In-plane Film Research Articles

Morphology‐property relationships in oriented PET films: A role of in‐plane crystalline orientation distribution on the film properties

AbstractThe role of in‐plane crystalline, amorphous, and overall molecular orientation on various properties in the plane of the films was investigated using a variety of techniques. It is shown that for a fixed value of crystallinity the in‐plane crystalline orientation and the nature of the constraint imposed by the crystallites on the molecules play an important role in obtaining isotropic in‐plane expansion or shrinkage properties. Achievement of in‐plane isotropic tensile strength and elongation at the break are found to depend entirely upon an isotropic distribution of the amorphous orientation; the orientation of crystallites plays no detectable role. Furthermore, the deformation mechanisms of sequential and simultaneous biaxial stretching processes have been investigated and compared. The simulteneous stretching process is considered to be a more controlled film‐fabricating method compared to sequential stretching in achieving balanced, in‐plane film properties. © 1993 John Wiley & Sons, Inc.

Annealing studies of magnetron-sputtered CoCr thin films

The microstructure and magnetic properties of annealed CoCr thin films of various thicknesses, deposited on glass substrates, were examined. In general, little grain growth upon annealing was observed. Low-angle grain boundaries, present in as-sputtered films of thickness ⩽50 nm, were absent in annealed films. This occurs simultaneously with a decrease in the measured electrical resistivity. A reduction in the in-plane film stress occurs with annealing, correspondingly the experimentally measured anisotropy field values change markedly. A noticeable feature of the microstructure is the appearance of Cr-rich regions in annealed films 50 nm thick and above. These regions are thought to account for the observed increases in the saturation magnetization and coercivity with annealing time.

Preparation and characterization of c-axis in-plane YBa/sub 2/Cu/sub 3/O/sub 7/ thin films and YBCO/PrBCO superlattices by high pressure sputtering

Epitaxial YBa/sub 2/Cu/sub 3/O/sub 7/ c-axis in-plane thin films and YBCO/PrBCO superlattices have been grown on single-crystal [100] and [110] SrTiO/sub 3/ substrates by high-pressure DC sputtering. The orientation of the deposited films is a function of the deposition temperature, T/sub s/. Preliminary studies of the dissipative behavior of the flux line system in the mixed state of YBCO thin films on [110] SrTiO/sub 3/ substrates were performed. Dissipation processes in both Lorentz force free and Lorentz force configurations are discussed in terms of flux dynamics under the influence of the strong pinning potential intrinsic to the layered structure. Preliminary results for a modulated structure composed of layers of YBCO and insulating PrBCO in a-axis orientation and for the first time [110]-oriented YBCO/PrBCO superlattices are presented. >

Theory for the first-order spin-wave instability threshold in ferromagnetic insulating thin films

A theory for the first-order Suhl and the parallel pumping instability in thin films is presented. Significant differences for the critical microwave field and wave vector to former calculations occur, which discuss the problem in terms of bulk spin-waves neglecting boundary conditions. A coupling matrixCkk′ is introduced, which describes the couplings between the modes and the driving microwave field. For bulk standing spin-wavesCkk′ is always diagonal. For the true discrete standing modes of a thin filmCkk′ changes only in case of 1. Suhl instability and if the wavevector has a non vanishing component perpendicular to the film plane. Here the diagonal bulk couplings have to be replaced in part by off diagonal terms, describing couplings between modes, which perpendicular wave vector componentk⊥ differs byπ/d (d=film thickness). The decisive quantity, which decides if the finite thickness of the film is of importance or if the film can be treated as a bulk system, is the frequency difference δωk of the coupled modes. For δωk much smaller than the spin-wave damping ηk the bulk approximation is correct. For\(\delta \omega _k > > \eta _k \) two experimental situations for 1. Suhl instability are discussed: For a perpendicular to the film plane magnetized film the critical microwave field is by π/2 bigger than in the bulk case. In an in-plane magnetized film the critical spin-waves propagate always in the film plane, as only hereCkk′ remains identical to the bulk case.

Improvement of Jc-B characteristics in biaxially aligned Y-Ba-Cu-O thin films on metallic substrate

Abstract Biaxially aligned (triaxially aligned) YSZ thin films were formed on polycrystalline substrates by ionbeam assisted deposition (IBAD). The biaxial aligning of YSZ was much affected by the incident angle of the assisting ion-beam toward the substrate. In-plane aligned YBCO thin films were deposited by laser ablation on polycrystalline substrates, Hastelloy alloy, with biaxially aligned YSZ thin films as the buffer layers. Jc-B characteristics of these YBCO thin films were improved in one order of magnitude, compared with ones buffered with conventionally sputtered YSZ, and high Jc values of 10 5 A/cm 2 (77K, OT) range stable for many times were obtained. The small mis-orientation angles at grain boundaries of in-plane aligned YBCO thin film along a- and b-axes were observed by TEM.

