Articoli di riviste: "Thin film, epitaxial"

1

Ito, Akihiko, Hiroshi Masumoto e Takashi Goto. "Morphology of Epitaxially Grown BaRuO₃ and CaRuO₃ Thin Films by Laser Ablation". Key Engineering Materials 352 (agosto 2007): 315–18. http://dx.doi.org/10.4028/www.scientific.net/kem.352.315.

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Epitaxial BaRuO3 (BRO) and CaRuO3 (CRO) thin films were prepared on (001), (110) and (111) SrTiO3 (STO) single-crystal substrates by laser ablation, and their microstructures and anisotropy of electrical conductivity were investigated. The (205) (104), (110) and (009) oriented BRO thin films, and (001), (110) and (110) oriented CRO thin films were grown epitaxially on (001), (110) and (111) STO substrates with in-plain orientation, respectively. The (009) BRO thin film and (001) CRO thin film has a flat surface result from a good lattice matching to STO substrates. The (205) (104) BRO thin film and (111) CRO thin film exhibited orthogonal- and hexagonal-shaped texture, respectively. The (110) BRO thin film and (110) CRO thin film showed an island growth due to (110) surface feature of cubic perovskite structure. Epitaxial BRO and CRO thin films have a high electrical conductivity with a metallic conduction, the (111) CRO thin films exhibited the highest conductivity of 1.4×105 S·m-1.

2

Seifert, Andreas, Fred F. Lange e James S. Speck. "Epitaxial growth of PbTiO3 thin films on (001) SrTiO3 from solution precursors". Journal of Materials Research 10, n. 3 (marzo 1995): 680–91. http://dx.doi.org/10.1557/jmr.1995.0680.

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A mixed alkoxide liquid precursor was used to form epitaxial PbTiO3 thin films by spin-coating on cubic (001) SrTiO3 substrates. The films were heat-treated at temperatures between 380 °C/1 h and 800 °C/1 h. X-ray diffraction, atomic force microscopy, scanning and transmission electron microscopy were used to characterize the microstructure of the films and to evaluate the epitaxial phenomena. At ∼400 °C/1 h, a polycrystalline, metastable Pb-Ti fluorite crystallizes from the pyrolyzed amorphous precursor. At slightly higher temperatures (∼420 °C/1 h), the thermodynamically stable phase with the perovskite structure epitaxially nucleates at the film/substrate interface. A small number of epitaxial grains grow through the film toward the surface and consume the nanocrystalline fluorite grains. Coarsening of the perovskite grains leads to a reduction in mosaic spread during further heating. Pores, which concurrently coarsen with grain growth, produce a pitted surface as they disappear from within the film. At 800 °C/1 ha dense epitaxial PbTiO3 film with a smooth surface is observed. Parameters governing the formation of a- and c-domains are discussed as well as the small tilts of the domain axes away from the substrate normal.

3

Miyake, A., H. Kominami, T. Aoki, H. Tatsuoka, H. Kuwabara, Y. Nkanishi e Y. Hatanaka. "Growth of epitaxial ZnO thin film by oxidation of epitaxial ZnS thin films on Si(111)". International Journal of Modern Physics B 15, n. 28n30 (10 dicembre 2001): 3861–64. http://dx.doi.org/10.1142/s0217979201008858.

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The growth of epitaxial ZnO thin film on Si substrate by the oxidation of epitaxial ZnS film is a novel method and we are reporting this first time. The merits of the use of Si substrate are to make driving voltage in LED lower and less expensive than sapphire substrate. In this study, the epitaxial ZnO thin film could be successfully grown on the Si substrate. The epitaxial films showed a strong near ultraviolet emission peaked at around 3.32 eV at room temperature under 325 nm excitation.

4

Tamaki, Jun, Gregory K. L. Goh e Fred F. Lange. "Novel epitaxial growth of barium titanate thin films by electrodeposition". Journal of Materials Research 15, n. 12 (dicembre 2000): 2583–86. http://dx.doi.org/10.1557/jmr.2000.0368.

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Electrodeposition was used to grow epitaxially BaTiO3 thin films on SrTiO3 single-crystal substrates with La0.7Sr0.3MnO3 (LSMO) conducting buffer layers. The epitaxial films appeared to consist of very small (ø10 nm) particles. The film completely covered the substrate when the reaction was performed at temperatures between 60 and 90 °C with LSMO potentials of –0.5 to –1.0 V against a Pt counter-electrode. It appeared that an electrophoretic force, acting on BaTiO3 nuclei within the solution, facilitated the deposition of the film.

5

DeNatale, J. F., e P. H. Kobrin. "Lattice distortion effects on electrical switching in epitaxial thin film NdNiO3". Journal of Materials Research 10, n. 12 (dicembre 1995): 2992–95. http://dx.doi.org/10.1557/jmr.1995.2992.

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Crystalline thin films of NdNiO3 have been epitaxially grown on the (100) face of single-crystal LaAlO3 substrates. These films exhibit the characteristic reversible change in electrical conductivity with temperature previously observed in bulk polycrystalline material. The temperature of the electrical transition in the epitaxial thin films was lower than reported for the bulk polycrystalline ceramics. This effect is attributed to lattice strains associated with the film processing and interfacial lattice matching constraints.

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Sasi, Krishnaprasad, Sebastian Mailadil, Fredy Rojas, Aldrin Antony e Jayaraj Madambi. "Buffer Assisted Epitaxial Growth of Bi1.5Zn1Nb1.5O7 Thin Films by Pulsed Laser Deposition for Optoelectronic Applications". MRS Proceedings 1454 (2012): 183–88. http://dx.doi.org/10.1557/opl.2012.1264.

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ABSTRACTBi1.5Zn1Nb1.5O7 (BZN) epitaxial thin films were prepared on Al2O3with a double ZnO buffer layer by pulsed laser deposition. The pole figure analysis and reciprocal space mapping revealed the single crystalline nature of the thin film. The sharp intense spots in the SAED pattern also indicates the highly crystalline nature of BZN thin film. The electrical properties of the as deposited thin films were investigated by patterning an inter digital capacitor (IDC) structure on BZN. A high tunability was observed in this epitaxially grown thin films.

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Miller, Dean J., Jeffrey D. Hettinger, Ronald P. Chiarello e Hyung K. Kim. "Epitaxial growth of Cu2O films on MgO by sputtering". Journal of Materials Research 7, n. 10 (ottobre 1992): 2828–32. http://dx.doi.org/10.1557/jmr.1992.2828.

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The epitaxial growth of Cu2O films is of significant interest for the unique potential they offer in the development of multilayer devices and superlattices. While fundamental studies may be carried out on epitaxial films prepared by any technique, the growth of artificially layered superlattices requires that films grow epitaxially during deposition. The present study examined the growth of Cu2O on MgO substrates directly during deposition by sputtering. Although epitaxial thin films of Cu2O could be produced, a mosaic structure was observed. The structure of the film may be related to the growth mechanism in which islands coalesce to form a continuous film.

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Jiang, J. C., X. Q. Pan, Q. Gan e C. B. Eom. "Domain Structure of Epitaxial SrRuO3 Thin Films on (001) LaA1O3". Microscopy and Microanalysis 4, S2 (luglio 1998): 578–79. http://dx.doi.org/10.1017/s1431927600023011.

