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1.
Inverted cylindrical magnetron sputtering (ICM) is a reliable and reproducible method for the production of HTSC thin films. This allows systematic studies of film growth as a function of various deposition parameters, including film thickness, substrate material, or buffer layers. After describing in some detail the special demands on sputtering devices for HTSC thin film growth, we report the growth conditions and growth quality of 1–2–3 films of different orientation on substrates such as SrTiO3 and MgO. Furthermore, we report on the growth of buffer layers of YSZ onR-plane sapphire. Epitaxial GdBa2Cu3O7 films grown on these buffer layers showed critical current densities of 3×106 A/cm2 at 77 K and a zero resistance transition temperature of 92.5 K. 相似文献
2.
The epitaxial strain can modify the physical properties of complex oxide thin films considerably. The strain effect is expected to be less pronounced for relatively thick films and the physical properties should resemble to the bulk material. However, it has been recently observed that the electronic and magnetic properties of La0.5Ca0.5MnO3 thin films deposited on (111) SrTiO3 substrates thicker than a threshold value differ considerably from the bulk material. This observation is a hint for some interesting microstructural features in these films. In the present study, the microstructure of La0.5Ca0.5MnO3 thin films on (111) SrTiO3 substrates is investigated by X-ray diffraction and high resolution transmission electron microscopy. 相似文献
3.
Dielectric SrTiO3 thin films were deposited on LaAlO3 and Si substrates using laser molecular beam epitaxy. The correlations between the deposition parameters of SrTiO3 thin films, their structural characteristics, and dielectric properties were studied. The conditions for achieving epitaxial SrTiO3 thin films were found to be limited to deposition conditions such as deposition temperature. We show that the SrTiO3 films with single (110) orientation can be grown directly on Si substrates. The nature of epitaxial growth and interfacial structures of the grown films were examined by various techniques, such as Laue diffraction and X-ray photoelectron spectroscopy. The SrTiO3/Si interface was found to be epitaxially crystallized without any SiO2 layer. Furthermore, we have measured dielectric properties of the grown SrTiO3 multilayer suitable for tunable microwave device. A large tunability of 74.7%, comparable to that of SrTiO3 single-crystal, was observed at cryogenic temperatures. Such STO thin films will be very promising for the development of microelectronic device applications. 相似文献
4.
L. P. Guo G. R. Liu W. L. Zhou R. H. Yi L. Li Y. Yang J. Q. Li Y. Q. Zhou Z. X. Zhao 《Journal of Superconductivity》1995,8(1):155-161
Detailed transmission electron microscopic study has been carried out on heteroepitaxial YBa2Cu3O7/SrTiO3/YBa2Cu3O7 trilayer thin films grown on (100)SrTiO3 substrates prepared by DC and RF magnetron sputtering. The microstructural results showed the existence of somea-axis-oriented YBCO grains 20–90 nm wide in thec-axis-oriented YBCO matrix. Some of thea-axis grains in the lower YBCO thin film layer have protruded into the above SrTiO3 layer, which may cause short circuit between the two YBCO superconducting layers. This is unsuitable for the application of trilayer thin films for microelectronic devices. The defects on the surface of the substrates would also influence the growth quality of the YBCO thin films. 相似文献
5.
F. M. Pontes E. J. H. Lee E. R. Leite E. Longo J. A. Varela 《Journal of Materials Science》2000,35(19):4783-4787
SrTiO3 thin films were prepared by the polymeric precursor method and deposited by spin-coating onto Pt/Ti/SiO2/Si(100) substrates. The spin-coated films heat treated at 700°C were crack-free, dense, and homogeneous. Microstructural and morphological evaluations were followed by grazing incident X-ray, scanning electron microscopy and atomic force microscopy. Dielectric studies indicated a dielectric constant of about 475, which is higher than that of ceramic SrTiO3, and a factor dissipation of about 0.050 at 100 kHz. SrTiO3 thin films were found to have paraelectric properties with C-V characteristics. 相似文献
6.
