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Electrode Dependence of Local Electrical Properties of Chemical-Solution-Deposition-Derived BiFeO <sub/>3</sub> Thin Films
摘要： The nanoscale electrical properties of chemical solution deposition(CSD)-derived BiFeO3 grown on pulsed laser ablated La0.67Sr0.33MnO3//SrTiO3 (001) thin film heterostructures are investigated using a host of scanning probe microscopy techniques, including electrostatic force microscopy(EFM), scanning Kelvin probe microscopy(SKPM), piezoresponse force microscopy (PFM), and conductive AFM(CAFM). EFM and SKPM confirm the p-type nature of the CSD derived BFO thin films as well as charge accumulation at the film surface after electrical bias. For BiFeO3 films of a fixed thickness (~35 nm), the local current-voltage (I-V) behavior obtained by CAFM is strongly dependent on the La0.67Sr0.33MnO3 bottom electrode thickness. BiFeO3 films on a 20 nm thick La0.67Sr0.33MnO3 demonstrate the typical switchable diode behavior governed by polarization orientation. However, when the thickness of La0.67Sr0.33MnO3 is reduced to less than 5 nm, the BiFeO3 films show only forward diode behaviors regardless of polarization orientation, when the applied bias is up to ±4 V. Higher sweep bias (i.e. ±8V) breaks down the diode, following which the BiFeO3 film shows strong resistive switching. The interface band structure for the ultra-thin LSMO case, which is very sensitive to accumulation/depletion of carriers at the BFO-LSMO interface, is suggested as the trigger for this resistive switching.
关键词： chemical solution deposition,ferroelectric,electrical properties,ultrathin lanthanum strontium manganite,p-type bismuth ferrite thin films
更新于2025-09-23 15:23:52
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Thickness dependence of structural, morphological and optical properties of Mn-Co-Ni-O thin films grown by chemical solution deposition on SiO2/Si(100) substrate
摘要： Mn1.56Co0.96Ni0.48O4 (MCNO) thin film with different thicknesses ranging from 180 nm to 600 nm were deposited onto a SiO2/Si(100) substrate at 600 °C by using the chemical solution deposition method. The thickness dependent structural and optical properties of the MCNO films were investigated in this study. As identified by the SEM pictures and X-ray diffraction (XRD) spectra, all samples showed polycrystalline cubic spinel structure, and the stoichiometric status is improved with growing thickness according to XRD results. Spectroscopic ellipsometry spectra were measured in this study to investigate the thickness dependent optical properties of MCNO film in the range of 300-1000 nm. The samples showed three absorption structures locating at 1.6-1.9 eV, 2.6 eV, and above 3.5 eV, corresponding to the charge transfer transition involving 2p orbitals of O2- and 3d orbitals of Mn and Co ions, respectively. The absorption structure at above 3.5 eV decreases gradually as the thickness grows, while the peak around 1.6-1.9 eV weakens slightly before it enhances again with film thickness above 430 nm, which can be explained by a combined effect of crystallinity improvement and increase in Mn4+/Mn3+ ratio.
关键词： optical properties,Mn1.56Co0.96Ni0.48O4 thin film,thickness dependence,chemical solution deposition,absorption structures
更新于2025-09-23 15:22:29
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Piezoelectric properties of a near strain-free lead zirconate titanate thin films deposited on a Si substrate
摘要： Chemical solution deposition (CSD)-derived near strain-free lead zirconate titanate (PZT) thin films on a Si substrate were prepared by designing a buffer layer structure. Strain-free PZT thin films with different compositions ranging from Zr/Ti = 50/50 to 58/42 were obtained to demonstrate lattice strain effects on piezoelectric properties. Results show that a near strain-free condition was attained with a SrRuO3 (SRO: 160 nm)/(La0.5,Sr0.5)CoO3 (LSCO: 90 nm)/LaNiO3 (LNO: 120 nm)/stacking structure, even on a Si substrate. The highest effective d33 value of the near strain-free PZT thin film was observed at 53/47 composition, which is the same as bulk materials, although the highest effective d33 value was obtained from 58/42 composition under the compressive lattice strain condition.