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Epitaxial thin film of SrRuO3 is very useful in device applications, due to its important electrical and magnetic properties. For example, (Pb,Zr)TiO3 ferroelectric capacitors with SrRuO3 thin film electrodes exhibit superior fatigue and leakage characteristics. Epitaxial SrRuO3 thin films grown on different substrates, such as on (001) SrTiO3 and (001) LaA1O3, have different magnetic properties, owing to the different microstructures in the film. Microstructures in epitaxial SrRuO3 thin films grown on (001) SrTiO3 have been studied in our previously work. In this paper, microstructure of epitaxial SrRu03 thin films grown on (001) LaA103 is reported.SrRuO3 thin films on (001) LaA1O3 were deposited by 90° off-axis sputtering. For cross-section TEM studies the SrRuO3/LaA1O3 heterostructural samples were cut along the [100] direction of LaA103. The cut slides were glued face-to-face by joining the SrRu03 surfaces. Plan-view and cross-section TEM specimens were prepared by mechanical grinding, polishing and dimpling, followed by Ar-ion milling.

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Wasa, Kiyotaka, Toshifumi Satoh, Kenji Tabata, Hideaki Adachi, Yasumufi Yabuuchi e Kentaro Setune. "Effects of PLT-buffer layer on microstructures of sputtered PLZT thin films epitaxially grown on sapphire". Journal of Materials Research 9, n. 11 (novembre 1994): 2959–67. http://dx.doi.org/10.1557/jmr.1994.2959.

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The microstructures of sputtered thin films of lead-lanthanum zirconate-titanate (PLZT) on (0001) sapphire substrate have been studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Thin films of polycrystalline PLZT (9/65/35), Pb0.91La0.09Zr0.65Ti0.35O3, were prepared on a (0001) sapphire substrate by reactive sputtering, using the dc-magnetron system with a multitarget, Pb, La, Zr, and Ti at the substrate temperature of 700 °C. The PLZT thin films comprised (111) oriented small crystallites of PLZT. Although the average direction of the crystal orientation corresponded to the ideal epitaxial relationship (111) PLZT ‖ (0001) sapphire, the individual crystallites showed misalignment in both the growth direction and the film plane. The thin films could not be considered epitaxially grown films. From analysis of the TEM images, there exists an interfacial region between the PLZT thin film and the substrate. The interfacial region comprises ordered clusters of (111), disordered (101), and/or (110) PLZT crystallites. The presence of the interfacial region will suppress ideal epitaxial growth with uniform crystal orientation. It is confirmed that the addition of the buffer layer of graded composition of PLT-PLZT, between the substrate and the PLZT thin film, will suppress the formation of the disordered interfacial region and will enhance the epitaxial growth of the (111) PLZT on (0001) sapphire with three-dimensional crystal orientations.

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Kim, J. H., e F. F. Lange. "Seeded Epitaxial Growth of PbTiO3 Thin Films on (001) LaAlO3 using the Chemical Solution Deposition Method". Journal of Materials Research 14, n. 4 (aprile 1999): 1626–33. http://dx.doi.org/10.1557/jmr.1999.0218.

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Epitaxial PbTiO3 (PTO) thin films were grown on (001) LaAlO3 (LAO) substrates by a preseeded, two-step process via spin coating a Pb–Ti double alkoxide precursor solution. In the first step, a substrate was preseeded with epitaxial islands of PTO by coating the substrate with a very thin layer of the precursor solution and heat treating to 800 °C for 1 h. The isolated islands had an epitaxial orientation relationship of [100] (001)PTO || [100] (001)LAO. In the second step, another PTO thin film was deposited by spin coating to produce an epitaxial film via grain growth from the seeded islands. The sequence of epitaxy during heating between 400 and 800 °C was characterized by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy (TEM). This sequence was compared to the case where the LAO substrate was not seeded. Regardless of whether the substrate was seeded or not, perovskite PTO grains nucleated and grew within the pyrolyzed, amorphous film. Films grown on the unseeded substrates were, at best, only highly textured, polycrystalline films. TEM observations showed that only a low number of epitaxial nuclei formed at the substrate/film interface due, apparently, to the large strain energy associated with the large lattice mismatch (~4%) between PTO and LAO. Other, unoriented, PTO grains that nucleated within the amorphous film were not consumed as the epitaxial grains grew larger with increasing temperature. On the other hand, good epitaxial films could be produced when the number density of epitaxial nuclei was increased by first forming a seeded substrate.

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Ngoc Thao, Pham, Shinya Yoshida e Shuji Tanaka. "Fabrication and Characterization of PZT Fibered-Epitaxial Thin Film on Si for Piezoelectric Micromachined Ultrasound Transducer". Micromachines 9, n. 9 (11 settembre 2018): 455. http://dx.doi.org/10.3390/mi9090455.

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This paper presents a fibered-epitaxial lead zirconate titanate (PZT) thin film with intermediate features between the monocrystalline and polycrystalline thin films for piezoelectric micromachined ultrasound transducer (pMUT). The grain boundaries confirmed by scanning electron microscopy, but it still maintained the in-plane epitaxial relationship found by X-ray diffraction analyses. The dielectric constant (εr33 = 500) was relatively high compared to those of the monocrystalline thin films, but was lower than those of conventional polycrystalline thin films near the morphotropic phase boundary composition. The fundamental characterizations were evaluated through the operation tests of the prototyped pMUT with the fibered-epitaxial thin film. As a result, its piezoelectric coefficient without poling treatment was estimated to be e31,f = −10–−11 C/m2, and thus reasonably high compared to polycrystalline thin films. An appropriate poling treatment increased e31,f and decreased εr33. In addition, this unique film was demonstrated to be mechanically tougher than the monocrystalline thin film. It has the potential ability to become a well-balanced piezoelectric film with both high signal-to-noise ratio and mechanical toughness for pMUT.

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Chattopadhyay, Soma, A. R. Teren, Jin-Ha Hwang, T. O. Mason e B. W. Wessels. "Diffuse Phase Transition in Epitaxial BaTiO3 Thin Films". Journal of Materials Research 17, n. 3 (marzo 2002): 669–74. http://dx.doi.org/10.1557/jmr.2002.0095.

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The thickness dependence of the dielectric properties of epitaxial BaTiO3 thin films was investigated for thicknesses ranging from 15 to 320 nm. The films were deposited by low-pressure metalorganic chemical vapor deposition on (100) MgO substrates. The relative dielectric permittivity and the loss tangent values decreased with decreasing thickness. High-temperature dielectric measurements showed that with decreasing film thickness, the ferroelectric-to-paraelectric transition temperature decreased, the relative dielectric permittivity decreased, and the phase transition was diffuse. The c/a ratio also decreased with decreasing film thickness. The observed behavior for epitaxial films of BaTiO3 was attributed to the presence of strain in the films.

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Bergmann, R. B., T. J. Rinke, R. M. Hausner, M. Grauvogl, M. Vetter e J. H. Werner. "Thin film solar cells on glass by transfer of monocrystalline Si films". International Journal of Photoenergy 1, n. 2 (1999): 89–93. http://dx.doi.org/10.1155/s1110662x99000173.

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Thin film solar cells based on monocrystalline Si films are transferred to a glass superstrate. Chemical vapor deposition serves to epitaxially deposit Si on quasi-monocrystalline Si films obtained from thermal crystallization of a double layer porous Si film on a Si wafer. A separation layer that forms during this crystallization process allows one to separate the epitaxial layer on top of the quasi-monocrystalline film from the starting Si wafer. We presently achieve an independently confirmed solar cell conversion efficiency of 9:26%. Ray tracing studies in combination with electrical device simulation indicate an efficiency potential of around 17% using simple device processing and moderate assumptions on minority carrier lifetime and surface recombination.

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Moustakas, Theodore D. "Molecular Beam Epitaxy: Thin Film Growth and Surface Studies". MRS Bulletin 13, n. 11 (novembre 1988): 29–36. http://dx.doi.org/10.1557/s0883769400063892.

