Chemical Solution Deposition Technique Research Articles

Tunable multiferroic properties of Mn substituted BiFeO3 thin films

The current study explored the influence of Mn substitution on the electrical and magnetic properties of BiFeO3 (BFO) thin films synthesized using low cost chemical solution deposition technique. X-ray diffraction analysis revealed that pure rhombohedral phase of BiFeO3 was transformed to the tetragonal structure with P4mm symmetry on Mn substitution. A leakage current density of 5.7×10−4A/cm2 which is about two orders of magnitude lower than pure BFO was observed in 3% Mn doped BFO thin film at an external electric field >400kV/cm. A well saturated (p-E) loops with saturation polarization (Psat) and remanent polarization (2Pr) as high as 60.34 µC/cm2 and 25.06 µC/cm2 were observed in 10% Mn substituted BFO thin films. An escalation in dielectric tunability (nr), figure of merit (K) and quality factor (Q) were observed in suitable Mn doped BFO thin films. The magnetic measurement revealed that Mn substituted BFO thin films showed a large saturation magnetization compared to pure BFO thin film. The highest saturation ~31emu/cc was observed for 3% Mn substituted BFO thin films.

Improved Performance of YIG (Y3Fe5O12) Films Grown on Pt‐Buffered Si Substrates by Chemical Solution Deposition Technique

High‐quality Yttrium iron garnet (YIG) films with crack‐free surface and improved magnetic performance were grown on platinum (Pt)‐buffered Si substrates by chemical solution deposition technique. The saturation magnetization of obtained YIG films can reach 124 emu/cm3, which was the 88% theoretical value of YIG single crystal. The effects of annealing condition were also discussed. When annealed at 750°C for 1 h, YIG films showed a very small coercive field of 12 Oe and the peak‐to‐peak ferromagnetic resonance linewidth can be as low as 95 Oe at 9.10 GHz. The results demonstrated that YIG films prepared on Pt‐buffered Si substrates can be beneficial to the application of YIG films to integrated devices.

BiFeO3/BaTiO3 Multilayer Structures for Solar Energy Harvesting Application

Abstract The BiFeO3/BaTiO3 (BFO/BTO) multilayer structures with varying number of individual layers from two to seven were prepared using chemical solution deposition (CSD) technique towards the ferroelectric photovoltaic applications. The BFO/BTO multilayer structure with six stacking layers exhibited maximum value of Voc=1.80 V and JON/OFF=2.955×103 due to enhanced ferroelectric properties which is attributed to significant interface coupling between 6 stacking layers of BFO and BTO. Good retention and high stability of transient current response were observed over multiple cycles of light illumination (on and off) highlighting the potential of fabricated photovoltaic cell based on multilayer structure having six stacking layers of BiFeO3 and BaTiO3 towards the solar energy harvesting applications.

Development of Biaxially Textured LZO Film on Cold-Rolled Metal Substrate

La2Zr2O7 (LZO) film grown by the chemical solution deposition (CSD) technique is a widely studied buffer layer for YBa2Cu3O7-x film growth on a rolling-assisted biaxially textured (RABiT) substrate. A biaxially textured LZO film is epitaxially grown on a cube-textured metal substrate. In a RABiT substrate, cube texture is obtained as primary recrystallization of heavily cold-rolled fcc metals and is normally developed before CSD film deposition to obtain an oriented film growth. In this paper, we show that a biaxially textured LZO film can be grown by depositing the precursor solution directly on a cold-rolled fcc metal substrate and performing a single heat treatment. In fact, we show that if the recrystallization temperature of the metallic substrate is lower than the nucleation temperature of the film, a biaxially textured film is obtained as a result of transient cube texture transfer. Biaxially textured LZO films grown on cold-rolled substrates are compared with films grown on recrystallized substrates. In particular, the growth of LZO on either pure-Cu- or Ni-based substrate was studied. Compared with the LZO film grown on a cube-textured substrate, LZO grown on a cold-rolled substrate shows similar structural properties and morphology. Moreover, films are well adherent without cracks or delamination, suggesting that grain boundary migration in the metallic substrate has no detrimental influence on the film. In some cases, secondary recrystallization of the substrate occurs, without affecting the quality of the LZO film.