关键词： Chemical solution deposition,Piezoelectricity,Thin films,Multilayer structure,Lattice strain,Sol-gel preparation
更新于2025-09-23 15:22:29
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Application of barium strontium titanate (BST) as a light sensor on led lights
摘要： Barium Strontium Titanate (BST) film has been successfully produced as a light sensor. The BST film was made by CSD method by reacting barium acetate, strontium acetate and titanium isopropoxide with mole fractions of 0.5; 0.5 and 1, respectively.The BST absorbance test showed that BST film is sensitive to visible light ranging from 475 to 750 nm. The film test showed maximum absorbance at three peak wavelengths, 475 nm, 593 nm, and 702 nm. The energy gap of the BST film was 1.9 eV which showed that the film produced was a semiconductor. The IV test showed that BST film is a photodiode. This was indicated by the shift of the curve when tested in light and dark conditions. The sensitivity test showed BST film is most sensitive to blue light, signified by the most significant change in resistance. The decrease in resistance of blue LED was 0.401KX/lux, while the resistance decrease of green light was 0.051KX/lux and red was 0.288KX/lux. By using optical and electrical properties, BST thin film could be used as light sensors to detect LED lights.
关键词： semiconductor,I-V,absorbance,chemical solution deposition,Barium strontium titanate
更新于2025-09-19 17:13:59
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The composition and poling-dependent photovoltaic studies in ferroelectric (Bi1?xSrx)(Fe1?xTix)O3 thin films
摘要： The polycrystalline (Bi1?xSrx)(Fe1?xTix)O3 (x = 0.0, 0.05, 0.10, and 0.20) thin films were grown on Pt(111)/TiO2/SiO2/ Si(100) substrates using chemical solution deposition technique. X-ray diffraction pattern revealed that pure BiFeO3 film is crystallized in rhombohedrally distorted crystal structure. However, the patterns for doped samples displayed a mixed-phase (rhombohedral + tetragonal) structure. The Raman studies revealed the emergence of B mode related to the tetragonal phase along with the modes corresponding to the rhombohedral phase in doped systems. The photovoltaic studies displayed a large photovoltaic response for the parent compound with an open-circuit voltage of 0.47 V. However, it showed a decrease in the photovoltaic response with an increase in composition x. The composition-dependent photovoltaic response could be correlated to the evolution of tetragonal phase fractions and the polarization. Additionally, the poling-dependent photovoltaic studies revealed the dominant role played by the polarization in comparison with the interface Schottky effect. This work gives an improved understanding of the ferroelectric photovoltaic mechanism and, therefore, may offer guidelines to design and optimize photovoltaic materials.
关键词： ferroelectric,photovoltaic,chemical solution deposition,polarization,thin films
更新于2025-09-12 10:27:22
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Zirconium distribution in solution-derived BaZrO3 - YBa2Cu3O7-δ epitaxial thin films studied by X-ray photoelectron spectroscopy
摘要： Superconducting YBa2Cu3O7-δ films with different amounts of BaZrO3 nanoinclusions were deposited on SrTiO3(001) by low-fluorine chemical solution deposition with the aim of introducing artificial vortex pinning centres. The Zr concentration over the film thickness could be determined by X-ray photoelectron spectroscopy combined with Ar+ ion etching. The Zr/Y ratio has a constant behaviour in the film's bulk. Zr segregation occurs near the surface and Zr diffusion into the substrate is observed near the interface. Conversely, Sr and Ti from the substrate diffuse into the films. Y3d lineshape analysis and X-Ray Diffraction data pointed out that Ti diffusion causes the formation of Y-Ti-O based spurious phases.
关键词： Chemical solution deposition,X-ray photoelectron spectroscopy,Vortex pinning,Yttrium barium copper oxide,Barium zirconate
更新于2025-09-10 09:29:36
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Influence of Ba <sup>2+</sup> Consumption and Intermediate Dwelling during Processing of YBa <sub/>2</sub> Cu <sub/>3</sub> O <sub/>7</sub> Nanocomposite Films
摘要： Achieving high critical current densities (Jc) with small artificial pinning centers is a crucial challenge for YBa2Cu3O7-δ (YBCO) nanocomposite thin films fabricated using chemical solution deposition methods. In this work, the YBCO texture, structure purity and its Jc properties were improved by understanding the influence of preformed ZrO2 nanocrystals (Ba2+ consumption) during the nucleation and growth mechanism. This comprehensive study leads to an additional intermediate dwelling step during thermal process to increase the YBCO nuclei density before the YBCO growth, resulting to a self-field Jc of 5-6 MA cm-2 at 77 K for undoped and ZrO2-doped YBCO films. Counter-intuitively, the space and size distribution of the ZrO2 nanocrystals in the YBCO matrix are independent of this intermediate dwelling step.
关键词： vortex pinning,nanocomposite,nanoparticles,low-fluorine YBCO,chemical solution deposition
更新于2025-09-09 09:28:46