Hwisim Hwang Yasutomo Uetsuji Tsutao Katayama Eiji Nakamachi 《Journal of Materials Science》2011,46(5):1380-1387
A three-scale analysis of crystal growth process is newly proposed based on the first-principles calculation and on the finite
element analysis in order to generate a new biocompatible piezoelectric thin film. Crystal growth process of lead-free BaTiO3 thin films was designed and experimentally generated on SrTiO3(100), (110), (111), and MgO(100) substrates using the radio-frequency magnetron sputtering method. Crystal structures of
BaTiO3 were measured by X-ray diffraction (XRD) θ/2θ scan. We used Pt for the electrode and measured piezoelectric strain constants d
33 using the ferroelectric measurement system. As a result, analytical crystal orientation fractions on SrTiO3(110) and (111) substrates had good quantitative agreement with experimental ones, and ones on SrTiO3(100) and MgO(100) substrates corresponded with these experimental crystal structures. Furthermore, analytically determined
piezoelectric strain constants d
33 qualitatively showed a good agreement with experimental ones. Especially, for SrTiO3(100) and MgO(100) substrates, the differences of d
33 depending on orientation fractions were analyzed by the three-scale simulation accurately. Consequently, it is confirmed
that the three-scale analysis is a useful simulation tool to design new biocompatible piezoelectric thin films. 相似文献
7.
J. L. Li Y. Rong Li J. Zhu Y. Zhang F. Yang W. Fei 《Journal of Materials Science》2006,41(12):3761-3766
A series of experiments of strain modulations in heterostructures of SrTiO3/LaAlO3 and LaAlO3/SrTiO3 perovskite thin films fabricated by laser molecular beam epitaxy (L-MBE) were performed to study the effect of the compressive
stress and tensile stress on the growth and microstructure of the films. The growth process of the films was in-situ monitored by reflective high-energy electron diffraction (RHEED). The morphology of the films was studied by ex-situ atomic force microscopy (AFM). We demonstrated that the compressive stress-induced self-organized SrTiO3 films deposited on LaAlO3 (100) single crystal substrates exhibited a periodic well-ordered ripple-shaped structure, forming a unique nanopatterning
tool to fabricate 1D/2D arrays of confined nanostructures (i.e., islands and wires). Small angle X-ray scattering technique
was employed to investigate the superstructure. Symmetric satellite peaks were observed, which also revealed the well-aligned
self-organized structures. In contrast, the similar superstructure was not observed during the growth of the tensile stress-induced
LaAlO3 films on SrTiO3 substrates. Based on the experimental data, the compressive stress was estimated as the main reason of the self-organized
growth. A growth model about the formation mechanisms of compressive stress-induced nanostructure was put forward and systematical
kinetics elucidations about the growth processes were also discussed to illustrate the effects of different stresses on the
growth and microstructures of the films. 相似文献
8.
H. H. Wang R. P. Wang Y. L. Zhou G. Z. Yang Z. H. Chen 《Journal of Superconductivity》2000,13(3):447-451
We have grown PrBa2Cu3O7–x
(PBCO) thin films on (100) SrTiO3 substrates using pulsed laser deposition (PLD). X-ray diffraction (XRD) studies indicate that the orientation of PBCO films varied with increasing deposition temperature: b axis oriented films can be grown at 680°C, and a axis oriented films at the temperature between 692°C and 705°C. Atomic force microscopy (AFM) reveals that a good flatness of the films was obtained with surface mean roughness of less than 24 Å, indicating that it is suitable for use as template layers in a axis oriented epitaxial YBa2Cu3O7–y
/PBCO and YBCO/tetragonal–YBCO/PBCO multilayer structures. 相似文献
9.
Polymers that form a complex with metal ions from nitrate salts can be used to prepare precursors for the production of high temperature superconductor (HTSC) ceramics that can be processed using advantageous polymer processing techniques and then pyrolyzed. This paper describes the production of HTSC from a precursor based on m-cresol formaldehyde novolak resin (mCFNR) that contains yttrium, barium and copper nitrate salts in the proportions needed for the formation of YBa2Cu3O7−x
(YBCO). The degradation of the precursor and the effects of the pyrolysis process (temperature, time, environment, substrate) were studied in detail. The mechanisms of degradation for mCFNR and for the HTSC precursors were significantly different with the precursor degradation beginning at significantly lower temperatures. The optimal pyrolysis begins in an inert atmosphere to hinder BaCO3 formation and then continues in oxygen to 950 °C. A dense orthorhombic YBCO film with preferential [001] orientation results from topotaxial growth on SrTiO3. 相似文献
10.