Giant Magnetoelectric Effect in PZT Thin Film Deposited on Nickel

Abstract The magnetoelectric (ME) effect has been investigated in lead zirconate titanate (PZT) thin film deposited on nickel foil using chemical solution deposition (CSD) technique. The synthesized PZT thin films are found to possess perovskite structure without presence of any intermediate layer. PZT thin film deposited on nickel foil exhibits a good ferroelectric property with a high remnant polarization of about 86 µC/cm2.The ferroelectric loop has been modeled using domain wall theory to verify the behavior of the ferroelectric domains. It is observed that deposition conditions, specially annealing temperature, play a crucial role in enhancing the magnetoelectric effect. A high ME coefficient of 220 mVcm–1Oe–1 at a bias magnetic field of 50 Oe has been obtained due to enhanced magnetoelectric coupling between PZT film and nickel foil.

Photovoltaic effect in BiFeO3/BaTiO3 multilayer structure fabricated by chemical solution deposition technique

Photovoltaic (PV) properties of bismuth ferrite (BFO) and barium titanate (BTO) multilayered ferroelectric BFO/BTO/BFO/BTO thin film structure deposited on Pt/Ti/SiO2/Si substrates using chemical solution deposition technique are presented. X-ray diffraction analysis confirms pure phase polycrystalline nature of deposited perovskite multilayered structures. Simultaneously both distorted rhombohedral (R3c) and tetragonal phases (P4mm) of the respective BFO and BTO components are also well retained. The ferroelectric sandwiched structures grown on fused quartz substrates exhibit high optical transmittance (~70%) with an energy band gap 2.62eV. Current–voltage characteristics and PV response of multilayered structures is determined in metal-ferroelectric-metal (MFM) capacitor configuration. Considerably low magnitude of dark current density 1.53×10−7A at applied bias of 5V establish the resistive nature of semi-transparent multilayered structure. Enhanced PV response with 40nm thin semitransparent Au as top electrode is observed under solid-state violet laser illumination (λ – 405nm, 160mW/cm2). The short circuit current density and open circuit voltage are measured to be 12.65µA/cm2 and 1.43V respectively with a high retentivity. The results obtained are highly encouraging for employing artificial multilayered engineering to improve PV characteristics.

Growth and characterization of yttrium iron garnet films on Si substrates by Chemical Solution Deposition (CSD) technique

Yttrium Iron Garnet (YIG) films were prepared on Si substrates by Chemical Solution Deposition (CSD) technique using acetic acid and deionized water as solvents. Well-crystallized and crack-free YIG films were obtained when annealed at 750 °C and 850 °C respectively, showing a low surface roughness of several nanometers. When annealed at 750 °C for 30 min, the saturated magnetization (Ms) and coercive field (Hc) of YIG films were 0.121 emu/mm3 (4πMs = 1.52 kGs) and 7 Oe respectively, which were similar to that prepared by PLD technique. The peak-to-peak linewidth of ferromagnetic resonance (FMR) was 220 Oe at 9.10 GHz. The results demonstrated that CSD was an excellent technique to prepare high quality yttrium iron garnet (YIG) films on silicon, which could provide a lower-cost way for large-scale production on Si-based integrated devices.

Large transverse piezoelectric properties of lead-free Bi0.5(Na0.82K0.18)0.5TiO3 films