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Molecular Beam Epitaxy (MBE) is a thin film deposition process in which thermal beams of atoms or molecules react on the clean surface of a single-crystalline substrate, held at high temperatures under ultrahigh vacuum conditions, to form an epitaxial film. Thus, contrary to the CVD processes described in the other articles, the MBE process is a physical method of thin film deposition.The vacuum requirements for the MBE process are typically better than 10−10torr. This makes it possible to grow epitaxial films with high purity and excellent crystal quality at relatively low substrate temperatures. Additionally, the ultrahigh vacuum environment allows the study of surface, interface, and bulk properties of the growing film in real time, by employing a variety of structural and analytical probes.Although the MBE deposition process was first proposed by Günther in 1958, its implementation had to wait for the development of the ultrahigh vacuum technology. In 1968 Davey and Pankey successfully grew epitaxial GaAs films by the MBE process. At the same time Arthur's work on the kinetics of GaAs growth laid the groundwork for the growth of high quality MBE films of GaAs and other III-V compounds by Arthur and LePore and Cho.

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Lee, Daesu, e Tae Won Noh. "Giant flexoelectric effect through interfacial strain relaxation". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 370, n. 1977 (28 ottobre 2012): 4944–57. http://dx.doi.org/10.1098/rsta.2012.0200.

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Interfacial strain gradients in oxide epitaxial thin films provide an interesting opportunity to study flexoelectric effects and their potential applications. Oxide epitaxial thin films can exhibit giant and tunable flexoelectric effects, which are six or seven orders of magnitude larger than those in conventional bulk solids. The strain gradient in an oxide epitaxial thin film can generate an electric field above 1 MV m −1 by flexoelectricity, large enough to affect the physical properties of the film. Giant flexoelectric effects on ferroelectric properties are discussed in this overview of recent experimental observations.

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Liu, Haifeng, Yuqiao Guo, Ruishi Xie e Guohua Ma. "Epitaxial Growth of Strain-Induced Ferromagnetic LaCoO3 Thin Films by Simple Sol–Gel Technique". Nano 11, n. 03 (marzo 2016): 1650030. http://dx.doi.org/10.1142/s1793292016500302.

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LaCoO3 (LCO) epitaxial films were grown on (001) LaAlO3 (LAO) substrates by the simple sol–gel technique. X-ray diffraction (XRD) and the cross-section transmission electron microscope (TEM) measurements indicate that single-phase (001) oriented LCO epitaxial films with biaxial compressive strain and elongated distortion of CoO6 octahedrons were grown on (001) LAO successfully. The epitaxial relationship between the LCO film and the LAO substrate is confirmed to be (001)[Formula: see text] and [100][Formula: see text]. It is also found that LCO grown on LAO has a larger mean Co–O bond length and unit-cell size, compared with those of polycrystalline film. In addition, the magnetic characterization shows that LCO epitaxial film exhibits an obvious ferromagnetic (FM) transition at [Formula: see text][Formula: see text]K, which is different from the nonmagnetic ground state of polycrystalline LCO. Combined with the structural analyses, it reveals that the strain-induced ferromagnetism observed in LCO epitaxial film originates from an increase of the mean Co–O bond length and a suppression of the CoO6 octahedral rotations, which can stabilize higher spin state of Co[Formula: see text] by a decrease of the [Formula: see text] gap energy.

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Cheng, Xiankun, Qiang Gao, Kaifeng Li, Zhongliang Liu, Qinzhuang Liu, Qiangchun Liu, Yongxing Zhang e Bing Li. "Enhanced Phase Transition Properties of VO2 Thin Films on 6H-SiC (0001) Substrate Prepared by Pulsed Laser Deposition". Nanomaterials 9, n. 8 (24 luglio 2019): 1061. http://dx.doi.org/10.3390/nano9081061.

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For growing high quality epitaxial VO2 thin films, the substrate with suitable lattice parameters is very important if considering the lattice matching. In addition, the thermal conductivity between the substrate and epitaxial film should be also considered. Interestingly, the c-plane of hexagonal 6H-SiC with high thermal conductivity has a similar lattice structure to the VO2 (010), which enables epitaxial growth of high quality VO2 films on 6H-SiC substrates. In the current study, we deposited VO2 thin films directly on 6H-SiC (0001) single-crystal substrates by pulsed laser deposition (PLD) and systematically investigated the crystal structures and surface morphologies of the films as the function of growth temperature and film thickness. With optimized conditions, the obtained epitaxial VO2 film showed pure monoclinic phase structure and excellent phase transition properties. Across the phase transition from monoclinic structure (M1) to tetragonal rutile structure (R), the VO2/6H-SiC (0001) film demonstrated a sharp resistance change up to five orders of magnitude and a narrow hysteresis width of only 3.3 °C.

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Seifert, A., A. Vojta, J. S. Speck e F. F. Lange. "Microstructural instability in single-crystal thin films". Journal of Materials Research 11, n. 6 (giugno 1996): 1470–82. http://dx.doi.org/10.1557/jmr.1996.0183.

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Epitaxial PbTiO3 thin films were produced from a mixed Pb–Ti double-alkoxide precursor by spin-coating onto single crystal (001) SrTiO3 substrates. Heat treatment at 800 °C produces a dense and continuous, epitaxial lead titanate film through an intermediate Pb-Ti fluorite structure. A microstructural instability occurred when very thin single crystal films were fabricated; this instability caused the films to become discontinuous. Scanning electron microscopy and atomic force microscopy observations show that single crystal films with a thickness less than ∼80 nm developed holes that expose the substrate; thinner films broke up into isolated, single crystal islands. The walls of the holes were found to be (111) perovskite planes. A free energy function, which considered the anisotropic surface energies of different planes, was developed to describe the microstructural changes in the film and to understand the instability phenomenon. The function predicted that pre-existing holes greater than a critical size are necessary to initiate hole growth, and it predicted the observed morphological changes in the current system. Morphological stability diagrams that explain the stability fields for different film configurations, i.e., either completely covered, with holes, or single crystal islands, can be calculated for any film/substrate system.

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Resel, Roland, Markus Koini, Jiri Novak, Steven Berkebile, Georg Koller e Michael Ramsey. "Epitaxial Order Driven by Surface Corrugation: Quinquephenyl Crystals on a Cu(110)-(2×1)O Surface". Crystals 9, n. 7 (22 luglio 2019): 373. http://dx.doi.org/10.3390/cryst9070373.

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A 30 nm thick quinquephenyl (5P) film was grown by molecular beam deposition on a Cu(110)(2×1)O single crystal surface. The thin film morphology was studied by light microscopy and atomic force microscopy and the crystallographic structure of the thin film was investigated by X-ray diffraction methods. The 5P molecules crystallise epitaxially with (201)5P parallel to the substrate surface (110)Cu and with their long molecular axes parallel to [001]Cu. The observed epitaxial alignment cannot be explained by lattice matching calculations. Although a clear minimum in the lattice misfit exists, it is not adapted by the epitaxial growth of 5P crystals. Instead the formation of epitaxially oriented crystallites is determined by atomic corrugations of the substrate surface, such that the initially adsorbed 5P molecules fill with its rod-like shape the periodic grooves of the substrate. Subsequent crystal growth follows the orientation and alignment of the molecules taken within the initial growth stage.

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Fang, Y., V. R. Sakhalkar, J. He, H. Q. Jiang, Jiechao Jiang e Efstathios I. Meletis. "Growth, Microstructure and Properties of Epitaxial La_1-XSr_xMnO₃ Thin Films on Various Substrates Using RF Magnetron Sputtering". Journal of Nano Research 14 (aprile 2011): 83–92. http://dx.doi.org/10.4028/www.scientific.net/jnanor.14.83.