The growth, structural and optical characterization of large area, single crystalline thin films of 3-nitroaniline (mNA)

The classical organic non-linear optical material 3-nitroaniline (mNA) has been used as a model compound to study the growth of such materials in thin, single crystalline films. Using the excellent melt stability of mNA, we have grown from the melt phase (under ideal conditions) large area (1 × 6 cm 2 ) films which vary in thickness from 5–20 μm. The use of the Laue X-ray technique has allowed the identification of the in-plane film orientation to be carried out. The high structural perfection of the films was defined using glancing angle X-ray topography. The optical characterization of such films, using a Maker fringe experiment, has allowed a value for the d 31 coefficient to be measured which compares favourably with similar coefficients defined for bulk single crystals of high optical and structural quality.

斜め入射光による面内磁化Ｂｉ‐ＹＩＧ薄膜の読み出し特性

Since in-plane garnet films have no components of magnetization with respect to vertically incident lights, no magneto-optical effects on the light are observed. We supposed that when a Bi-YIG film was positioned obliquely to the incident light, the plane of polarization was rotated owing to the magnetooptical effect, because some component of magnetization with respect to the light path appeared. An in-plane Bi-YIG film was prepared on a Corning # 0317 glass substrate by rf sputtering, and was then magnetized in a magnetic field of 2 KOe. The apparatus for detecting Faraday rotation consisted of a polarization microscope and alight source. On the stage of the polarization microscope, the plane of the Bi-YIG film was tilted at 45°to the stage plane. The apparatus was used to obtain contrast images caused by the remanent magnetization of the in-plane Bi-YIG film. This result indicates that in-plane magneto-optical films can be applied to display devices.

Evolution of microstructure and magnetic properties in magnetron-sputtered CoCr thin films

The microstructure and magnetic-structure development in magnetron-sputtered Co-22at%Cr thin films deposited on amorphous substrates has been examined systematically and in detail. It has been found that the initial deposit is amorphous up to a thickness of ≈5 nm. By 10 nm thickness, a polycrystalline highly hcp c-axis textured (out of the film plane) microstructure is observed. At 50 nm thickness, a distinct columnar morphology has developed. A distinct subgrain structure was also observed in the thinner films (10–50 nm). The magnetization is initially in-plane and retains in-plane components up to a thickness of ≈ 50 nm, after which it is predominantly out-of-plane. The effects of in-plane film stress are reflected in the effective anisotropy field and are most evident in the thinner films, where the stress is highest. The thinnest (10 nm) films display in-plane 180° domain walls while thicker (50 nm) films exhibit out-of-plane “dot”-type domain structures. The “dot” domains were observed even in films that had not yet developed a columnar morphology. Intermediate-thickness films show a “feather-like” contrast, indicating that both in- and out-of-plane magnetization components are present. Intrinsic film stress was found to play a major role in determining the preferred magnetization direction and, thus, the resulting magnetic domain configurations.

Growth mechanisms and properties of 90 degrees grain boundaries in YBa2Cu3O7 thin films.

The transport properties of three types of 90\ifmmode^\circ\else\textdegree\fi{} grain boundaries of (103) oriented ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ (YBCO) thin films grown epitaxially on (101) ${\mathrm{SrTiO}}_{3}$ and (101) ${\mathrm{LaAlO}}_{3}$ substrates in situ by 90\ifmmode^\circ\else\textdegree\fi{} off-axis sputtering are compared. A simple description of the in-plane crystallographic film orientation is given by substrate [010]\ensuremath{\parallel}YBCO[010] and substrate [1\ifmmode\bar\else\textasciimacron\fi{}01]\ensuremath{\parallel}YBCO 〈301〉. A domain structure exists with the ${\mathrm{CuO}}_{2}$ planes oriented at \ifmmode\pm\else\textpm\fi{}45\ifmmode^\circ\else\textdegree\fi{} to the substrate surface (i.e., parallel to the substrate [010] direction). Therefore, specific sets of 90\ifmmode^\circ\else\textdegree\fi{} grain boundaries are observed in both principal in-plane directions. The normal-state conductivity and the critical current density of these films along the YBCO [010] direction are as high as the best quality c-axis films, which have no high-angle grain boundaries. The normal-state conductivity and critical current density along the 〈301〉 direction are much lower than in the [010] direction. However, the normalized magnetic-field dependence of ${\mathit{J}}_{\mathit{c}}$ for both those directions is similar and shows no evidence of weak link behavior. These results have important implications for understanding the behavior of step-edge Josephson junctions. The anisotropic transport behavior in the normal and superconducting state is explained by the microstructure and a simple transport model.

