foil substrate leads to the oxidation of Mo. During the high temperature selenization process, the MoOx acts as a buffer layer to suppress the formation of the Mo(S,Se)2 interface layer. With the increase of the pre-annealing temperature of the Mo foil substrate, the thickness of the Mo(S,Se)2 interface layer decreases, and the resistance of CZTSSe/Mo(S,Se)2/Mo structure decreases. The ohmic contact properties of CZTSSe/Mo can be improved by the pre-annealing treatment of metal Mo foil substrates.
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Long, Yangyang, Jens Twiefel, Joscha Roth, and Jörg Wallaschek. "Real-Time Observation of Interface Relative Motion during Ultrasonic Wedge-Wedge Bonding Process." International Symposium on Microelectronics 2015, no. 1 (2015): 000419–24. http://dx.doi.org/10.4071/isom-2015-wp35.
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As a predominant interconnection technique in microelectronic industry, ultrasonic wire bonding has been investigated for decades ever since its invention. Due to the extremely short process time, high operating frequency and ultrathin interfaces, many mechanisms are still unknown. One focus point of the research is the motion behaviors at the two interfaces – interface between wire & substrate (wire/substrate) and interface between wire & bonding tool (wire/tool). In this project, the motion behaviors at the two interfaces were observed by a high speed camera combined with an optical magnification system. The relative motion at the wire/substrate interface was recorded at maximum a frame rate of 350,515 fps which is approximately six times higher than the bonding frequency. The relative motion is caused by the vibration induced reciprocal motion and the plastic deformation induced material flow. The wire/tool interface was observed at lower frame rates due to the window size confinement. Through the observations, a relative motion was captured for the first time. This discovery indicates that the process parameters must be carefully controlled so that cratering as well as other damaging problems can be avoided.
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Liang, Lihong, Linfeng Chen, Luobing Wu, and Huifeng Tan. "Interface Strength, Damage and Fracture between Ceramic Films and Metallic Substrates." Materials 14, no. 2 (2021): 353. http://dx.doi.org/10.3390/ma14020353.
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Interface strength, damage and fracture properties between ceramic films and metallic substrates affect the service reliability of related parts. The films’ thickness, grain size and residual stress affect the interface properties and fracture behavior, thus related studies attract great attention. In this paper, the interface damage evolution and fracture behavior between ceramic films and metallic substrates were simulated by developing a three dimensional finite element model of alumina films on Ni substrates with cohesive elements in the interfaces. The interface fracture energy as a key parameter in the simulation was firstly determined based on its thermodynamic definition. The simulation results show the Mises stress distribution and damage evolution of the film/substrate structures during uniaxial tensile loading. Specially, when grain size of the films is in nanoscale, the interface strength increases obviously, agreeing with the previous experimental results. The effects of residual stress on interface properties was further simulated. The interface strength was found to decrease with increasing radial residual force and the axial residual pressure increases the interface strength. When the thickness of the films increases, the interface strength keeps a constant but the speed of interface damage becomes faster, that is, the thicker films show catastrophic fracture. The underlying mechanism of damage speed was analyzed. Understanding these size effects and the effects of residual stress is helpful to guide the design of related parts.
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Wu, J. S., C. L. Jia, K. Urban, J. H. Hao, and X. X. Xi. "Misfit relaxation in SrTiO3/SrRuO3 bilayer films on LaA1O3(100) substrates." Microscopy and Microanalysis 7, S2 (2001): 1222–23. http://dx.doi.org/10.1017/s1431927600032189.
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Besides perfect dislocations, partial dislocations were proposed as effective means for misfit relaxation in the heretostructure system [1]. The microstructure of SrRuO3 films on SrTiO3 and LaA1O3 substrates have been studied. While misfit dislocations could be hardly found at the SrTiO3/SrRuO3 interface [2], high density of defects was observed in the SrRuO3/LaA1O3 interfaces [3]. in this paper, we report the high-resolution electron microscopy study of the SrTiO3/SrRuO3 bilayer films on (100) LaA1O3 substrates. The emphasis is focused on the means of misfit relaxation at the two interfaces.Figure 1(a) is a low magnification cross-sectional image of a two-layer SrTiO3/SrRuO3 film on LaA1O3 taken along the [110] direction of the substrate. A high density of defects were observed along the SrRuO3/LaA1O3 interface. Figure 1(b) is a quarter of a superposed electron diffraction pattern (EDP) from the SrTiO3/SrRuO3 interface area, while fig. 1(c) is from the SrRuO3/LaA1O3 interface area.