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Synthesis of high quality epitaxial LaMnO3 and (La,Sr)MnO3 films on large areas is highly desirable. Recently, we have deposited LaMnO3 and (La,Sr)MnO3 films on the MgO (001) and LaAlO3 (001) substrates using RF magnetron sputtering. Highly epitaxial quality thin films have been successfully obtained at 750 °C by manipulating processing parameters as characterized by X-ray diffraction, electron diffraction and HRTEM. The epitaxial LaMnO3 and (La,Sr)MnO3 thin films have either a tetragonal or orthorhombic crystal structure depending on the film (target) composition and substrate type. The (La,Sr)MnO3 films were found to have an orthorhombic crystal structure when deposited on LaAlO3 substrate and a tetragonal structure when deposited on MgO substrate; whereas LaMnO3 films have a tetragonal structure when deposited on LaAlO3 substrate and an orthorhombic crystal structure when deposited on MgO substrate. The orthorhombic structures of the (La,Sr)MnO3 film on LaAlO3 and LaMnO3 on MgO are oriented with their c-axis on the film plane. Magnetic studies show that the epitaxial films have higher phase transition temperature than the corresponding bulk material and to those obtained using pulse laser deposition. Successful synthesis of highly epitaxial quality films by RF magnetron sputtering over a larger area can result in reduced cost for fabricating and processing epitaxial thin films.

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Nashimoto, Keiichi, Michael J. Cima, Paul C. McIntyre e Wendell E. Rhine. "Microstructure development of sol-gel derived epitaxial LiNbO3 thin films". Journal of Materials Research 10, n. 10 (ottobre 1995): 2564–72. http://dx.doi.org/10.1557/jmr.1995.2564.

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Film growth and microstructural evolution were investigated for sol-gel derived LiNbO3 thin films deposited on lattice-matched single-crystal substrates. Epitaxial LiNbO3 films of about 100 nm nominal thickness were prepared by spin coating a solution of the lithium niobium ethoxide on sapphire (0001) substrates and annealing at 400 °C or 700 °C in a humidified oxygen atmosphere. These films exhibited an epitaxial relationship with the substrate of the type LiNbO3 (0001) || α-Al2O3 (0001) and LiNbO3 [100] || α-Al2O3 [100] as determined by x-ray pole figure analysis. Transmission electron microscopy indicated the epitaxial films annealed at 400 °C consisted of slightly misoriented ∼5 nm subgrains and of numerous ∼10 nm enclosed pores. The microstructure and orientation development of these films was consistent with a heteroepitaxial nucleation and growth mechanism, in which epitaxial nuclei form at the substrate surface and grow upward into an amorphous and porous intermediate film: Epitaxial films annealed at 700 °C contained larger 150-200 nm subgrains and pinholes. Misorientations between adjacent subgrains appeared to be significantly smaller in films annealed at 700 °C than those in films annealed at 400 °C. Hydrolysis of the alkoxide precursor solution prior to spin coating promoted the development of polycrystalline films on single-crystal sapphire substrates. Infrared spectra and thermal analysis indicated that, independent of the degree of the solution hydrolysis, nucleation of LiNbO3 was immediately preceded by decomposition of an amorphous carbonate intermediate phase.

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Derouin, T. A., C. D. E. Lakeman, X. H. Wu, J. S. Speck e F. F. Lange. "Effect of lattice mismatch on the epitaxy of sol-gel LiNbO3 thin films". Journal of Materials Research 12, n. 5 (maggio 1997): 1391–400. http://dx.doi.org/10.1557/jmr.1997.0189.

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A solution precursor method based on metal alkoxides was used to produce epitaxial LiNbO3 thin films, ≈200 nm thick, on (0001) sapphire substrates. Transmission electron. microscopy revealed that the major cause of surface roughness in these films was grain boundary grooves between mosaic grains with misorientations ≤5°. It is postulated that these low angle boundaries directly result in surface grooving and roughness. The epitaxial films also contained two distinguishable variants in the film/substrate interfacial plane, namely, an aligned variant, and a 60° rotated variant, . A seeded grain growth method was used to minimize the presence of the 60° rotated variant. An epitaxial buffer layer of Fe2O3 was used to lower the mismatch strain, eliminate the 60° rotated variant, and reduce the mosaic nature of the LiNbO3 film. X-ray rocking curve full-width-at-half-maximum (FWHM) values measured on the film peak indicate that the mosaic character can be reduced from 1.5° to 0.76° by using a buffer layer.

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Nemoto, Naru, Naoki Wakiya, Kazuo Shinozaki, Takanori Kiguchi, Keisuke Satoh, Masatoshi Ishii, Masao Kondo, Kazuaki Kurihara e Nobuyasu Mizutani. "Preparation and Optical Properties of Epitaxial Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ Thin Film on Si Substrates with Buffer Layer Using Pulsed Laser Deposition". Key Engineering Materials 301 (gennaio 2006): 265–68. http://dx.doi.org/10.4028/www.scientific.net/kem.301.265.

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Epitaxial Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) thin films for electrooptic applications were fabricated on a Si substrate using buffer layers. The PMN-PT/SrRuO3/SrTiO3/(La,Sr)CoO3/CeO2 /YSZ/Si hetrostructure was fabricated by pulsed laser deposition. A PMN-PT thin film with a thickness of 2μm was successfully deposited. The optical characteristics of PMN-PT epitaxial film were measured by prism coupling method. The morphology of the PMN-PT films was drastically improved by introducing a mask between the target and substrate during the deposition. The PMN-PT thin film showed a columnar structure, where the width of each column was approximately 180nm. A refractive index of 2.48 with zero bias voltage was obtained for the epitaxial PMN-PT thin film using the prism coupler method.

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Shaikhulov, Timur A., Valery A. Shakhunov, Victor V. Demidov, Gennady A. Ovsyannikov, Nikolay V. Andreev, Anna E. Pestun e Vladimir L. Preobrazhensky. "Strain effect on resistivity of La0.7Ba0.3MnO3 thin film". EPJ Web of Conferences 185 (2018): 06006. http://dx.doi.org/10.1051/epjconf/201818506006.

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A complex study of the dc and magnetic characteristics of epitaxial manganite films La0.7Ba0.3MnO3 (LBMO) was carried out under conditions of the crystal structure tension caused by a mismatch between the parameters of the LBMO crystal and the substrate. The epitaxial thin films with the thickness 150 nm were grown by laser ablation at T=700-800C under pure oxygen pressure 0.3-1 mbar. The substrates (001)LaAlO3, (001)SrTiO3, (110)NdGaO3, (001)[(LaAlO3)0.3+(Sr2AlTaO6)0.7] (LSAT) are used. It is shown that the temperature dependence of the film resistance in the low-temperature region does not depend on the film strain and it is in good agreement with the calculation that takes into account the interaction of carriers with magnetic excitations in the presence of strongly correlated electron states. The study of the of ferromagnetic resonance indicated the inhomogeneity of the ferromagnetic phase in LBMO films and an increase in the width of the FMR line with temperature decreasing.

25

Kim, Jihong. "Low-Temperature Epitaxial Growth of AlN Thin Films on a Mo Electrode/Sapphire Substrate Using Reactive Sputtering". Coatings 11, n. 4 (12 aprile 2021): 443. http://dx.doi.org/10.3390/coatings11040443.