A. Salem A. E. Al-Salami K. A. Ziq H. Adrian 《Journal of Superconductivity and Novel Magnetism》2011,24(1-2):159-163
Bi2Sr2Ca2Cu3O10+?? HTSC epitaxial thin films with thickness in the order of 6.0?nm were prepared onto (100) aligned SrTiO3 single-crystal substrates by DC sputtering from stoichiometric targets. As-grown samples were characterized by X-ray diffraction, AC-susceptibility and scanning electron microscopy. X-ray diffraction patterns show that all obtained superconducting thin films were c-axis oriented with a Bi-2223 phase. All reflections (except the substrate ones) can be assigned to the (00l) reflections of the film material (h=k=0, l??0), indicating that the films were grown preferentially with the c-axis normal to the film plane. In order to investigate the crystal quality of these Bi-2223 films, the rocking curves of the (0012) peaks were explored by ??-scans. The rocking curve of the (0012) reflection had a full width at half maximum (FWHM) of 0.30??. This demonstrates that our prepared Bi-2223 thin films have good crystalline quality and high degree of c-axis orientation. The grain size has well known important effects in the magnetic, optical, and electrical properties of metals and alloys. High temperature superconducting thin films, obtained in this work, have nanometer grain size. The mean size of the grains of the samples were determined by X-ray diffraction (XRD) and found to be in the order of 34.8?nm. The superconducting transitions temperature of several Bi-2223 samples is about 103?K. Surface morphology of the films and chemical composition were studied using scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis (EDX). 相似文献
11.
Andrew J. Francis 《Thin solid films》2006,496(2):317-325
Pulsed laser deposition has been used to grow epitaxially oriented thin films of Cu and Pt on (100)-oriented SrTiO3 and LaAlO3 substrates. X-ray diffraction results illustrated that purely epitaxial Cu(100) films could be obtained at temperatures as low as 100 °C on SrTiO3 and 300 °C on LaAlO3. In contrast, epitaxial (100)-oriented Pt films were attained on LaAlO3(100) only when deposited at 600 °C. Atomic force microscopy images showed that films deposited at higher temperatures consisted of 3D islands and that flat, layered films were obtained at the lowest deposition temperatures. Importantly, Cu films deposited at 100 °C on SrTiO3(100) were both purely (100)-oriented and morphologically flat. Pt and Cu films displaying both epitaxial growth and smooth surfaces could be obtained on LaAlO3(100) only by using a three-step deposition process. High-resolution transmission electron microscopy demonstrated an atomically sharp Cu/SrTiO3 interface. The crystalline and morphological features of Cu and Pt films are interpreted in terms of the thermodynamic and kinetic properties of these metals. 相似文献
12.
Zhongchang Wang Rong Sun Chunlin Chen Mitsuhiro Saito Susumu Tsukimoto Yuichi Ikuhara 《Journal of Materials Science》2012,47(13):5148-5157
We demonstrate that the atomic structures, electronic states, and bonding nature of the interface between SrTiO3 substrate and anatase TiO2 thin films could be related and technologically manipulated at the atomic level. Applying advanced transmission electron
microscopy, the grown anatase TiO2 thin films are found to make a clean and direct contact to the SrTiO3 substrates in an epitaxial, coherent, and atomically abrupt way. The atomic-resolution microscopic images reveal that the
interface comprises SrO-terminated SrTiO3 and Ti-terminated TiO2 with the interfacial Ti of TiO2 sitting above the hollow site, which is confirmed theoretically to be the most energetically favorable. Quantitatively, the
first-principles calculations predict that the oxygen sublattice at the interface undergoes a notable reconstruction, i.e.,
the interfacial O atoms of TiO2 are displaced largely toward the SrO plane of the SrTiO3, flattening the originally zigzag TiO2 atomic chains. Consequently, the interfacial layers suffer a remarkable modification in the charge accumulation and also
a deviation in the density of states from their bulk counterparts, indicating that the substrate can have an impact on the
deposited thin films electronically. Using several analytic methods, the SrTiO3/TiO2 interface is found to take on a metallic nature, and the interfacial bonding is determined to be of a mixed covalent and
ionic character. This combined experimental and theoretical investigation gains insight into the complex atomic and electronic
structures of the buried interface, which are fundamental for relating the atomic-scale structures to their properties on
a quantum level. 相似文献
13.