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Kim, M. J., R. W. Carpenter, M. J. Cox, and J. Xu. "Controlled Planar Interface Synthesis by Ultrahigh Vacuum Diffusion Bonding/deposition." Journal of Materials Research 15, no. 4 (2000): 1008–16. http://dx.doi.org/10.1557/jmr.2000.0144.
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An ultrahigh vacuum (UHV) diffusion bonding/deposition instrument was designed and constructed, which can produce homophase and heterophase planar interfaces from a wide array of materials. The interfaces are synthesized in situ by diffusion bonding of two substrates with or without various interfacial layers, at temperatures up to about 1500 °C. Substrate surfaces can be heat treated, ion-beam sputter cleaned, and chemically characterized in situ by Auger electron spectroscopy prior to deposition and/or bonding. Bicrystals can be synthesized by bonding two single-crystal substrates at a specified orientation. Interfacial layers can be deposited by electron beam evaporation and/or sputter deposition in any layered or alloyed combination on the substrates before bonding. The instrument can accommodate cylindrical and/or wafer type specimens whose sizes are sufficient for fracture mechanical testing to measure interface bond strength. A variety of planar interfaces of metals, semiconductors, and ceramics were synthesized. Examples of bonded stainless steel/Ti/stainless steel, Si/Si, and sapphire/sapphire interfaces are presented.
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Bonera, Emiliano, and Alessandro Molle. "Optothermal Raman Spectroscopy of Black Phosphorus on a Gold Substrate." Nanomaterials 12, no. 9 (2022): 1410. http://dx.doi.org/10.3390/nano12091410.
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With black phosphorus being a promising two-dimensional layered semiconductor for application to electronics and optoelectronics, an issue remains as to how heat diffusion is managed when black phosphorus is interfaced with metals, namely in a typical device heterojunction. We use Raman spectroscopy to investigate how the laser-induced heat affects the phonon modes at the interface by comparing the experimental data with a finite element simulation based on a localized heat diffusion. The best convergence is found taking into account an effective interface thermal conductance, thus indicating that heat dissipation at the Au-supported black phosphorus nanosheets is limited by interface effect.
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Bai, Shengqiang, Fei Li, Ting Wu, Xianglin Yin, Xun Shi, and Lidong Chen. "Interface characterization of Cu–Mo coating deposited on Ti–Al alloys by arc spraying." Functional Materials Letters 08, no. 05 (2015): 1550048. http://dx.doi.org/10.1142/s1793604715500484.
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Cu – Mo pseudobinary alloys are promising candidates as electrode materials in CoSb 3-based skutterudite thermoelectric (TE) devices for TE power generation. In this study, Cu – Mo coatings were deposited onto Ti – Al substrates by applying a dual-wire electric arc spraying coating technique. The microstructure of the surfaces, cross sections and coating interfaces were analyzed by scanning electron microscopy (SEM) and energy dispersion spectrometry (EDS). Cu – Mo coatings showed a typical banded splat with compact microstructures, and have no coarse pores nor micro-cracks. The thermal shock resistance of the Cu – Mo coating was also investigated to show good combinations with Ti – Al substrates. After 50 thermal shock cycles, there were no cracks observed at the interface. In contrast, the test of the thermal shock resistance of the Cu coating on the Ti – Al substrate was also investigated. Due to a large difference in the thermal expansion coefficients between Cu and Ti – Al alloys, the Cu coating flaked from the Ti – Al substrate completely after 10 thermal shock cycles. The contact resistivity of the Ti – Al / Cu – Mo interface was about 1.6 μΩ⋅cm2 and this value was unchanged after 50 thermal shock cycles, indicating the low electric resistance and high thermal stability of the Cu – Mo / Ti – Al interface.