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High-crystalline aluminum nitride (AlN) thin films are essential for device applications, and epitaxial growth is a promising approach to improve their crystalline quality. However, a high substrate temperature is usually required for the epitaxial growth, which is not compatible with the complementary metal-oxide-semiconductor (CMOS) process. Furthermore, it is very difficult to obtain epitaxial AlN thin films on the deposited metal layers that are sometimes necessary for the bottom electrodes. In this work, epitaxial AlN thin films were successfully prepared on a molybdenum (Mo) electrode/sapphire substrate using reactive sputtering at a low substrate temperature. The structural properties, including the out-of-plane and in-plane relationships between the AlN thin film and the substrate, were investigated using X-ray diffraction (XRD) 2θ-ω, rocking curve, and pole figure scans. Additional analyses using scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM) were also carried out. It was shown that highly c-axis-oriented AlN thin films were grown epitaxially on the Mo/sapphire substrate with an in-plane relationship of AlN [112¯0]//sapphire [101¯0]. This epitaxial growth was attributed to the highly ordered and oriented Mo electrode layer grown on the sapphire substrate. In contrast, the AlN deposition on the Mo/SiO2/Si substrate under the same conditions caused poorly oriented films with a polycrystalline structure. There coexisted two different low-crystalline phases of Mo (110) and Mo (211) in the Mo layer on the SiO2/Si substrate, which led to the high mosaicity and polycrystalline structure of the AlN thin films.

26

Nutt, S. R., e David J. Smith. "High-resolution TEM of thin-film β-SiC interfaces". Proceedings, annual meeting, Electron Microscopy Society of America 44 (agosto 1986): 408–9. http://dx.doi.org/10.1017/s0424820100143638.

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Silicon carbide is a large band gap semiconductor under development for microelectronic device applications involving high temperatures, high frequencies, and high power. Single crystal thin films of high purity β-SiC can be fabricated by epitaxial CVD onto a <100> silicon wafer substrate. Epitaxial growth is achieved by a two-step process in which the surface of the silicon substrate is first converted to SiC by heating in the presence of hydrocarbon vapors, Despite the large lattice mismatch, this process results in an epitaxial film of β-SiC 10nm in thickness, upon which the SiC crystal is then chemically vapor deposited. Relatively thick (20 microns) crack-free films of SiC can thus be fabricated, although significant problems remain, such as lattice constant and thermal expansivity mismatches, and metallization and passivation of the surface. These reasons have provided the motivation for a detailed examination of interface structures in β-SiC thin films using HRTEM imaging of cross-sectional specimens.

27

Zhang, H., H. L. M. Chang, J. Guo e T. J. Zhang. "Microstructure of epitaxial VO2 thin films deposited on (1120) sapphire by MOCVD". Journal of Materials Research 9, n. 9 (settembre 1994): 2264–71. http://dx.doi.org/10.1557/jmr.1994.2264.

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Epitaxial VO2 thin films grown on (1120) sapphire (α-Al2O3) substrates by MOCVD at 600 °C have been characterized by conventional electron microscopy and high resolution electron microscopy (HREM). Three different epitaxial relationships between the monoclinic VO2 films and sapphire substrates have been found at room temperature: I. (200) [010] monoclinic VO2 ‖ (1120) [0001] sapphire, II. (002) [010] monoclinic VO2 ‖ (1120) [0003] sapphire, and III. (020) [102] monoclinic VO2 ‖ (1120) [0001] sapphire. Expitaxial relationships II and III are equivalent to each other when the film possesses tetragonal structure at the deposition temperature; i.e., they can be described as (010) [100] tetragonal VO2 ‖ (1120) [0001] sapphire and (100) [010] tetragonal VO2 ‖ (1120) [0001] sapphire. HREM image shows that the initial nucleation of the film was dominated by the first orientation relationship, but the film then grew into the grains of the second and the third (equivalent to each other at the deposition temperature) epitaxial relationships. Successive 90°transformation rotational twins around the a-axis are commonly observed in the monoclinic films.

28

Vaidya, K. J., C. Y. Yang, M. DeGraef e F. F. Lange. "Heteroepitaxy of rare-earth hexa-aluminates on sapphire". Journal of Materials Research 9, n. 2 (febbraio 1994): 410–19. http://dx.doi.org/10.1557/jmr.1994.0410.

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We have grown epitaxial thin films of rare-earth hexa-aluminates on basal plane sapphire from liquid precursors. LnAl11O18 (Ln = Gd3+, Nd3+) films form via the reaction of a perovskite intermediate phase and the sapphire substrate according to LnAlO3 + 5Al2O3 = LnAl11O18. Hexa-aluminate thin films with magnetoplumbite (MP) structure grow epitaxially with (0001)mp ‖(0001)s, 〈1120mp‖〈1010〉s orientation relationship. The a-axis of the film is rotated 30°with respect to the substrate. This rotation results in a smaller mismatch (∼1%) between the two oxygen sublattices. Thermodynamic and kinetic arguments pertaining to magnetoplumbite formation for the smaller Gd3+ cation are presented. These epitaxial thin films are likely to have application in higher temperature ion conduction, catalysis, fluorescence, and as laser host.

29

Koo, Junmo, Jae Hyeok Jang e Byeong-Soo Bae. "Preparation and characteristics of seeded epitaxial (Sr,Ba)Nb2O6 optical waveguide thin films using sol-gel method". Journal of Materials Research 16, n. 2 (febbraio 2001): 430–36. http://dx.doi.org/10.1557/jmr.2001.0065.

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Highly c-axis-oriented (Sr,Ba)Nb2O6 (SBN) films were grown on a seeded MgO(100) substrate via sol-gel method. The substrate was preseeded with epitaxial islands of SBN made by breaking up a continuous film into single-crystal islands by pores. Since the number of epitaxial nuclei was increased at the interface between the film and the substrate, the film on a seeded substrate had better highly orientation than that on unseeded substrate. The film having low Sr content exhibited better epitaxial growth because of the distorted unit-cell network and the change of lattice parameters of SBN thin film. For obtaining excellent optical properties, SBN:75 film was prepared on MgO substrate with SBN:25 composition seed layer. Because of low birefringence of refractive indices in the film having high Sr content, the optical scattering loss by the anisotropy of refractive indices was suppressed.

30

Tan, Ming, Wei-Di Liu, Xiao-Lei Shi, Qiang Sun e Zhi-Gang Chen. "Minimization of the electrical contact resistance in thin-film thermoelectric device". Applied Physics Reviews 10, n. 2 (giugno 2023): 021404. http://dx.doi.org/10.1063/5.0141075.

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High electrical contact resistance refrains the performance of thin-film thermoelectric devices at the demonstrative level. Here, an additional Ti contact layer is developed to minimize the electrical contact resistance to ∼4.8 Ω in an as-assembled thin-film device with 50 pairs of p–n junctions. A detailed interface characterization demonstrates that the low electrical contact resistance should be mainly attributed to the partial epitaxial growth of Bi2Te3-based thin-film materials. Correspondingly, the superlow electrical contact resistance facilitates the applicability of the out-of-plane thin-film device and results in an ultrahigh surface output power density of ∼81 μW cm−2 at a low temperature difference of 5 K. This study illustrates the Ti contact layer that strengthens the contact between Cu electrodes and Bi2Te3-based thermoelectric thin films mainly through partial epitaxial growth and contributes to high-performance thin-film thermoelectric devices.

31

Kim, Jin Hyeok, Boram Kim, David Andeen e Fred F. Lange. "Seeded epitaxial growth of ZnO thin films on MgAl2O4 substrates using the chemical solution deposition method". Journal of Materials Research 22, n. 4 (aprile 2007): 943–49. http://dx.doi.org/10.1557/jmr.2007.0109.