Structural and electrical characterization of YBa2Cu3O7−x thin films grown on different substrates

Abstract X-ray diffraction analyses using symmetrical and asymmetrical reflections were performed on YBa 2 Cu 3 O 7− x films grown in situ by pulsed laser deposition. Monocrystalline (100) oriented SrTiO 3 , MgO and YSZ were used as substrates. The measurements allowed the calculation of the film lattice parameters and the determination of the film-substrate epitaxial relationships. The in-plane and out-plane film textures were also studied. The critical current density between 17 K and 87 K was measured in narrow strips patterned by a direct writing laser system. A comparative discussion of the results obtained for the transport properties and the structural characteristics was carried out for films grown on MgO.

Orientation control of YBa2Cu3O7 thin films on MgO for epitaxial junctions

A low-temperature argon ion milling process has been used to induce growth of c-oriented YBa2Cu3O7 on (001) MgO substrates with the in-plane film axes rotated 45° with respect to those of the substrate, and with respect to those of films grown on untreated regions of the substrate. This process is compatible with standard photolithographic processing, and has been used to produce defined areas of the two orientations on the same substrate. Josephson junctions and dc SQUIDs have been fabricated using the resulting grain boundaries.

Magnetic properties of magnetron sputtered Co-Cr thin films

The magnetic properties of magnetron sputtered Co-22 at.% Cr films of various thickness deposited on glass have been examined, with particular attention to the various contributions to the film anisotropy. The magnetization is initially in-plane and retains in-plane components up to a thickness of approximately 50 nm, after which it is predominantly out-of-plane. The effects of in-plane film stress are reflected in the effective anisotropy field and are most evident in the thinner films, where the stress is highest. The in-plane coercivity values appear to be related to the presence of definite microstructural features, which can act as obstacles to domain wall motion. The out-of-plane coercivity is more anisotropy dependent, suggesting that rotation may be involved. These and other results are discussed.

X-ray characterization of in-plane ordering in YBa2Cu3O7−x thin films using a standard Weissenberg camera

We have used a standard Weissenberg camera in the oscillating mode to characterize the in-plane structure of YBa2Cu3O7 thin films. We find that for films optimally grown on (100) MgO or (100) SrTiO3 substrates, the in-plane film axes are aligned parallel to the substrate axes. This is true both for solely c-axis oriented films (perpendicular to the film plane) and for mixed a- and c-axis oriented films. For a film grown on (110) SrTiO3, we have established that the film orientation perpendicular to the film plane is solely (103) and not (110) or a mixture of the two. In addition the in-plane film axes are colinear to the substrate axes.

Stress and Microstructure in Lpcvd Polycrystalline Silicon Films: Experimental Results and Closed Form Modeling of Stresses

ABSTRACTCharacterization of undoped polycrystalline silicon films indicates that correlations exist between stress and microstructure. Films of thickness between 0.5–3.6 μm were deposited onto SiO2-covered single crystal silicon wafers between 605 and 700°C using low pressure chemical vapor deposition (LPCVD). The average in-plane film stress and the stress gradient through the film thickness were determined from wafer curvature measurements, and film microstructure was studied with cross-sectional TEM. Films deposited near 605°C exhibit overall tensile stresses that result from an amorphous to crystalline phase change. At deposition temperatures exceeding 630°C, a columnar grain structure evolves out of a transition region of small grains at the SiO2 interface. The columnar films are compressive, with the source of compression linked to the region of small grains. Stress is modeled using a closed form solution ihat considers a linearly elastic contracting ellipsoidal inclusion near the surface of a half space. Several applications of the stress model are discussed.

Rf-diode sputtered Permalloy film

Permalloy films were deposited by rf-diode sputtering on silicon and glass substrates. The in-plane film stress was measured as a function of film thickness. The cause of stress changes with film thickness is discussed. The deposition rate and the in-plane stress have been correlated with various process parameters, such as rf power, argon pressure, and substrate bias. A regression analysis yields an excellent fit to the experimental data. The in-plane stress in the film was measured using the wafer-bending method and the x-ray method. The stress of Permalloy films on silicon wafer can be either compressive or tensile, depending on the deposition parameters. The stress increases with increased deposition rate. Stress-free films on silicon can be obtained for a deposition rate of about 7.5 nm/min. The films have good magnetic properties when deposited in these conditions.