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Tauchmanová, Martina, Pavel Mokrý, Vít Kanclíř, Jan Václavík, Petra Veselá, and Karel Žídek. "Probing buried interfaces in SiOxNy thin films via ultrafast acoustics: The role transducing layer thickness." EPJ Web of Conferences 287 (2023): 05014. http://dx.doi.org/10.1051/epjconf/202328705014.
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Probing buried interfaces in thin films is a crucial task in many fields, including optical coating. Ultrafast acoustics provide a means to characterize the interfaces by using an acoustic wave localized on the nanometer scale. We provide a brief overview of our thorough study of the interface between SiOxNy thin films and Si substrate by using both single-color and broadband picosecond acoustics. The experiment allows us to track the effect of stoichiometry on the acoustics wave propagation and transition over the layer-substrate interface. To optimize the experiment, we also created simulations to study the effect of optoacoustic layer thickness. We show that the used Ti layer features an optimum thickness between 5-10 nm to reveal details of the interface properties.
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Ma, Kung Jeng, H. H. Chien, W. H. Chuan, Choung Lii Chao, and K. C. Hwang. "Design of Protective Coatings for Glass Lens Molding." Key Engineering Materials 364-366 (December 2007): 655–61. http://dx.doi.org/10.4028/www.scientific.net/kem.364-366.655.
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The glass molding process is considered to have a great potential for the mass production of aspherical glass lenses with high precision and low cost. However, glass molding has a serious problem of mold sticking with glass which needs to be resolved. This research investigates the interface reaction between glass and mold by high temperature wetting experiment, which provides the reference for the designing anti-stick coatings. The SUMITA K-PSK200 optical glass gobs with low Tg were used in this study. The influence of operation temperature, ambient gas, substrate materials, and thin film composition on wettability of glass at high temperature were studied. The results show that the higher the temperature, the smaller the wetting angle between glass gob and substrate could be observed. This indicates that severe interface chemical reaction occured and resulted in the loss of transparency in glass appearance. The wetting experiment in nitrogen ambient improved the sticking situation. The combination of chemically stable substrates and coatings, such as Sapphire (substrate) / GaN (film) and Glass (substrate) / Al2O3 (film) can achieve the best antistick propose. The precious metal films, such as Pt, Ir, coated on the ceramic substrates can effectively reduce the interface reaction between the glass and substrates.
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Tietz, Lisa A., C. Barry Carter, Daniel K. Lathrop, Stephen E. Russek, Robert A. Buhrman, and Joseph R. Michael. "Crystallography of YBa2Cu3O6+x thin film-substrate interfaces." Journal of Materials Research 4, no. 5 (1989): 1072–81. http://dx.doi.org/10.1557/jmr.1989.1072.
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The epitactic nature of the growth of YBa2Cu3O6+x (YBCO) superconducting thin films on ceramic substrates has been studied using high-resolution electron microscopy (HREM) and selected-area diffraction (SAD) of cross-sectional specimens. The films were grown in situ on (001)-oriented MgO and (001)-oriented Y2O3-stabilized cubic ZrO2 (YSZ) single-crystal substrates by electron beam evaporation. Both of these materials have large lattice misfits with respect to YBCO. Different orientation relationships were observed for films grown on the two types of substrates. These orientation relationships are shown to provide the best matching of the oxygen sublattices across the substrate-film interfaces. A crystalline intermediate layer, 6 nm thick, between the YBCO film and YSZ substrate was observed by HREM and shown by EDS to be a Ba-enriched phase, possibly barium zirconate formed by a reaction. In contrast, the YBCO–MgO interface was found to be sharp and free of any intermediate layers.
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Lin, Wen P., Chu-Hsuan Sha та Chin C. Lee. "40 μm Ag/Au Flip-Chip Joints by Solid-State Bonding at 200°C". Journal of Microelectronics and Electronic Packaging 10, № 3 (2013): 120–27. http://dx.doi.org/10.4071/imaps.379.