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Epitaxial ZnO thin films were grown on (111) MgAl2O4 with a pre-seeded, two-step chemical solution deposition process. Isolated, epitaxial ZnO islands (seeds) were formed on the substrate in the first step by spin coating a very thin layer of the precursor solution and heat-treating to 950 °C/3 h. In the second step, the seeded substrate was coated with another layer of precursor to produce an epitaxial film. The result was compared with the case in which a MgAl2O4 substrate was not seeded. Both the seeded and unseeded ZnO films have out-of-plane and in-plane orientation relationships of , respectively. However, only the seeded ZnO films have very faceted surface morphology without grain boundaries, indicating epitaxy, whereas the unseeded ZnO films have deep grain boundaries indicative of polycrystalline nature. This result shows that the formation of seeds in the first step plays an instrumental role in the formation of an epitaxial ZnO film.

32

Partlow, D. P., e J. Greggi. "Properties and microstructure of thin LiNbO3 films prepared by a sol-gel process". Journal of Materials Research 2, n. 5 (ottobre 1987): 595–605. http://dx.doi.org/10.1557/jmr.1987.0595.

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Thin LiNbO3 films were prepared from polymerized sol-gel precursor solutions having various concentrations and water:alkoxide ratios in an effort to investigate the effects of these and other processing variables on the resultant film properties and microstructure. Films deposted on silicon substrates were mostly amorphous when pyrolyzed at 435°C for 30 min. Randomly oriented polycrystalline films having distinctive microstnietures were produced using longer heating times or higher temperatures. All of the films exhibited low refractive indices due to porosity, which was attributed to the low level of hydrolysis water required to produce stable polymeric precursor solutions. When single-crystal LiNbO4 was used as the substrate, epitaxial growth of the film resulted. This ideal case establishes the feasibility of producing epitaxial films via sol-gel processing. All films were characterized by transmission electron microscopy (TEM) and thin-film x-ray diffraction patterns.

33

M C Ávila, Renan, Roney C da Silva e Rogério J Prado. "Preparation of epitaxial BiFeO3 thin films on Si(001) substrates by pulsed electron deposition". Physics & Astronomy International Journal 7, n. 2 (3 aprile 2023): 77–81. http://dx.doi.org/10.15406/paij.202307.00288.

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To achieve the epitaxial thin films deposition, it is necessary to use properly oriented substrates, with or without buffer layers, matching the lattice parameters of the epitaxial thin film we want to grow. In this work, the deposition of epitaxial Bi2SiO5(200) and BiFeO3(001) thin films on Si(001) substrates by pulsed electron deposition (PED) technique is reported without special substrate preparation. The deposition of epitaxial BSO(200) and T-BFO(001) directly onto Si(001) substrates during a single target deposition process is relevant and presents enormous potential to reduce costs and improve practicality, interface quality and BFO integration efficiency with Si(001) substrates.

34

Herklotz, Andreas, Florina Stefania Rus, Martin M. Koch, Kyle M. Grove, Michael S. Bowen, David P. Cann, Kristin Tippey e Kathrin Dörr. "Epitaxial Stabilization of Perovskite ATeO3 Thin Films". Coatings 13, n. 12 (7 dicembre 2023): 2055. http://dx.doi.org/10.3390/coatings13122055.

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Tellurium oxides of the ATeO3 form typically do not crystallize in perovskite structures. Here, we show that perovskite-like ATeO3 (A = Ca, Sr, Ba) thin films can be grown on perovskite single-crystal substrates via epitaxial stabilization. These films are stable with high optical bandgaps, low dielectric losses, and a high electric breakdown strength. Hysteretic dielectric behavior found in SrTeO3 and BaTeO3 strongly suggests the presence of antiferroelectricity and ferroelectricity, respectively. These properties make perovskite tellurium oxides possibly appealing candidates for thin film coating or insulator materials in advanced microelectronics. Tellurium oxides constitute a largely unexplored class of materials that might show new and interesting functionalities in epitaxial thin-films. Our work encourages new work within this field.

35

Kamiya, T., H. Ohta, M. Kamiya, K. Nomura, K. Ueda, M. Hirano e H. Hosono. "Li-Doped NiO Epitaxial Thin Film with Atomically Flat Surface". Journal of Materials Research 19, n. 3 (marzo 2004): 913–20. http://dx.doi.org/10.1557/jmr.2004.19.3.913.

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Li-doped NiO epitaxial films with high electrical conductivity and atomically flat stepped surfaces were fabricated by a combined technique of pulsed laser deposition and subsequent annealing. It was determined that subsequently annealing at temperatures as low as 600 °C significantly decreased electrical conductivity due to Li evaporation when the film surface was not protected from Li evaporation. To suppress Li evaporation, a yttria-stabilized-zironia plate was used to cover the film surface, which raised the annealing temperature up to 1300 °C while maintaining a high Li concentration and electrical conductivity. Thermally annealing at this temperature also improved crystal quality and formed epitaxial films with atomically flat stepped surfaces. The films were single crystalline at least in observation areas, 10 μm × 10 μm. A reasonably large Hall mobility approximately 0.05 cm2/Vs similar to that reported for bulk single-crystal NiO and a visible-light transmission in excess of 75% were obtained on 120-nm-thick films. Although annealing at higher temperatures such as 1400 °C can further improve the structural and optical properties, the Li concentration in the films was decreased to <3% of the as-deposited film.

36

Patrykiejew, A., e S. Sokolowski. "On the Melting and Disordering of Thin Epitaxial Films". Adsorption Science & Technology 25, n. 7 (settembre 2007): 451–61. http://dx.doi.org/10.1260/0263-6174.25.7.451.

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The disordering of thin films formed on the (100) plane of the face centred cubic (fcc) crystal was studied by the Monte Carlo simulation method. It was shown that the adsorbed films, which order into the (1 × 1) structure in each layer at low temperatures, disorder in a layer-by-layer mode, at least for films with thicknesses of up to 12 layers. It was also demonstrated that, with increasing film thickness, the temperature at which the film disorders depended on the strain resulting from the mismatch between the sizes of the adsorbate atoms and the surface lattice.

37

Komatsu, Keiji, Pineda Marulanda David Alonso, Nozomi Kobayashi, Ikumi Toda, Shigeo Ohshio, Hiroyuki Muramatsu e Hidetoshi Saitoh. "Epitaxial Growth of Magnesia Films on Single Crystalline Magnesia Substrates by Atmospheric-Pressure Chemical Vapor Deposition". Journal of Materials Science Research 5, n. 2 (31 gennaio 2016): 56. http://dx.doi.org/10.5539/jmsr.v5n2p56.

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<p class="1Body">MgO films were epitaxially grown on single crystal MgO substrates by atmospheric-pressure chemical vapor deposition (CVD). Reciprocal lattice mappings and X-ray reflection pole figures were used to evaluate the crystal quality of the synthesized films and their epitaxial relation to their respective substrates. The X-ray diffraction profiles indicated that the substrates were oriented out-of-plane during MgO crystal growth. Subsequent pole figure measurements showed how all the MgO films retained the substrate in-plane orientations by expressing the same pole arrangements. The reciprocal lattice mappings indicated that the whisker film showed a relatively strong streak while the continuous film showed a weak one. Hence, highly crystalline epitaxial MgO thin films were synthesized on single crystal MgO substrates by atmospheric-pressure CVD.</p>

38

Jokerst, N. M. "Integrated Optoelectronics Using Thin Film Epitaxial Liftoff Materials and Devices". Journal of Nonlinear Optical Physics & Materials 06, n. 01 (marzo 1997): 19–48. http://dx.doi.org/10.1142/s0218863597000034.

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The separation of single crystal thin film epitaxial compound semiconductor layers from a lattice matched growth substrate through selective etching, with subsequent bonding of the epitaxial thin film devices onto host substrates, is an emerging tool for multi-material, hybrid integration. Progress to date in this area, presented herein, includes advanced thin film devices, thin film material separation and device integration processing techniques, and thin film material and device integration with host substrates which include silicon circuitry, polymers, glass, and lithium niobate.