Shao-Bo Mi 《Thin solid films》2011,519(7):2071-2074
Thin films of SrCuO2 with tetragonal structure have been epitaxially grown on SrTiO3 (001) substrates by high-oxygen pressure sputtering technique. The interface structure between SrCuO2 and SrTiO3 and configuration of defects in SrCuO2 thin films have been characterized by means of high-resolution transmission electron microscopy. Two types of film-substrate interface structure coexist and are determined as bulk-SrO-TiO2-Sr(O) -CuO2-Sr-bulk and bulk-SrO-TiO2-SrO-Sr(O) -CuO2-Sr-bulk. The planar faults with double SrO atomic layers in {100} planes in SrCuO2 thin films are observed, which mainly arise from the coalescence of these two types of film-substrate interface structure. Meanwhile, planar faults in {110} planes are observed in thin films and structural models are proposed. 相似文献
14.
Ning Zhao Lixi Wan Liqiang Cao Daquan Yu Shuhui Yu Rong Sun 《Materials Letters》2011,65(23-24):3574-3576
Polycrystalline BaTiO3/Ba0.6Sr0.4TiO3/SrTiO3 (BT/BST/ST) multilayer thin films with different periodicities have been deposited on Pt/Ti/SiO2/Si substrates by using a sol–gel method. The multilayer thin films were crack free, compact and crystallized in a perovskite structure. The dielectric constant of the multilayer thin films was significantly increased and the dielectric loss was almost the same as those of uniform BT, ST and BST thin films. The dielectric constant increased with increasing stacking periodicity as the thickness of each individual layer decreased. The multilayer thin films showed excellent dielectric properties and can be promisingly used for the dielectric layer of silicon-based embedded capacitors in package substrate. 相似文献
15.
Enhanced electrical characteristics of sol–gel-derived amorphous SrTiO<Subscript>3</Subscript> films
Manwen Yao Fei Li Yong Peng Jianwen Chen Zhen Su Xi Yao 《Journal of Materials Science: Materials in Electronics》2017,28(5):4044-4050
Amorphous SrTiO3 thin films were fabricated on Pt (100)/Ti/SiO2/Si substrates by sol–gel and spin-coating technology and their surface and cross-section morphology were characterized by using field emission scanning electron microscopy. A broad absorption band at about 3390 cm?1 owing to the stretching vibrations of hydroxyl groups in the absorbed water was observed from fourier transform infrared spectroscopy. J–E measurements were used to investigate the electrical characteristics of SrTiO3 films. The breakdown characteristics and leakage current are strongly dependent upon their electrode materials. SrTiO3 films with Al top electrodes exhibit significantly higher breakdown strength and much lower leakage current than those with Au top electrodes. Moreover, samples with Al electrodes exhibit distinct electrical characteristics when a negative voltage was applied under different testing conditions. The surface chemical state of aluminum was analyzed by using X-ray photoelectron spectroscopy, indicating that the 45 nm thick Al electrode was completely transformed into aluminum oxide layer when a positive voltage was applied. These results show that the anodic oxidation of the Al electrodes and films is suggested to be responsible for the enhanced electrical characteristics of SrTiO3 thin films. 相似文献
16.
Pulsed laser deposition is used to ablate thin superconducting YBCO films on SrTiO
3
substrates. The most important parameters of thin superconducting films are high critical current density, ability to stand magnetic fields and smoothness of surfaces. Smoothness is important in fabrication of layered structures and for research of basic properties of thin superconducting structures. The target sintered from YBCO nanopowder is a promising material for making films which meet most of the requirements above. Investigations by AFM show that our target has grains about one order of magnitude smaller than usual grain size of commercial targets. At optimal deposition parameters, the oxygen pressure of 0.4 torr in the chamber and the substrate temperature 725°C, films with T
c = 90 K, J
c =8 × 106
A/cm
2
(77 K) and RMS surface roughness = 1.5 nm are obtained. Thermal annealing of the deposited films for 18 h at 900°C further increases the value of J
c
. 相似文献
17.