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In this research, 40 μm silver/gold (Ag/Au) composite flip-chip interconnect joints between silicon (Si) chips and copper (Cu) substrates were demonstrated. The bonding was achieved by a solid-state process at a low temperature of 200°C for 5 min with the pressure applied at 250–400 psi (1.7–2.7 MPa), corresponding to 0.22–0.35 g of force per joint. To begin with, an array of 50 × 50 30 μm Ag/10 μm Au columns with 40 μm in diameter and 100 μm in pitch was fabricated by photolitho-graphic and electroplating processes on silicon (Si) chips which were first coated with chromium (Cr) and Au films. The columns on the chip were then bonded to a Cu substrate by solid-state bonding. Cross-sectional scanning electron microscopy (SEM) images show that the exposed Ag/Au columns were well bonded to the Cu substrate. No joint breakage was observed despite the large coefficient of thermal expansion (CTE) mismatch between Si and Cu. A pull test was conducted. The breaking force and fracture strength are 6.5–7.3 kg and 2,940–3,310 psi (20.2–22.8 MPa), respectively. The breaking force is 2.5× of the criterion specified in MIL-STD-883E. Fracture modes were examined. Three modes were classified by fracture interfaces as Si-glue, Si/Cr/Au/Ag, and Au-Cu bonding interface. Of all joints evaluated, 27% of them break on the Au-Cu substrate bonding interface. Accordingly, the bonding interface is least likely to break among interfaces of the joint structure.
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Mao, Zhigang, Stuart McKernan, C. Barry Carte, Wei Yang, and Scott A. McPherson. "Horizontal Defects Parallel to the Interface in GaN Pyramids." Microscopy and Microanalysis 5, S2 (1999): 734–35. http://dx.doi.org/10.1017/s1431927600016998.
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The performance of III-V nitride-based microelectronic and optoelectronic devices relates directly to the micro structure of these materials. Selective lateral overgrowth has been exploited to produce GaN heteroepitaxial films with low defect density [1]. Si is a promising substrate due to its low cost, large size, and the potential for the intergration of GaN-based optoelectronic devices with Si-based electronics. It is also possible to produce high-quality GaN material for devices using lateral overgrowth on a Si substrate [2]. At present, only limited information on the defect structure in GaN heteroepitaxial films grown by selective lateral growth is available, especially those grown on Si substrate. Recent work [3] on GaN pyramids grown on (111) Si substrates by this method has shown that in the center, or core, of the GaN pyramid (at and above the window area) dislocations thread through the pyramid nearly perpendicular to the substrate surface and the dislocation density is quite high.
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TIAN, W. J., H. Y. ZHANG, and J. C. SHEN. "SOME PROPERTIES OF INTERFACES BETWEEN METALS AND POLYMERS." Surface Review and Letters 04, no. 04 (1997): 703–8. http://dx.doi.org/10.1142/s0218625x97000705.
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We focus on the published results of the interfaces between depositing metals and insulating and semiconducting polymers, and the interfaces between polymer films and metals. They indicated that when metal was deposited on polymer films, diffusion action occurred at the polymer surface and new interfacial states were formed during the process of deposition. Chemical reactions led to good adhesion and good performance of charge transfer between metal and polymer. When polymers were deposited on metal substrates, adsorption to the substrate occurred at the interface.
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Guo, Hong-Li, Hai-Min Li, Xue-Dong Li, Ding-Quan Xiao, and Jian-Guo Zhu. "The Effect of Substrate Clamping on Laminated Magnetoelectric Composite." Zeitschrift für Naturforschung A 66, no. 8-9 (2011): 489–94. http://dx.doi.org/10.5560/zna.2011-0012.
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Abstract laminated composites on silicon or magnesium oxide substrates. The magnetoelectric voltage coefficient is calculated as function of interface coupling factor k, volume ratio of piezoelectrics to piezomagnetic, and volume ratio of substrates to composite. It was found that the magnetoelectric voltage coefficient decreases as the interface coupling factor k weakens, while the volume ratio of piezoelectrics to piezomagnetic vmax shifts to lead-rich compositions. The magnetoelectric voltage coefficient of laminated composites decreases sharply with increasing substrates thickness ratio, which shows strong substrate clamping effect to the magnetoelectric composite.
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Ramesh, R., A. Inam, D. M. Hwang, et al. "The atomic structure of growth interfaces in Y–Ba–Cu–O thin films." Journal of Materials Research 6, no. 11 (1991): 2264–71. http://dx.doi.org/10.1557/jmr.1991.2264.