39

Chang, H. L. M., T. J. Zhang, H. Zhang, J. Guo, H. K. Kim e D. J. Lam. "Epitaxy, microstructure, and processing-structure relationships of TiO2 thin films grown on sapphire (0001) by MOCVD". Journal of Materials Research 8, n. 10 (ottobre 1993): 2634–43. http://dx.doi.org/10.1557/jmr.1993.2634.

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TiO2 thin films have been deposited on sapphire (0001) substrates under various conditions by metal-organic chemical vapor deposition. The structural properties of the deposited films were characterized by x-ray diffraction and transmission electron microscopy. The important growth parameters were found to be the deposition temperature and the deposition rate. The ranges studied for the two parameters were 400 to 850 °C and 10 to 120 Å/min, respectively. Depending on the growth conditions, most of the deposited films were either single-phase anatase or rutile, or a mixture of the two. These films were all epitaxial, but none of them were single-crystal films. Three distinct epitaxial relationships were observed between the films and the substrates, and, depending on the growth conditions, a deposited film can contain one, two, or all three of them. The fact that the films we obtained, although epitaxial, were never single crystal is explained based on the consideration of the difference in the rotational symmetries of the substrate surface and the film growth plane. We believe that it should be generally true that, in heteroepitaxial growth, a true single-crystal film can never be obtained as long as the point symmetry group of the substrate surface is not a subgroup of that of the film growth plane.

40

Kaul, Andrey R., Roy R. Nygaard, Vadim Yu Ratovskiy e Alexander L. Vasiliev. "TSF-MOCVD – a novel technique for chemical vapour deposition on oxide thin films and layered heterostructures". Kondensirovannye sredy i mezhfaznye granitsy = Condensed Matter and Interphases 23, n. 3 (17 agosto 2021): 396–405. http://dx.doi.org/10.17308/kcmf.2021.23/3531.

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A new principle for supplying volatile precursors to MOCVD gas-phase chemical deposition systems is proposed, based on a two-stage evaporation of an organic solution of precursors from a soaked cotton thread, which passes sequentially through the zones of evaporation of the solvent and precursors. The technological capabilities of TSF-MOCVD (Thread-Solution Feed MOCVD) are demonstrated based on examples of obtaining thin epitaxial films of СеО2, h-LuFeO3 and thin-film heterostructures β-Fe2O3/h-LuFeO3. The results of studying the obtained films by X-ray diffraction, energy dispersive X-rayanalysis, and high- and low-resolution transmission microscopy are presented. Using the TSF module, one can finely vary the crystallisation conditions, obtaining coatings of the required degree of crystallinity, as evidenced by the obtained dependences of the integral width of the h-LuFeO3 reflection on the film growth rate. Based on the TEM and XRD data, it was concluded that β-Fe2O3 grows epitaxially over the h-LuFeO3 layer. Thus, using TSF-MOCVD, one can flexibly change the composition of layered heterostructures and obtain highly crystalline epitaxial films with a clear interface in a continuous deposition process

41

McIntyre, Paul C., e Michael J. Cima. "Heteroepitaxial growth of chemically derived ex situ Ba2YCu3O7−x thin films". Journal of Materials Research 9, n. 9 (settembre 1994): 2219–30. http://dx.doi.org/10.1557/jmr.1994.2219.

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Heteroepitaxial growth of Ba2YCu3O7−x (BYC) thin films prepared by postdeposition annealing on (001) LaAlO3 was characterized by TEM and x-ray diffraction studies of specimens rapidly cooled from various points in the growth heat treatment. Heteroepitaxial nucleation of BYC occurred between 720 and 770 °C during heating at 25 °C/min to the annealing temperature of 830 °C. The c-axis normal BYC rapidly coalesced into a continuous film with nearly complete coverage of the substrate surface after growth of a film of several unit cells thickness. The experimental results were not consistent with purely solid phase heteroepitaxial nucleation and growth or epitaxial grain growth, mechanisms for microstructural evolution of other chemically derived epitaxial oxide thin films. The nature of the transformation and the microstructure of the final superconducting films were consistent, instead, with growth of epitaxial BYC from a liquid phase that is present transiently during the anneal. This hypothesis was supported by thermal analysis results obtained from the precursor material of which the films are composed prior to transformation to BYC.

42

Trinkler, Laima, Dajin Dai, Liuwen Chang, Mitch Ming-Chi Chou, Tzu-Ying Wu, Jevgenijs Gabrusenoks, Dace Nilova, Rihards Ruska, Baiba Berzina e Ramunas Nedzinskas. "Luminescence Properties of Epitaxial Cu2O Thin Films Electrodeposited on Metallic Substrates and Cu2O Single Crystals". Materials 16, n. 12 (13 giugno 2023): 4349. http://dx.doi.org/10.3390/ma16124349.

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The luminescent properties of epitaxial Cu2O thin films were studied in 10–300 K temperature range and compared with the luminescent properties of Cu2O single crystals. Cu2O thin films were deposited epitaxially via the electrodeposition method on either Cu or Ag substrates at different processing parameters, which determined the epitaxial orientation relationships. Cu2O (100) and (111) single crystal samples were cut from a crystal rod grown using the floating zone method. Luminescence spectra of thin films contain the same emission bands as single crystals around 720, 810 and 910 nm, characterizing VO2+, VO+ and VCu defects, correspondingly. Additional emission bands, whose origin is under discussion, are observed around 650–680 nm, while the exciton features are negligibly small. The relative mutual contribution of the emission bands varies depending on the thin film sample. The existence of the domains of crystallites with different orientations determines the polarization of luminescence. The PL of both Cu2O thin films and single crystals is characterized by negative thermal quenching in the low-temperature region; the reason of this phenomenon is discussed.

43

WANG, XINCHANG, ZHIZHEN YE, JUNHUI HE, JINGYUN HUANG e BINGHUI ZHAO. "GROWTH AND CHARACTERIZATION OF C-ORIENTED LiNbO3 THIN FILMS ON Si (100) BY PLD". International Journal of Modern Physics B 16, n. 28n29 (20 novembre 2002): 4343–46. http://dx.doi.org/10.1142/s0217979202015406.

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Lithium niobate ( LiNbO 3) thin film is an important material for optical waveguide. Recently, particular attention has been paid to the application of LiNbO 3 (LN) thin films. To develop and fabricate integrated optical devices, the growth of thin LN epitaxial films onto silicon substrate is of great importance and particularly attractive. In this paper, LN thin film was grown by pulsed laser deposition (PLD). Stoichiometric LN ceramic is used as a target. Amorphous SiO 2 buffer layer was coated on Si (100) wafer by in-situ themal oxidation before the deposition. The optimized condition of growing LN film on Si (100) by PLD is found: O 2 pressure 30 Pa, substrate temperature 600°C. Only (006) reflection of LN was observed besides the (002) reflection of silicon substrate from XRD pattern. The FWHM (~0.21°) of (006) reflection peak is much narrower than the value reported by Lee [1]. The results of XRD measurement indicate that the LN film was epitaxially grown along the c-axis. Transmission electron microcopy (TEM) patterns confirm that the film has superior crystalline quality. The optical waveguiding properties of the films were demonstrated by a prism coupler method. Fully c-oriented thin film could be grown on silicon substrate by PLD without the buffer layer and the induced electric field.

44

Orna, Julia, Luis Morellón, Pedro Algarabel, José M. De Teresa, Amalio Fernández-Pacheco, Gala Simón, Cesar Magen, José A. Pardo e M. Ricardo Ibarra. "Fe₃O₄ Epitaxial Thin Films and Heterostructures: Magnetotransport and Magnetic Properties". Advances in Science and Technology 67 (ottobre 2010): 82–91. http://dx.doi.org/10.4028/www.scientific.net/ast.67.82.

