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The atomically finished rutile TiO2 (1 0 1) substrate was obtained by an appropriate surface cleaning and subsequent annealing of commercially available single crystals. The morphology, composition and crystallinity of the ultrasmooth surface were confirmed by an atomic force microscope (AFM), an X-ray photoelectron spectroscopy (XPS) and a reflection-high-energy-electron diffraction (RHEED), respectively. The optimum process for obtaining the ultrasmooth surface was found to be the annealing at the temperature of 700 °C for 1 h in air after the ultrasonic cleaning immersing in organic solvents and subsequent 20% HF water solution. Furthermore, the homo-epitaxial growth on the ultrasmooth substrate was performed and compared with the hetero-epitaxial growth of TiO2 film on a stepped α-Al2O3 (1 0 &1macr; 2) substrate. [Copyright &y& Elsevier]

By using a combinatorial laser molecular beam epitaxy (MBE)/in situ low energy electron diffraction (LEED) and scanning tunneling microscope (STM) system, we have investigated a behavior of transition metals (TMs) deposited on the anatase TiO2 (0 0 1)–(4 × 1) surface systematically. TiO2 (0 0 1) thin films were fabricated on 0.05 mol% Nb doped SrTiO3 (0 0 1) substrates and on each of those films TMs were deposited with gradual variation of its deposition amount. In situ analysis of the libraries with LEED and STM revealed the surface morphologies that were sensitive to TM element and on the process temperature. The results are discussed in terms of the oxide formation enthalpy ΔH kJ mol−1 of TMs. [Copyright &y& Elsevier]

Abstract: Epitaxial Sr(V x Cr y Ti1−x−y )O3 () ternary composition spreads were grown on two different single crystal substrates, LaAlO3 and Nb-doped SrTiO3, by use of combinatorial laser molecular beam epitaxy with a specially patterned slide masking plate. The photocatalytic activity on the composition spreads was evaluated by the photo-reduction of Ag+ in an AgNO3 aqueous solution to deposit Ag metal on the spreads. The V-doping effect was found to depend greatly on the substrate: the photodeposition of Ag was much enhanced in the composition region of SrV0.05Ti0.95O3 only on the Nb-doped SrTiO3, but not on the LaAlO3 and non-doped SrTiO3. [Copyright &y& Elsevier]

K2NiF4-type Sr2Rh1−xRuxO4 (0≤x≤1) composition-spread films were fabricated on (LaAlO3)0.3–(Sr2AlTaO6)0.7 (LSAT) substrate by using the combinatorial PLD method. From a temperature spread combinatorial deposition, Sr2RhO4 (x=0) is found to grow epitaxially only in a narrow temperature range, i.e. 735±15 °C. By varying the composition and temperature along x and y axes of the substrate, respectively, two-dimensional (2D) libraries of Sr2Rh1−xRuxO4 (0≤x≤1) films were fabricated to map the growth temperature dependence of film crystallinity for the full range of x=0–1. The optimum epitaxial growth temperature exhibited clear dependence on the compositional variation, x. From measurements of the electric conductivity of the films, metal–insulator–metal transitions were detected as the compositional parameter x increased from 0 to 1. [Copyright &y& Elsevier]

Abstract: Bi x Y3−x Fe5O12 thin films have been grown on GGG (Gd3Ga5O12) (111) substrates by the combinatorial composition-spread techniques under substrate temperature (T sub) ranging from 410 to 700°C and O2 pressure of 200mTorr. In order to study the effect of substrates on the deposition of Bi x Y3−x Fe5O12 thin films, garnet substrates annealed at 1300°C for 3h were also used. Magneto-optical properties were characterized by our home-designed magneto-optical imaging system. From the maps of Faraday rotation angle θ F, it was evident that the Faraday effect appears only when T sub =430–630°C. θ F reaches to the maximum value (∼6°/μm, λ =632nm) at 500°C, and is proportional to the Bi contents. XRD and EPMA analyses showed that Bi ions are easier to substitute for Y sites and better crystallinity is obtained for annealed substrates than for commercial ones. [Copyright &y& Elsevier]

Abstract: The combinatorial approach to materials synthesis was employed for the quick screening of a flux material for liquid phase-mediated epitaxy of Bi4Ti3O12 single crystal film. A series of ternary flux libraries composed of two self-fluxes (Bi2O3 and Bi4Ti3O12) and an impurity flux (VO x , WO x , CuO x , BiPO x , BaO, MoO x ) were fabricated on the SrTiO3 (001) substrates. Then, stoichiometric Bi4Ti3O12 was grown on each one of these flux libraries at a temperature presumed to melt the flux. High-throughput characterization with the concurrent X-ray diffraction (XRD) method resulted in the discovery of a novel flux material, CuO, containing Bi2O3, for Bi4Ti3O12 single crystal film. [Copyright &y& Elsevier]

A series of RECa4O(BO3)3 (RECOB) thin films (RE=Rare earth elements) was fabricated on ultrasmooth GdCOB (0 1 0) substrates by laser molecular beam epitaxy (MBE) method to explore the optimal growth conditions and to evaluate the luminescent properties. The growing surface of the film on a temperature gradient substrate was diagnosed with scanning reflection high energy electron diffraction (S-RHEED) system for quickly specifying optimum growth temperature and its dependence of rare earth element. The lowest temperature for epitaxial film growth was defined by the appearance of streak pattern in RHEED and it reflected the lattice matching with the substrate. TbCOB and EuCOB emitted respectively very bright green (543 nm) and red (611 nm) light, indicating that they are promising new phosphors. It is noteworthy that we could detect a remarkably strong red emitting region in the EuCOB–ScCOB–PrCOB ternary composition spread library. [Copyright &y& Elsevier]

We have found unusual re-evaporation effect on the surface morphology of GdxY1−xCa4O(BO3)3 (GdxY1−xCOB) films grown by combinatorial laser molecular-beam epitaxy. The surface morphologies of the GdxY1−xCOB films grown on the atomically flat (0 1 0) GdCa4O(BO3)3 (GdCOB) substrates were strongly dependent on the deposition conditions such as substrate temperature and laser repetition rate. Decreasing the substrate temperature and/or increasing the laser repetition rate improved the surface morphology of the film since at such deposition conditions, re-evaporation which may make film surface rough could be effectively restrained. GdxY1−xCOB film grown at 500 °C and 4 Hz exhibited the ultra-smooth surface like that of the atomically smooth (0 1 0) GdCOB substrate. Under such conditions, intensity monitoring of reflection high-energy electron diffraction revealed the layer-by-layer growth of the film. Using this regulated growth behavior of the films we have successfully fabricated such nano-structured films as [GdCOB/YCa4O(BO3)3] superlattices. [Copyright &y& Elsevier]

A series of MHfO3:Tm3+ (M=Ca, Sr and Ba) films were fabricated on SrTiO3 (0 0 1) substrate by using combinatorial pulsed laser deposition (PLD) technique. Their crystal structures and luminescence properties were characterized by the concurrent X-ray diffraction (CXRD) and by the cathodoluminescence (CL) using 5 kV electron beam, respectively. By monitoring the reflection high energy electron diffraction (RHEED) intensity oscillation, the growth of MHfO3:Tm3+ films were optimized to proceed in a epitaxial layer-by-layer fashion. Different from bulk powders, which had the highest CL intensity in SrHfO3:Tm3+, the composition spread film of Sr1−xCaxHfO3:Tm3+ (x=0–1) exhibited the highest CL intensity at x=0.7 rather than SrHfO3:Tm3+ (x=0). This anomalous behavior in the films is discussed in view of the stress effect from the substrate. [Copyright &y& Elsevier]