The ferroelectric and piezoelectric properties of Bi0.5(Na1-xKx)0.5TiO3 (x = 0, 0.18 and 0.25) films deposited on Pt(111)/TiO2/SiO2/Si(100) substrates using a chemical solution deposition technique were examined as part of an ongoing study into the development of lead-free piezoelectric films. The effective transverse piezoelectric coefficient (e∗31,f) was examined to assess the potential applications of these piezoelectric films for device applications using the Bi0.5(Na0.82K0.18)0.5TiO3 (BNKT18) cantilever, which is the morphotropic phase boundary composition in the Bi0.5(Na1-xKx)0.5TiO3 system. The BNKT18 cantilever showed good linearity of piezoelectric displacement with low hysteresis under an applied field, and exhibited a high effective transverse piezoelectric coefficient (e∗31,f) of ∼5.15 C/m2 and a figure of merit ((e∗31,f)2/ε0εr) of 3.8 GPa, which are comparable to the preferred oriented lead-free piezoelectric and lead zirconate titanate thin films. This suggests that the BNKT18 film is a potential candidate for lead-free piezoelectric film devices.

Simultaneous achievement of high dielectric constant and low temperature dependence of capacitance in (111)-oriented BaTiO3-Bi(Mg0.5Ti0.5)O3-BiFeO3 solid solution thin films

The temperature dependence of the capacitance of (111)c-oriented (0.90–x)BaTiO3-0.10Bi(Mg0.5Ti0.5)O3-xBiFeO3 solid solution films is investigated. These films are prepared on (111)cSrRuO3/(111)Pt/TiO2/SiO2/(100)Si substrates by the chemical solution deposition technique. All the films have perovskite structures and the crystal symmetry at room temperature varies with increasing x ratio, from pseudocubic when x = 0–0.30 to rhombohedral when x = 0.50–0.90. The pseudocubic phase shows a high relative dielectric constant (εr) (ranging between 400 and 560 at room temperature and an operating frequency of 100 kHz) and a low temperature dependence of capacitance up to 400°C, while maintaining a dielectric loss (tan δ) value of less than 0.2 at 100 kHz. In contrast, εr for the rhombohedral phase increases monotonically with increasing temperature up to 250°C, and increasingly high tan δ values are recorded at higher temperatures. These results indicate that pseudocubic (0.90–x)BaTiO3-0.10Bi(Mg0.5Ti0.5)O3-xBiFeO3 solid solution films with (111) orientation are suitable candidates for high-temperature capacitor applications.

Influence of Aliovalent Doping on Dielectric Properties of Ba0.6Sr0.4TiO3 Thin Film for Voltage Tunable Applications

Ba0.6Sr0.4TiO3 thin film with aliovalent doping of acceptor nature at ‘A’ lattice sites of ABO3 structure were prepared by a metal organic solution deposition (MOSD) technique on low loss quartz substrate. Oxide thin film having perovskite structure, namely, lanthanum nicklate (LaNiO3), also deposited using chemical solution deposition technique (CSD), was used as conductive bottom electrode. Solution properties and deposition process parameters were optimized for crack-free, uniform and smooth, pure and doped BST films on LNO electrode. The structural and microstructural analyses of the film were done using X-ray diffraction (XRD) and atomic force microscopy (AFM). Dielectric properties of the deposited film were studied using C-V and C-F electrical characterizations. The results indicate high tunability of 46%, very low loss tangent of 0.0065 with corresponding figure of merits of 71 for 2% K doped BST films at 1 MHz. The considerable improvement of dielectric properties of doped films compare to pure BST film is due to combined effect of perovskite lattice matched conductive bottom electrode and optimum doping level. These films had moderate dielectric constant, very low loss with good tunability which is suitable for tunable microwave applications.

SmBa2Cu3O7−δ superconducting layer prepared on NiO buffer layer through fluorine-free chemical method

With energy shortage becoming increasingly severe, the application of high-temperature superconducting material is a considerable prospects, where economic, efficient and energy-saving preparation technology becoming the key factors for the large-scale applications of [Formula: see text] (REBCO) superconducting coated conductors. Currently, non-vacuum chemical solution deposition technique is an important way to reduce the cost of preparation of coated conductors. However, a randomly oriented NiO growth is an important problem for the non-vacuum chemical preparation of superconducting coated conductor. A simple and valid method is to prepare textured NiO film on the bare nickel (Ni) tape. In this paper, NiO films with [Formula: see text]-axis texture were prepared in air and in argon respectively by the surface oxidation epitaxial method. We obtained the smooth and densification NiO films. The layer of [Formula: see text] was fabricated on the NiO film via a fluorine-free chemistry method. The purpose of this paper is to provide a potential value of non-vacuum chemical solution deposition technique for preparation of REBCO superconducting coated conductors.