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In this article, we review our recent research on Fe3O4 epitaxial thin films and Fe3O4/MgO/Fe epitaxial heterostructures. More specifically, we report on the magnetotransport properties of Fe3O4 epitaxial films in a wide range of film thicknesses and temperatures, focusing on the anomalous, planar and ordinary Hall effects. We also summarize our insight on the origin of the enhanced magnetic moment found in ultra-thin magnetite films (thickness t < 5 nm). Finally, our work on the growth, and structural and magnetic characterization of heteroepitaxial Fe3O4/MgO/Fe trilayers is presented.

45

Krakow, W., N. M. Rivera, R. A. Roy, R. S. Ruoff e J. J. Cuomo. "Epitaxial growth of C60 thin films on mica". Journal of Materials Research 7, n. 4 (aprile 1992): 784–87. http://dx.doi.org/10.1557/jmr.1992.0784.

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Single crystal films of C60 of different thickness values have been deposited on mica substrates by resistance evaporation. Electron diffraction and high resolution microscopy have been used to assess the orientational ordering and the nature of the defects present in these face-centered cubic films which exhibit a 〈111〉 direction normal to the film surface.

46

Thompson, Carl V. "The Origins of Epitaxial Orientations in thin Films". MRS Proceedings 280 (1992). http://dx.doi.org/10.1557/proc-280-307.

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ABSTRACTWhen a continuous film is deposited on a planar, single crystal substrate, there is usually a single set of relative film-substrate orientations for which the free energy of the film-substrate interface is minimized. It is often assumed that epitaxial films have adopted the orientation which minimizes this energy. However, this is not necessarily the case. Orientation selection is also constrained by minimization of the energy of the/ree surface of a film, as well as by minimization of the strain energy. In systems in which films grow by an island mechanism, epitaxial orientations can be established during or after nucleation, and can change before or after formation of a continuous film. Interfacial and surface energy minimization is constrained differently for islands and films. Epitaxial grain growth is a process which occurs in continuous films, in which epitaxially-aligned, energy-minimizing grains grow at the expense of other grains. Recent experiments on epitaxial grain growth in polycrystalline Ag films on single crystal Ni is discussed to illustrate, the affects of surface, interface, and strain energy minimization on epitaxial orientation selection.

47

Kolluri, Kedarnath, Luis A. Zepeda-Ruiz, Cheruvu S. Murthy e Dimitrios Maroudas. "Strain Relaxation in Si1-xGex Thin Films on Si (100) Substrates: Modeling and Comparisons with Experiments". MRS Proceedings 875 (2005). http://dx.doi.org/10.1557/proc-875-o4.21.

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AbstractStrained semiconductor thin films grown epitaxially on semiconductor substrates of different composition, such as Si1-xGex/Si, are becoming increasingly important in modern microelectronic technologies. In this paper, we report a hierarchical computational approach for analysis of dislocation formation, glide motion, multiplication, and annihilation in Si1-xGex epitaxial thin films on Si substrates. Specifically, a condition is developed for determining the critical film thickness with respect to misfit dislocation generation as a function of overall film composition, film compositional grading, and (compliant) substrate thickness. In addition, the kinetics of strain relaxation in the epitaxial film during growth or thermal annealing (including post-implantation annealing) is analyzed using a properly parameterized dislocation mean-field theoretical model, which describes plastic deformation dynamics due to threading dislocation propagation. The theoretical results for Si1-xGex epitaxial thin films grown on Si (100) substrates are compared with experimental measurements and are used to discuss film growth and thermal processing protocols toward optimizing the mechanical response of the epitaxial film.

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Hosaka, Makoto, Yasuyuki Akita, Yuki Sugimoto, Yushi Kato, Yusaburo Ono, Akifumi Matsuda, Koji Koyama e Mamoru Yoshimoto. "Low-Temperature Selective Growth of Heteroepitaxial α-Al2O3 Thin Films on a NiO Layer by the Electron-Beam Assisted PLD Process". MRS Proceedings 1150 (2008). http://dx.doi.org/10.1557/proc-1150-rr04-04.

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AbstractSelective heteroepitaxial growth of α-Al2O3 thin films on a NiO layer was investigated using an electron-beam assisted pulsed laser deposition process. The epitaxial NiO layer was grown on an ultrasmooth sapphire (α-Al2O3 single crystal) (0001) substrate. The α-Al2O3 thin film could be grown epitaxially only in the electron-beam irradiated region of the epitaxial NiO layer at 300°C, while the amorphous Al2O3 film was grown in the non-irradiated region. The homoepitaxial growth of α-Al2O3 thin films could not be attained on the sapphire (0001) substrate at 300°C. This indicates that the electron-beam irradiation enhances heteroepitaxial growth of the α-Al2O3 thin films on the NiO layer at 300°C. When we annealed the epitaxial Al2O3/NiO bilayer film at 350°C in a hydrogen atmosphere, we could reduce only the NiO layer to an epitaxial Ni metal layer, allowing the fabrication of epitaxial Al2O3/Ni (insulator/metal structure) films. The fabricated Al2O3/Ni bilayer films exhibited a very smooth surface.

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Hattori, Y., A. Mizoguchi, Y. Ogaki e A. Nishimtjra. "Epitaxial Growth of Organic Nonlinear Optical Materials". MRS Proceedings 247 (1992). http://dx.doi.org/10.1557/proc-247-235.

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ABSTRACTAs an orientation control technique for organic materials, epitaxial growth on crystal substrates was studied for DBNA, a derivative of p-nitroani1 ine, and polydiacetylene(PDA)-3BCMU using Vacuum Deposition and Molecular Beam Epitaxy(MBE).The thin film of DBNA was epitaxially grown on a KCl(001) surface by Vacuum Deposition. Molecular orientation to the substrate (parallel or normal) was controlled by MBE. PDA-3BCMTJ thin films were prepared by UV light irradiation of DA-3BCMU(monomer) thin films which were epitaxially grown on a KCl(001) surface, x(3) values of this oriented thin film were larger than those of unoriented spin-casted thin film.

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Kawai, Masanori, Daisuke Kan, Seiichi Isojima, Hiroki Kurata, Seiji Isoda, Shigeru Kimura, Osami Sakata e Yuichi Shimakawa. "Deposition Rate Effect on Critical Thickness of BaTiO3 Epitaxial Thin Film Grown on SrTiO3 (001)". MRS Proceedings 1034 (2007). http://dx.doi.org/10.1557/proc-1034-k10-04.

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AbstractBaTiO3/SrTiO3(001) epitaxial thin films were prepared at various growth rates by pulsed laser deposition, and their heterostructures were evaluated by synchrotron x-ray diffraction measurements and cross-sectional scanning transmission electron microscopy observations. In a film grown at a low deposition rate (0.01 nm/s), misfit dislocations are found near the interface and a fully relaxed BaTiO3 thin film grows epitaxially on the substrate. On the other hand, a film grown at a high deposition rate (0.04 nm/s) consists of strained and relaxed BaTiO3 lattices. Our results showed that the critical thickness of BaTiO3/SrTiO3(001) epitaxial thin films can be controlled by the deposition rate and that the critical thickness increases with increasing the deposition rate, and by adjusting the deposition rate we were able to prepare epitaxial thin films consisting of fully strained BaTiO3, partially strained BaTiO3 or fully relaxed BaTiO3. We have also achieved the growth controlling of BaTiO3 thin films on SrTiO3(001) substrates with SrRuO3 bottom electrode layer.

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