Papers by Keyword: Chemical Solution Deposition

Abstract: With Energy shortage becoming increasingly severe, the application of high-temperature superconducting material is considerable prospects. Economic, efficient and energy-saving preparation techniques become the key factors for the large-scale applications of REBa₂Cu₃O_7-δ superconducting coated conductors. A rapid route of chemical solution deposition (CSD) has been developed to prepare YBa₂Cu₃O_7-δ(YBCO) /SmBiO₃ (SBO)/NiO/NiW coated conductor. In this process, the precursor film decomposition time is greatly reduced and the whole time of preparing SBO film is less than 2 hours. Therefore, it greatly saves the energy and reduces the cost of preparation. The subsequent YBCO layer was successfully grown on the SBO/NiO/NiW and the T_c is about 89 K and the J_c is about 1.46 MA/cm² in self-field at 77 K. The results show that using rapid CSD preparation of YBCO/SBO/NiO/NiW is one of the effective energy-saving techniques.

Abstract: Hybrid nanostructured Metal Oxide Semiconductor (MOS) capacitor was fabricated on silicon substrates (n-type) using chemical solution deposition with YMnO3 as an oxide layer. Electrical properties of MOS capacitor have been investigated with frequency dependence capacitance-voltage (C-V) characterization. The surface morphology of deposited layer was studied using the Atomic Force Microscopy (AFM). Hysteresis in the C-V loop and change in the values of Cminimum were described by a charge trap mechanism in the multiferroic oxide layer of MOS devices. While anomalous behavior in saturation capacitance in the inversion as well as in accumulation region and a shift in threshold voltage (V_T) were explained in the vicinity of frequency depended Debye length (L_Debye).

Abstract: ZnO nanorods (NRs) arrays were synthesized by chemical solution deposition (CSD) method on commercial glass substrate with ZnO thin film act as seed layer prepared by sol-gel spin coating. The effect of annealing temperature of 150°C, 250°C and 500°C, respectively, on the structural growth was investigated. The observation reveals the structural improvement as the annealing temperature increased. The influence of gadolinium doping to ZnO NRs arrays was explored upon the structural and optical features. The FESEM imaging along with XRD, AFM and UV-Vis analysis were conducted to dissect the information gained by performing a study case on various gadolinium doping content in the range of 1 at. % to 4 at. %. Based on the results, the correlation between the doping content were drawn in details in this paper.

Abstract: Ferroelectric thin film devices have been demonstrated using Ba_xSr_1-xTiO₃ (BST) as a light intensity detector. Various compositions of BST (x=0.7, 0.8 and 0.9) were prepared using Chemical Solution Deposition method. Solution of barium acetate, strontium acetate, titanium (IV) iso-propoxide in a mixture of acetic acid and ethylene glycol was spin-coated onto a silicon substrate. The BST film was annealed at 800°C. The microstructure and the crystalline characterization of BST were studied using X-Ray Diffraction (XRD) pattern with General Structure Analysis System (GSAS) refinement. The film thickness was measured using Scanning Electron Microscopy (SEM). The response of BST film to source of light intensity was investigated with IRC meter and resonator coupling. The results show that the resistance of a thin BST film decrease as the intensity of light increase. On resonator coupling, V_OUT shows a slight increases as the intensity of light increases.

Abstract: . Perovskite manganite Pr_0.7Ca_0.3MnO₃ (PCMO) thin film nanostructures were grown on different substrates by chemical solution deposition to investigate its electrical switching properties. Planar structures consisting of Ag/Pr_0.7Ca_0.3MnO₃/Ag grown on SiO₂, Si (100), LaAlO₃ (100) and MgO (100) were characterized by grazing incidence X-ray diffraction, atomic force microscopy and electrical measurements. In each case, single PCMO phase formation and smooth surface morphology was confirmed by XRD and AFM, respectively. Four terminal current voltage characteristics of Ag/PCMO/Ag planar geometry exhibited a sharp transition from a low resistance state (LRS) to a high resistance state (HRS) with a high resistance switching ratios of the order of 950 for PCMO films grown on quartz was estimated at room temperature. High resistance switching ratios were found to depend on the substrate, suggesting a role of lattice mismatch for resistance switching. We have observed that higher mismatch lead to better resistance switching in this compound. The observed conduction characteristics provide direct evidence of substrate strain induce resistance switching in the Pr_0.7Ca_0.3MnO₃.