Barium titanate (BaTiO3) thin films prepared on magnesia, silicon and strontium titanate substrates by r.f. sputtering has been investigated. As a function of substrate and annealing temperatures, the crystal structure and shape were examined by X-ray diffraction and scanning electron microscopy. Thin films were grown on both MgO and silicon substrates; they were amorphous when deposited on MgO if the substrate temperature was less than 450 °C, while for those grown on silicon the temperature had to be less than 500 °C. Above these elevated temperatures, the films were crystalline, with cubic symmetry. After annealing the thin films on magnesia, the crystal structure changed from cubic to tetragonal phase above 1100 °C; thebe c-axis or annealing thus caused the grain growth of the BaTiO3. The thin films on SrTiO3 were found toc-axis oriented tetragonal films for a substrate temperature above 500 °C. 相似文献
18.
Potassium tantalate niobate (KTN) KTa0.65Nb0.35O3 powders and thin films of perovskite structure were prepared through sol–gel processing. A homogeneous and stable precursor
solution was obtained from tantalum ethoxide, niobium ethoxide, and potassium ethoxide in absolute ethanol with a key additive
of acetic acid. Powder gels were obtained by exposing the solution to atmospheric water, thus hydrolysing the solution. The
precursor powder crystallized to pyrochlore at 600 °C, and then completely transformed to perovskite at 750 °C. Alternatively,
thin films were deposited on quartz glass, silicon, sapphire, yttria-stablized ZrO2, LaAlO3, SrTiO3 and platinum-coated silicon plates, using the spinning technique. The crystal structure of the KTN thin films showed a strong
dependency on the crystal structure of the substrates. Crack-free and transparent epitaxial KTN thin films were successfully
prepared on SrTiO3 (1 0 0) and (1 1 0) substrates and highly oriented KTN films on R-plane sapphire and LaAlO3 (0 1 2) substrates. The chemical composition of the KTN powders and thin films is in good agreement with the atomic ratio
of the starting materials.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
19.
M. S. Raven 《Journal of Materials Science: Materials in Electronics》1994,5(3):129-146
This paper reviews the background to glow-discharge sputter deposition of thin films and the deposition of YBCO superconducting thin films in particular. The background to sputtering is briefly reviewed with reference to the recent literature on analytical and numerical techniques for investigating radiofrequency (r.f.) plasmas, magnetron sputtering and hysteretic behaviour in reactive sputtering. Low-energy, ion-assisted deposition techniques are briefly reviewed, and the effect of ion-beam interactions on film nucleation and growth is also discussed. The background to the sputter deposition of high-temperature superconductors (HTS) is given along with the choice of sputtering system for HTS deposition. Resputtering effects, off-axis andin-situ/ex-situ processing are also discussed. The sputter deposition of YBa2Cu3O
x
is considered in detail along with theP-T-x oxidation conditions and the tetragonal/orthorhombic line. Typical experimental arrangements and results for YBCO sputtered onto SrTiO3 and MgO are given. The problem of producing high-critical-current-density polycrystalline films by sputtering is also discussed. 相似文献
20.
C. N. L. Edvardsson J. Birch U. Helmersson 《Journal of Materials Science: Materials in Electronics》1999,10(3):203-208
The strain relaxation of SrTiO3 r.f. magnetron sputter-deposited thin films on LaAlO3 substrates have been studied by x-ray diffraction mapping. An investigation of different x-ray optics shows that a, so called, hybrid mirror monochromator in combination with a triple-bounce analyser crystal provides very good conditions for characterization of thin distorted films grown epitaxially onto substrates with high structural order. The in-plane and out-of-plane lattice parameters of the SrTiO3 films could accurately be determined since the x-ray diffraction optics enabled the splitting of substrate peaks, caused by the twinning in the rhombohedral LaAlO3 to be resolved and, provided film peak intensities are high enough, to precisely establish their positions. Films in the thickness range 9.3–144.0 nm were found to be partially relaxed, having a tetragonal distortion due to in-plane strain that was found to decrease with increasing film thickness, approaching an undistorted SrTiO3 lattice parameter of 0.3927 nm. This value is 0.6% larger than the bulk indicating that the compositions of the films were slightly non-stoichiometric. The strain relaxation of the grown films was found to follow the general trend of a predicted strain–thickness relation based on energy density balance considerations regarding misfit dislocations and lattice strain. 相似文献