Crystallization of Epitaxial Lanthanum Aluminate and Spinel Thin Films Derived from Nitrate Precursors

1994 ◽  
Vol 341 ◽  
Author(s):  
Man Fai Ng ◽  
Michael J. Cima
Keyword(s):  
Thin Films ◽  
Epitaxial Film ◽  
Amorphous Film ◽  
Zero Field ◽  
Epitaxial Thin Films ◽  
Lanthanum Aluminate ◽  
Initial Nucleation ◽  
Metalorganic Deposition ◽  
Current Densities ◽  
Higher Temperature

AbstractBoth lanthanum aluminate (LaAIO 3) and spinel (MgAl2O 4) epitaxial thin films have been deposited on either planar and stepped (100) SrTiO3 single crystal substrates by pyrolysis of mixed nitrate precursors. The precursors pyrolyze initially into amorphous films. Nucleation of lanthanum aluminate and spinel occurs at the filnVsubstrate interface at higher temperature. Crystallization of LaAlO3 on SrTiO3 substrates occurs at approximately 650°C, whereas nucleation occurs at approximately 800'C without lattice-matched substrates. Similarly, latticematched substrates reduce the crystallization temperature of spinel to below 700°C. The epitaxial film grows at the expense of the amorphous film after the initial nucleation at the interface. The rapid growth and volume change due to the crystallization leave behind an epitaxial film with nanoporosity of 15 to 30 nm. Nevertheless, the surfaces of these films have roughness of only 6–9 Å. Ba2Ycu3O7-x films derived from metalorganic deposition of metal trifluoroacetate precursors was deposited on these epitaxial LaAlO3 films on both planar and stepped SrTiO3 substrates. The resultant YBCO films on LaAlO3 film on planar SrTiO3 substrate have critical current densities of > 2 × 106 A/cm2 at 77K and zero field.

Epitaxial Chemically Derived Lanthanum Aluminate Films for Ba2YCu3O7−x Devices

1993 ◽  
Vol 317 ◽  
Author(s):  
Man Faing ◽  
Michael J. Cima
Keyword(s):  
Substrate Material ◽  
Zero Field ◽  
Ybco Films ◽  
Lanthanum Aluminate ◽  
Transmission Electron ◽  
Nitrate Precursor ◽  
Metalorganic Deposition ◽  
Current Densities ◽  
Higher Temperature ◽  
Lattice Matched

ABSTRACTLanthanum aluminate (LaAlO3) has been used as a substrate material for depositing Ba2YCu3O7−x (YBCO) films. In the present study, chemically derived epitaxial LaAlO3 thin films were used for depositing epitaxial YBCO films. These epitaxial LaAlO3 films were deposited on both (100) SrTiO3 and (100) LaAlO3 single crystal substrates by pyrolysis of a mixed nitrate precursor. Crystallization of LaAlO3 on lattice-Matched substrates occurs at below 650°C, whereas crystallization on non lattice-Matched substrates occurs at much higher temperature. The average surface roughness of these LaAlO3 films can be as low as 7Å. The YBCO films derived from metalorganic deposition of metal trifluoroacetate precursors were deposited on these epitaxial LaAlO3 films on SrTiO3 substrates. The resultant YBCO films have critical current densities of > 2 × 106 A/cm2 at 77K and zero field. Transmission electron microscopy of these films shows that they are highly epitaxial yet have pore of about 15–30 nm in size. Chemically derived LaAlO3 films also were used to planarize stepped substrates.

Issues Concerning the Chemical Synthesis of Ceramic Superconducting Coatings in the Bi-Sr-Ca-Cu-O System with High Critical Current Densities.