Low Temperature Synthesis of Sub-micrometer Yttria-doped Barium Zirconate Thin Films by Modified Chemical Solution Deposition Technique

Presently research on proton conducting ceramic fuel cell (PCFC) has gained momentum for its low temperature (400 - 600°C) operation; one among the major governing factors for the successful low temperature operation is high ionic conductivity of electrolyte at low temperature. The state of the art protonic ceramic electrolytes are yttria doped barium cerate (BCY) and yttria doped barium zirconia (BZY). Although BCY shows very high protonic conductivity, it shows poor chemical stability in CO2-containing atmosphere. On the other hand, BZY has good chemical stability, but it has little lower protonic conductivity (1 x 10-2 S/cm at 450°C); however, it is sufficient for fuel cell operation. Fabrication of BZY components requires high temperature heat treatment. The major impediments to the fabrication of BZY electrolyte are deviation of stoichiometry due to Ba evaporation at high sintering temperature and the presence of barium carbonate (BaCO3) as impurity; these two factors drastically reduce conductivity of BZY. As per the literature report, sintering temperature for BZY is not less than 1400°C with long sintering time of minimum 5 hrs. This sintering temperature has been achieved with the help of sintering aids such as copper oxide, zinc oxide, etc. The presence of sintering aid also hampers the conductivity of BZY because of the second phase formation and/or segregation of sintering aid at the grain boundaries, thereby leading to low total protonic conductivity. In order to deal with these major issues, in the present research work we have demonstrated a fabrication procedure based on modified chemical solution deposition (CSD) technique of BZY thin film and low temperature sintering strategy without any sintering aid. Thin film reduces the ohmic resistance to the flow of ions in electrolyte, thereby enhancing the performance of PCFC. We have developed an acetate-based solution for thin film fabrication. The solution possesses good wettability to slicon nitride (Si3N4) substrate, thereby eliminating the issue of delamination. Drying control chemical agent (DCCA) was added to the solution in order to prevent crack formation during shrinkage of the film upon heat treatment. The solution is stable for more than three months, as evidenced by Fourier transform infrared spectroscopy (FTIR). The green film was formed on the substrate by spin coating. Subsequently, it was heat treated and sintered at 800°C for 2 hrs with special heat treatment schedule. The special heat treatment strategy involved sintering of BZY film in the amorphous stage due to delayed crystallization. The crystallization was delayed because of slower kinetics of pyrolysis as compared to the heating rate. Following this method, a dense and crack free sintered film was produced; no delamination from the substrate was observed. As per x-ray diffraction profile, the film was phase pure pervskite material without any trace of BaCO3. The novelty of this process lies in the lowest sintering temperature ever reported along with phase pure perovskite BZY. This process also eliminates the detrimental issues such as Ba evaporation and presence of second phase. The method is cost effective and requires less time. Therefore, this thin film fabrication procedure can be promising technique for commercial production of PCFC. Figure 1

Development of crack free BLT thick films by chemical solution deposition technique

Crack free (Bi3.25La0.75Ti3O12) BLT film of ~1μm thickness was deposited on Pt/Si(100) wafer by sol–gel methodology using a polymeric additive: polyvinyl pyrrolidone. The remnant polarization and coercive field values measured from the P–E hysteresis loops for BLT films annealed at 650°C and 700°C were 10μC/cm2, 110kV/cm and 11.5μC/cm2, 111.5kV/cm, respectively. The leakage current in the BLT film was remarkably low up to an electric field of 150kV/cm for which the measured leakage current density was 2.5×10−6A/cm2. The leakage current behavior showed Ohmic conduction in the low-field region and was dominated by space charge in the high-field region.