Growth Characteristics of Co-Cr Thin Films for Magnetic Recording

AbstractThe growth characteristics of magnetron sputtered Co-22%Cr thin films on amorphous glass or carbon substrates have been investigated utilizing transmission electron microscopy,. X-ray diffraction, electrical resisivity and in-plane stress measurements. Results indicate that the initial deposit is “amorphous”, but that isolated islands of small crystallites form before the film reaches 5nm film thickness. By 10nm, well oriented grains with hcp c axis perpendicular to the film plane develop, and by 50nm, a twinned columnar microstructure is evident. As this occurs, the in-plane film stress becomes constant. Also, we have observed a distinct subgrain structure in the thinner films (10–50 nm), and this is reflected in the electrical resistivity. This cannot be accounted for by an “evolutionary selection” growth scenario, but must be related to the low surface mobility of adatoms at these low substrate deposition temperatures.

Analysis of medium-double layer garnet film interaction in a parallel high density magnetooptic read head

Multitrack readout using the magnetooptic Faraday effect in garnet films has improved the density of information. The garnet films are Bi-substituted YIG samples that can resolve down to about 2 mu m/sup 2/. A double garnet layer has been used to improve the interaction between the garnet and the magnetic tape. The first layer has its magnetization parallel to the plane of the film, while the outer layer's is perpendicular. The contribution of the first layer allows better guiding of the field lines of the magnetic tape. This can be understood in terms of the mirror effect, whereby the system consisting of the tape and the double layer is equivalent to a single layer (perpendicular) twice as thick that is coupled twice to the magnetic tape. It is found that the best configuration for the in-plane film is a flux-closure-domain configuration, because its anisotropy constant is much lower than that of the perpendicular layer.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Gd-Base Amorphous Magneto-Optical Films with Large Kerr Rotations

Gd-Fe-Co system has a high Kerr rotation under a forced magnetic field, but this is an in-plane magnetized film. We attempted to produce a perpendicularly magnetized film by adding Tb, Dy or Ho to GdFeCo with high Kerr rotation. Measurement of the variation with temperature of ? K for the samples with Tb, Dy and Ho substituted showed that ? K was higher for all of them than for the Tb-Fe-Co over the whole temperature range, indicating that they have a sufficiently large ? K value and that high playback output can be obtained. When static recording was performed on Gd-Dy-Fe-Co perpendicularly magnetized film, excellent recording bit formations of diameter 1.3 ?m were obtained.

Galvanomagnetic Effects in Sm-Co Amorphous Magnetic Films

The galvanomagnetic effects of SmCo amorphous magnetic films are discussed. In films with in-plane magnetization, resistivity rose gradually with the Sm concentration, while the Hall resistivity, Hall sensitivity, and Hall voltage peaked around 15 atm% Sm and gradually declined. In perpendicular magnetization films, both the Hall resistivity and Hall sensitivity decreased as the Sm content increased. In both perpendicular and in-plane magnetization film, the Kerr rotation angle decreased as the Sm concentration increased.

On the coercivity of sputtered CoCr films (abstract)

CoCr films with the nominal composition of 20 at. % Cr were rf sputtered onto a glass substrate as a function of both substrate temperature (Ts) and argon pressure (PAr). By controlling the process parameters, both positive effective and in-plane anisotropy films can be obtained. The angular variation of the coercivities of these films (which serves as a test of the possible coercivity mechanisms) has been measured.1 We found that no unique correspondence exists between our experimental data and Wuori’s theoretical models of the reversal mechanism.2 By changing the substrate temperature, a family of monotonically decreasing, angular-dependent coercivity curves are obtained. The perpendicular film made at low Ts and PAr shows a slowly decreasing dependence of the coercivity as a function of the field angle. Furthermore, the easy-axis hysteresis loop displays a reentrant magnetization effect. The complexity of the magnetization reversal process is attributed to nonhomogeneous crystal structure. (All of these films exhibit evidence of a soft magnetic underlayer.) Ferromagnetic resonance (FMR) spectra measured at 9.8 and 35.2 GHz show multiple resonance structures. The anisotropy constant of the films become increasingly more negative with increasing argon pressure and/or substrate temperature. These results are consistent with bulk magnetic measurements made by vibrating sample magnetometry and microstructural observations using transmission electron microscopy.3 Details of the structural characterization by FMR and its implication on the coercivity mechanism will be presented.