1991 ◽  
Vol 249 ◽  
Author(s):  
S. J. Golden ◽  
K. J. Vaidya ◽  
T. E. Bloomer ◽  
F. F. Lange ◽  
D. R. Clarke
Keyword(s):  
Thin Films ◽  
Critical Current ◽  
Zero Field ◽  
Superconducting Thin Films ◽  
Ethyl Hexanoate ◽  
X Ray ◽  
Pole Figures ◽  
Oriented Films ◽  
Metalorganic Deposition ◽  
Current Densities

ABSTRACTSuperconducting thin films of the two Cu-layer phase in the Pb-doped Bi- Sr-Ca-Cu-O system have been fabricated on {100} LaAlO3 single crystals by the metalorganic deposition (MOD) from ethyl hexanoate precursors. Some of the major issues pertinent to the synthesis of high quality films have been studied.Thin films of composition Bi1.8Pb0.3Sr1.6CaCu2Ox given heat treatments in air at 850–860 °C for several hours had sharp resistive transitions with a Tc of 85–89 K. The zero-field transport critical current densities were in the range of 1–4×105 A.cm−2 at 77 K and 106 A.cm−2 at 45 K in 200–300 nm thick films. In contrast to caxis oriented films grown on (100) MgO, X-ray pole figures show that the polycrystalline films grown on (100) LaAlO3 are epitaxial, a result confirmed by electron channeling patterns.

Characterization of Epitaxial Superconducting YBacuO Thin Films with Three Different Orientations

1989 ◽  
Vol 169 ◽  
Author(s):  
X.K. Wang ◽  
D.X. Li ◽  
S.N. Song ◽  
J.Q. Zheng ◽  
R.P.H. Chang ◽  
...  
Keyword(s):  
Thin Films ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Orientation Dependence ◽  
Zero Field ◽  
Epitaxial Thin Films ◽  
Oriented Film ◽  
Zero Resistance ◽  
Xrd Patterns

AbstractEpitaxial thin films of YBaCuO were prepared by multilayer deposition from Y, Cu, and BaF2 sources with: (1) the a‐axis perpendicular to (100)SrTiO3; (2) the c‐axis perpendicular to (100)SrTiO3; and (3) the [110] axis perpendicular to (110)SrTiO3. XRD patterns as well as SEM and HREM images confirm that the films are highly oriented, essentially epitaxial. Both the a‐axis oriented and the c‐axis oriented films exhibit zero resistance at 91K. The [110] oriented film shows the sharpest transiton with a transition width of IK and zero resistance at 85K. The zero field critical current density, Jc, determined magnetically, is in excess of 107A/cm2 at 4.4K and 1.04 x 106A/cm2 at 77K for the c‐axis oriented film; for the a‐axis oriented film we obtained 6.7 x 106A/cm2 at 4.4K and 1.2 x 105A/cm2 at 77K. The orientation dependence of the critical current density in the basal plane of the a‐axis oriented film was studied. The largest Jc's occur along the in‐plane <100> axes of the substrate.

Strain Relaxation in Si1-xGex Thin Films on Si (100) Substrates: Modeling and Comparisons with Experiments

2005 ◽  
Vol 875 ◽  
Author(s):  
Kedarnath Kolluri ◽  
Luis A. Zepeda-Ruiz ◽  
Cheruvu S. Murthy ◽  
Dimitrios Maroudas
Keyword(s):  
Thin Films ◽  
Mechanical Response ◽  
Epitaxial Film ◽  
Film Growth ◽  
Strain Relaxation ◽  
Mean Field ◽  
Substrate Thickness ◽  
Threading Dislocation ◽  
Epitaxial Thin Films ◽  
Dislocation Generation

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.

Target stoichiometry and growth temperature impact on properties of BiVO4 (010) epitaxial thin films

CrystEngComm ◽  
2018 ◽  
Vol 20 (43) ◽  
pp. 6950-6956 ◽  
Author(s):  
Guoqiang Li ◽  
Shiwen Kou ◽  
Feng Zhang ◽  
Weifeng Zhang ◽  
Haizhong Guo
Keyword(s):  
Thin Films ◽  
Photocatalytic Activity ◽  
Growth Temperature ◽  
Epitaxial Film ◽  
Polycrystalline Sample ◽  
Epitaxial Thin Films ◽  
Phase Pure ◽  
Temperature Impact

Phase-pure BiVO4 epitaxial film fabricated from a nonstoichiometric target at 680 °C shows higher photocatalytic activity than the polycrystalline sample.

scholarly journals Dielectric anomaly and magnetic response of epitaxial orthorhombic YMnO3 thin films