All chemical solution deposition of textured YBa2Cu3O7−x/Y0.2Ce0.8O2/La2Zr2O7 multilayer films on biaxially textured NiW tape

Biaxially textured La2Zr2O7 (LZO) single buffer layer, Y0.2Ce0.8O2 (YCO) single buffer layer, and YCO/LZO bilayer buffer layer are prepared on NiW tapes using chemical solution deposition technique. All the buffer layers are of good in-plane and out-of-plane texture. The introduction of a YCO cap layer on the LZO buffer layer improves the surface quality of the films. YBa2Cu3O7−x (YBCO) films are then prepared on these buffer layers using our recently developed low-fluorine solution route. Purely c-oriented YBCO films with good in-plane and out-of-plane texture are obtained on the YCO/LZO bilayer buffer layers. The YBCO/YCO/LZO/Ni stack prepared using all chemical solution routes shows a high Tc over 90 K, a sharp transition temperature ΔT = 0.8 K, and a Jc of 0.7 MA cm−2(at 77 K, 0T).

Low Temperature Synthesis of Sub-micrometer Yttria-doped Barium Zirconate Thin Films by Modified Chemical Solution Deposition Technique

Yttria-doped barium zirconate (BZY) electrolyte films with sub-micrometer thickness were prepared using a modified chemical solution deposition (CSD) technique at very low sintering temperature of 800 °C without sintering aid. Pure perovskite BZY phase without barium carbonate associated with low calcination temperature was successfully obtained with no obvious barium (Ba) evaporation to deviate the stoichiometry composition. This cost effective and scalable method for BYZ as compared to the other reported vacuum-based thin film deposition techniques such as pulsed laser deposition (PLD) or atomic layer deposition (ALD) are potentially applicable in the fabrication of high quality electrolyte for nano-thin film micro solid oxide fuel cells operating at temperature below 500 °C.

Ferroelectric properties and the origin of the magnetism in the Bi6Fe2Ti3O18 thin films

The Fe-containing Aurivillius phase Bi6Fe2Ti3O18 (BFFT) thin films were successfully prepared using the chemical solution deposition technique. The microstructure, ferroelectricity, and magnetic properties were investigated. A defined hysteresis loop was obtained with the remnant polarization (2Pr) 22.6 μC/cm2 at 2 kHz under the electric field ~600 kV/cm. The frequency dependence of hysteresis loops was also studied to exclude contribution of the leakage current to polarization in BFFT thin film. Furthermore, the electromechanical responses of the films were investigated using piezoresponse force microscopy. These results indicate the intrinsic ferroelectricity in the present BFFT films. It was found that the BFFT film shows room-temperature weak ferromagnetism with the saturated magnetization (Ms) ~2.9 emu/cm3. To explore the origin of the observed weak ferromagnetism, the magnetism of the same stoichiometric ceramics and the films was compared. The BFFT ceramics show antiferromagnetic interaction background, while the magnetism of the BFFT film may originate from the spin canting of the coupling of the Fe3+-based and Fe2+-based sublattices. The existence of Fe2+ ions in the BFFT films was also proved by the XPS spectrum.

Structural Transition in Thickness Dependent CSD Grown Nanostructure Manganite Thin Films

In this report, manganite thin films of La0.7Sr0.3MnO3(LSMO) of various thicknesses are carried out by using Chemical Solution Deposition (CSD) technique on(100)– oriented single crystalline LaAlO3(LAO) substrate. Desired film thickness was achieved via control of the number of deposition sequences. X-ray diffraction (XRD) study shows that 1stand 3rdcoatings of LSMO films have the cubic structure while 5thand 7thcoatings of LSMO films have hexagonal structure. As the film thickness increases, increase in lattice parameter(c)was observed. Surface morphological study was carried out using Atomic Force Microscopy (AFM). RMS roughness and grain size were found to increase with the thickness. It is interesting and noticeable that the structural transition occurs from cubic to hexagonal are clearly observed through XRD and AFM results. In electrical resistivity measurement, show the resistivity of all the samples decreases as the film thickness or grain size increases, but the trend inverts for the film with 7 coatings and the maximum MR with the value of 21.35 %, in Hexagonal structure.