Abstract: sup>57Fe-enriched BiFeO₃ (BFO) thin films were fabricated on SiO₂/Si substrates from a stoichiometric precursor solution by chemical solution deposition process. The Bi/Fe molar ratio of the thin films decreased from 0.95 to 0.80 with increase in the sintering temperature. A perovskite phase and flat surface were obtained in the BFO thin films sintered at 500 and 600 °C. However, the ⁵⁷Fe Mössbauer spectra showed a mixture phase due to amorphous and/or Bi₂Fe₄O₉ phases in the BFO thin films. The valence state of Fe ions of the BFO thin films was confirmed to be only Fe³⁺ by the Mössbauer spectra.

Abstract: Lead-free ferroelectric (Bi_0.5Na_0.5)TiO₃ (BNT) thin films were prepared by chemical solution deposition. BNT and Mn-doped BNT precursor thin films crystallized in the perovskite single phase at 700 °C on Pt/TiO_x/SiO₂/Si substrates. The leakage current density of the perovskite BNT films, especially in the high applied field region, was reduced by doping with a small amount of Mn. Also, Mn doping markedly improved the ferroelectric properties of the films. 0.5 and 1.0 mol% Mn-doped BNT thin films exhibited well-shaped ferroelectric polarization (P) electric field (E) hysteresis loops at room temperature. Furthermore, the 1 mol% Mn-doped BNT films showed a typical field-induced strain loop, and the effective d₃₃ values were estimated to be about 60 pm/V.

Abstract: Thin films of (La,Sr)MnO₃ (LSMO) were fabricated by industrial-versatile chemical solution deposition (CSD) technique. Well [100]-oriented LSMO films were fabricated at 650-750 °C by use of buffer layers of LaNiO₃ buffer layer on a silicon substrate. The product of lower electrical resistivity is promising as an electrode of fatigue-free ferroelectric capacitor.

Abstract: Bi-based perovskite-type oxide materials such as BiFeO₃ (BFO) and Bi (Zn_1/2Ti_1/2)O₃ and the related compounds receive much attention and have been developed actively as important candidates for Pb-free ferroelectric materials instead of toxic Pb-based perovskite oxide materials. Recently, many researches have been reported for thin films of Bi-based materials by various film-deposition techniques for actual application of semiconductive devices, microactuators, etc. In this study, we tried preferential crystal growth of BFZT films on semiconductive silicon substrates using uniaxial-(100)-oriented LaNiO₃ (LNO) buffer layer. BFO films were fabricated via chemical solution deposition (CSD) technique on platinized silicon wafer [(111)Pt/TiO₂/(100)S and (100)LNO-coated platinized silicon [(100)LNO/(111)Pt/TiO₂/(100)S substrates. XRD analysis indicated that the films fabricated on (111)Pt/TiO₂/(100)Si substrate consisted of randomly-oriented BFZT crystal with lower crystallinity. On the other hand, the films on (100)LNO/(111)Pt/TiO₂/(100)Si consisted of uniaxial-one-oriented BFZT crystal with higher crystallinity. The crystallization temperature these films were 500°C, respectively. These results suggest that the BFZT crystal was grown successfully on uniaxial oriented (100)LNO plane which also had perovskite-type crystal structure. Consequently, one-oriented BFZT films were prepared on Si substrate successfully using (100)LNO buffer layer.

Abstract: Ferroelectric 0.7BiFeO₃-0.3BaTiO₃ and 0.7BiFe_0.95Mn_0.05O₃-0.3BaTiO₃ thin films were prepared by the chemical solution deposition. Perovskite single-phase thin films with homogeneous surface morphology were successfully fabricated at 700°C on Pt/TiO_x/SiO₂/Si substrates. Although typical polarization (P)-electric field (E) hysteresis loops were observed for 0.7BiFeO₃-0.3BaTiO₃ thin films, their insulation resistance was relatively low at room temperature. Mn doping for Fe site of the 0.7BiFeO₃-0.3BaTiO₃ was very effective in improving leakage current properties. In 0.7BiFe_0.95Mn_0.05O₃-0.3BaTiO₃ thin films, the abrupt increase in leakage current was suppressed even at high electric fields, leading to the well-shaped P-E hysteresis loops at ambient temperatures. Remanent polarization and coercive field of the 0.7Bi (Fe_0.95Mn_0.05)O₃-0.3Bi_0.5Na_0.5TiO₃ films at room temperature were approximately 26 μC/cm² and 130 kV/cm, respectively.