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We have examined the atomic structure of growth interfaces in thin films of Y–Ba–Cu–O grown on [001] perovskite or cubic substrates. At substrate heater temperatures in the range of 780–820 °C c-axis oriented growth is observed on these substrates. On SrTiO3, the first layer appears to be either a BaO or a CuO2 plane while on LaAlO3 the first layer appears to be a CuO chain layer. The mismatch on the a-b plane is accommodated by the formation of interface dislocations. Defects on the substrate surface propagate as defects in the film. These defects are primarily translational boundaries and in some cases second phases. At lower substrate heater temperatures, i.e., 650–700 °C, a, b-axis growth dominates. Defects and steps on the substrate surface are more detrimental in the growth of a, b-axis oriented films, since they tend to favor the nucleation of c-axis oriented domains. This is ascribed to the ledge mechanism of c-axis film growth, for which the surface steps are good nucleation sites.
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Isshiki, Toshiyuki, Koji Nishio, Yoshihisa Abe, Jun Komiyama, Shunichi Suzuki, and Hideo Nakanishi. "HRTEM Analysis of AlN Layer Grown on 3C-SiC/Si Heteroepitaxial Substrates with Various Surface Orientations." Materials Science Forum 600-603 (September 2008): 1317–20. http://dx.doi.org/10.4028/www.scientific.net/msf.600-603.1317.
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Epitaxial growth of AlN was carried out by MOVPE method on SiC/Si buffered substrates prepared by using various Si surfaces of (110), (211) and (001). Cross-sectional HRTEM analyses of the interfaces between SiC buffer layer and AlN epitaxial layer disclosed characteristic nanostructures related growth mechanism on the each substrate. In the case of Si(110) and Si(211) substrate, hexagonal AlN grew directly on SiC(111) plane with AlN(0001) plane parallel to it. In contrast, growth on Si(001) substrate gave complicate structure at AlN/SiC interface. Hexagonal AlN didn’t grow directly but cubic AlN appeared with a pyramidal shape on SiC(001). When the cubic AlN grew 10nm in height, structure of growing AlN crystal changed to hexagonal type on the pyramidal {111} planes of cubic AlN.
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Bahadur, V., J. Xu, Y. Liu, and T. S. Fisher. "Thermal Resistance of Nanowire-Plane Interfaces." Journal of Heat Transfer 127, no. 6 (2005): 664–68. http://dx.doi.org/10.1115/1.1865217.
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This paper employs continuum principles combined with van der Waals theory to estimate the thermal contact resistance between nanowires and planar substrates. This resistance is modeled using elastic deformation theory and thermal resistance relations. The contact force between a nanowire and substrate is obtained through a calculation of the van der Waals interaction energy between the two. The model estimates numerical values of constriction and gap resistances for several nanowire-substrate combinations with water and air as the surrounding media. The total interface resistance is almost equal to the gap resistance when the surrounding medium has a high thermal conductivity. For a low-conductivity medium, the interface resistance is dominated by the constriction resistance, which itself depends significantly on nanowire and substrate conductivities. A trend observed in all calculations is that the interface resistance increases with smaller nanowires, showing that interface resistance will be a significant parameter in the design and performance of nanoelectronic devices.
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Vanfleet, R. R., M. Shverdin, Z. H. Zhu, Y. H. Lo, and J. Silcox. "Interface Voids and Precipitates in GaAs Wafer Bonding." Microscopy and Microanalysis 5, S2 (1999): 748–49. http://dx.doi.org/10.1017/s1431927600017062.
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Wafer bonding allows the production of Compliant Universal substrates that are made by bonding a thin (< 10 nm) layer twisted ∼45 degrees to the underlying substrate. Subsequent growth on this twisted layer results in defect free films even when the growth material has a significant lattice mismatch with the substrate. Defects on the bonding interface are a common observation when bonding GaAs to many substrates, but the exact nature of these defects has not been clear. We have studied this bonding layer in GaAs-GaAs twist bonded structures by Scanning Transmission Electron Microscopy and Electron Energy Loss Spectroscopy and established that the defects are voids with a portion being partially filled with gallium. Two general sizes of voids are seen. The larger voids are approximately 45 nm in diameter and 22 nm in the wafer normal direction and are distributed in an approximately linear relationship.