Precursor evolution and growth mechanism of BTO/YBCO films by TFA—MOD process

In this study, BaTiO3 (BTO)-doped YBCO films are prepared on LaAlO3 (100) single-crystal substrates by metal—organic decomposition (MOD) using trifluoroacetate (TFA) precursor solutions. The critical current density (Jc) of BTO/YBCO film is as high as 10 MA/cm2 (77 K, 0 T). The BTO peak is found in the X-ray diffraction (XRD) pattern of a final YBCO superconductivity film. Moreover, a comprehensive study of the precursor evolution is conducted mainly by X-ray analysis and μ-Raman spectroscopy. It is found that the TFA begins to decompose at the beginning of the thermal process, and then further decomposes as temperature increases, and at 700 °C BTO nanoparticles begin to appear. It suggests that the YBCO film embedded with BTO nanoparticles, whose critical current density (Jc) is enhanced, is successfully prepared by an easily scalable chemical solution deposition technique.

Optimization of excess Bi doping to enhance ferroic orders of spin casted BiFeO3 thin film

Multiferroic Bismuth Ferrite (BiFeO3) thin films with varying excess bismuth (Bi) concentration were grown by chemical solution deposition technique. Room temperature multiferroic properties (ferromagnetism, ferroelectricity, and piezoelectricity) of the deposited BiFeO3 thin films have been studied. High resolution X-ray diffraction and Raman spectroscopy studies reveal that the dominant phases formed in the prepared samples change continuously from a mixture of BiFeO3 and Fe2O3 to pure BiFeO3 phase and, subsequently, to a mixture of BiFeO3 and Bi2O3 with increase in the concentration of excess Bi from 0% to 15%. BiFeO3 thin films having low content (0% and 2%) of excess Bi showed the traces of ferromagnetic phase (γ-Fe2O3). Deterioration in ferroic properties of BiFeO3 thin films is also observed when prepared with higher content (15%) of excess Bi. Single-phased BiFeO3 thin film prepared with 5% excess Bi concentration exhibited the soft ferromagnetic hysteresis loops and ferroelectric characteristics with remnant polarization 4.2 μC/cm2 and saturation magnetization 11.66 emu/g. The switching of fine spontaneous domains with applied dc bias has been observed using piezoresponse force microscopy in BiFeO3 thin films having 5% excess Bi. The results are important to identify optimum excess Bi concentration needed for the formation of single phase BiFeO3 thin films exhibiting the improved multiferroic properties.

Structural, ferroelectric, and optical properties of Pb0.60Ca0.20Sr0.20TiO3, Pb0.50Ca0.25Sr0.25TiO3 and Pb0.40Ca0.30Sr0.30TiO3 thin films prepared by the chemical solution deposition technique

Perovskite ferroelectric Pb0.60Ca0.20Sr0.20TiO3, Pb0.50Ca0.25Sr0.25TiO3 and Pb0.40Ca0.30Sr0.30TiO3, thin films were deposited on Pt/Ti/SiO2/Si and (100) LaAlO3 substrates by a chemical solution deposition method. XRD revealed the formation of pure thin films on both substrates. All thin films have very flat surfaces, and no droplets were found on their surfaces. Raman data showed a gradual phase transition from tetragonal to a pseudocubic perovskite structure in these thin films; a simultaneous increase in Ca and Sr contents at room temperature was also observed. Temperature-dependent dielectric permittivity measurements revealed a decreasing ferroelectric-to-paraelectric phase transition temperature with increasing Ca and Sr contents. At 100kHz, ferroelectric-to-paraelectric phase transition temperatures were approximately 505, 355 and 290K for Pb0.60Ca0.20Sr0.20TiO3, Pb0.50Ca0.25Sr0.25TiO3 and Pb0.40Ca0.30Sr0.30TiO3 thin films, respectively. The Eg of the films were estimated from Tauc׳s law and were found to be inversely dependent on the Ca and Sr content amounts.