2007 ◽  
Vol 22 (8) ◽  
pp. 2096-2101 ◽  
Author(s):  
X. Martí ◽  
V. Skumryev ◽  
V. Laukhin ◽  
F. Sánchez ◽  
M.V. García-Cuenca ◽  
...  
Keyword(s):  
Thin Films ◽  
Orthorhombic Phase ◽  
Growth Conditions ◽  
Magnetic Response ◽  
Zero Field ◽  
Epitaxial Thin Films ◽  
Substrate Selection ◽  
Plane Compression ◽  
Zero Field Cooling ◽  
Field Cooling

The structure, magnetic response, and dielectric response of the grown epitaxial thin films of the orthorhombic phase of YMnO3 oxide on Nb:SrTiO3 (001) substrates have been measured. We have found that a substrate-induced strain produces an in-plane compression of the YMnO3 unit cell. The magnetization versus temperature curves display a significant zero-field cooling (ZFC)-field cooling hysteresis below the Néel temperature (TN ≈ 45 K). The dielectric constant increases gradually (up to 26%) below the TN and mimics the ZFC magnetization curve. We argue that these effects could be a manifestation of magnetoelectric coupling in YMnO3 thin films and that the magnetic structure of YMnO3 can be controlled by substrate selection and/or growth conditions.

Heteroepitaxy of rare-earth hexa-aluminates on sapphire

1994 ◽  
Vol 9 (2) ◽  
pp. 410-419 ◽  
Author(s):  
K.J. Vaidya ◽  
C.Y. Yang ◽  
M. DeGraef ◽  
F.F. Lange
Keyword(s):  
Thin Films ◽  
Rare Earth ◽  
Orientation Relationship ◽  
Sapphire Substrate ◽  
Basal Plane ◽  
Intermediate Phase ◽  
Epitaxial Thin Films ◽  
Liquid Precursors ◽  
Oxygen Sublattices ◽  
Higher Temperature

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.

Ba2YCu3O7−x Thin Films with Jc>105 A/cm2 at 77 K Prepared by Metalorganic Deposition at Reduced Oxygen Pressure

1991 ◽  
Vol 249 ◽  
Author(s):  
Robert B. Hallock ◽  
W.E. Rhine ◽  
M.S. Jolly ◽  
MIchael J. Cima
Keyword(s):  
Thin Films ◽  
Spin Coating ◽  
Total Pressure ◽  
Applied Field ◽  
Methanol Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metalorganic Deposition ◽  
Zero Resistance ◽  
Current Densities

ABSTRACTSuperconducting Ba2YCu3O7-x films 0.1-0.2 gim thick were prepared by spin coating a methanol solution of Ba, Y and Cu acrylates on (100)LaAlO3 and firing to 800°C in a total pressure of 1 mm O2. X-ray diffraction showed that these films were epitaxial with the c-axis normal to the substrate. Zero resistance was achieved above 90 K and transport DC critical current densities as high as 125,000 A/cm2 were measured at 77 K in zero applied field.

Giant Electroresistance Induced by Electric Currents in Epitaxial Thin Films of Pr0.7Sr0.3MnO3

2013 ◽  
Vol 483 ◽  
pp. 130-133
Author(s):  
He Yan Liu ◽  
Liang Zhou ◽  
Ying Li ◽  
Guo Dong Liu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electric Current ◽  
Current Density ◽  
Epitaxial Thin Films ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Current Densities ◽  
A Current ◽  
Peak Resistance

Electric-current induced electroresistance effect has been investigated in epitaxial Pr0.7Sr0.3MnO3thin film grown on the (100) SrTiO3substrate. A significant change ~38% in the ratio of the peak resistance at different currents with a current density up to ~3.3×103A/cm2was achieved. Such an ER effect is more remarkable in comparing with that reported in other manganite oxides with similar current densities. Compared with that of the as-grown films, the electroresistance of the post-annealed films is smaller, while the ER effect (~14%) is obtained. Although the nature behind such an electroresistance effect has not been well understood, the field tunability of the metal/insulator transition and the electroresistance effect induced by currents might be of potential for various applications such as filed effect devices.

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