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Kawai, Kakisawa, Kubo, et al. "Crack Initiation Criteria in EBC under Thermal Stress." Coatings 9, no. 11 (2019): 697. http://dx.doi.org/10.3390/coatings9110697.
Full textAbstract:
For design of multi-layered environmental barrier coatings (EBCs), it is essential to assure mechanical reliability against interface crack initiation and propagation induced by thermal stress owing to a misfit of the coefficients of thermal expansion between the coating layers and SiC/SiC substrate. We conducted finite element method (FEM) analyses to evaluate energy release rate (ERR) for interface cracks and performed experiment to obtain interface fracture toughness to assess mechanical reliability of an EBC with a function of thermal barrier (T/EBC; SiC/SiAlON/mullite/Yb-silicate gradient composition layer/Yb2SiO5 with porous segment structure) on an SiC/SiC substrate under thermal stress due to cooling in fabrication process. Our FEM analysis revealed that a thinner SiAlON layer and a thicker mullite layer are most suitable to reduce ERRs for crack initiation at the SiC/SiAlON, SiAlON/mullite and mullite/Yb2Si2O7 interfaces. Interface fracture tests of the T/EBC with layer thicknesses within the proposed range exhibited fracture at the SiC/SiAlON and SiAlON/mullite interfaces. We also estimated the approximate fracture toughness for the SiC/SiAlON and SiAlON/mullite interfaces and lower limit of fracture toughness for the mullite/Yb2Si2O7 interface. Comparison between ERR and fracture toughness indicates that the fabricated T/EBC possesses sufficient mechanical reliability against interface crack initiation and propagation.
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Tietz, Lisa A., Scott R. Summerfelt, and C. Barry Carter. "Growth of hematite on (0001) and {1102} sapphire substrates." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 4 (1990): 376–77. http://dx.doi.org/10.1017/s0424820100175016.
Full textAbstract:
Defects in thin films are often introduced at the substrate-film interface during the early stages of growth. The interface structures of semiconductor heterojunctions have been extensively studied because of the electrical activity of defects in these materials. Much less attention has been paid to the structure of oxide-oxide heterojunctions. In this study, the structures of the interfaces formed between hematite (α-Fe2O3) and two orientations of sapphire (α-Al2O3) are examined in relationship to the defects introduced into the hematite film. In such heterojunctions, the oxygen sublattice is expected to have a strong influence on the epitaxy; however, defects which involve only the cation sublattice may be introduced at the interface with little increase in interface energy.Oxide heterojunctions were produced by depositing small quantities of hematite directly onto electrontransparent sapphire substrates using low-pressure chemical vapor deposition. Prior to deposition, the ionthinned substrates were chemically cleaned and annealed at 1400°C to give “clean”, crystalline surfaces. Hematite was formed by the reaction of FeCl3 vapor with water vapor at 1150°C and 1-2 Torr. The growth of the hematite and the interface structures formed on (0001) and {102} substrates have been studied by bright-field, strong- and weak-beam dark-field imaging techniques.
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Schloesser, Jana, Martin Bäker, Joachim Rösler, and Robert Pulz. "Oxidation Behavior of Thermal Barrier Coatings on Copper Substrates." Advances in Science and Technology 66 (October 2010): 74–79. http://dx.doi.org/10.4028/www.scientific.net/ast.66.74.
Full textAbstract:
In rocket engine combustion chambers, the cooling channels experience extremely high temperatures and environmental attack. Thermal protection can be provided by Thermal Barrier Coatings. Due to the need of good heat conduction, the inner combustion liner is made of copper. The performance of a standard coating system for nickel based substrates is investigated on copper substrates. Thermal cycling experiments are performed on the coated samples. Due to temperature limitations of the copper substrate material, no thermally grown oxide forms at the interface of the thermal barrier coating and the bond coat. Delamination of the coatings occurs at the interface between the substrate and the bond coat due to oxide formation of the copper at uncoated edges. In real service a totally dense coating can probably not be assured which is the reason why this failure mode is of importance. Different parameters are used for thermal cycling to understand the underlying mechanisms of delamination. Furthermore, laser heating experiments account for the high thermal gradient in real service. Pilot tests which led to a delamination of the coating at the substrate interface were performed successfully.