Simple Chemical Solution Deposition Research Articles

Simple chemical solution deposition of Al2O3 dielectric layers for low-cost fabrication of transparent electronic devices

Simple chemical solution deposition of Al2O3 dielectric layers for low-cost fabrication of transparent electronic devices

Understanding the impact of Bi stoichiometry towards optimised BiFeO3 photocathodes: structure, morphology, defects and ferroelectricity.

BiFeO3 thin films have been widely studied for photoelectrochemical water splitting applications because of its narrow bandgap and good ferroelectricity which can promote the separation of photo-generated charges. Bismuth is well known as a volatile element and excess bismuth is usually added into the precursor to compensate the loss of bismuth during heat treatment, but the amount of excess bismuth required and how excess bismuth will affect PEC performance have not been clearly studied. Herein, self-doped Bi1+x FeO3 thin films are prepared via simple chemical solution deposition method with excess bismuth from 0-30% in the precursor. The loss of bismuth after annealing is confirmed by EDX and XPS. Multiple factors were investigated and it was found that non-stoichiometric Bi resulted in changes of structure, morphology, defects, electronic properties and PEC performance. An enhanced photocurrent is observed in bismuth-rich BiFeO3 films, which can be ascribed to the larger grain size, decreased oxygen vacancies, lattice distortion and supported charge separation. Moreover, the photocathodic performance can be further enhance by ferroelectric poling. Our work indicates that deficient bismuth should be carefully avoided during heat treatment and moreover, a slight excess of Bi is beneficial for PEC performance. Therefore, we offer a simple way to enhance PEC performance of BiFeO3-based ferroelectric materials through careful control of their stoichiometry.

Sol-gel synthesis and Opto-electrical properties study of double perovskite oxide Dy2NiMnO6 thin film

Thin film of double perovskite oxide Dy2NiMnO6 (DNMO) has been synthesised by the simple and cost-effective chemical solution deposition technique. The room temperature X-ray diffraction pattern and Raman spectroscopy confirm the monoclinic (space group - P21/n) crystal structure of polycrystalline DNMO thin film. The optical and electrical properties of DNMO thin film are investigated to study the detailed photo physical properties of DNMO thin film. The direct band gap and temperature dependant impedance spectroscopy confirm its semiconductor behaviour. Impedance spectroscopy also shows two types of dielectric relaxation behaviour and the nature of conductivity reveals the electron hopping conduction mechanism. Moreover, the chemical solution deposited DNMO film shows promising photo response under white light.

Highly efficient solar-light-driven photocatalytic degradation of pollutants in petroleum refinery wastewater on hierarchically-structured copper sulfide (CuS) hollow nanocatalysts

The high solar-light-driven activity of HS-CuS-HNCs was ascribed to its narrow band gap, strong visible-light absorption and high quantum efficiency characteristics, and especial the synergistic effect between HS-CuS-HNCs and H 2 O 2 . • HS-CuS-HNCs were prepared in high yield by a simple method at room temperature. • HS-CuS-HNCs showed high solar-light-driven activity. • The synergistic effect led to produce more reactive oxygen species (ROS). • The capabilities of ROS to reduce COD followed the sequence: •O 2 − > 1 O 2 > •OH. • A novel nanophotocatalyst was provided for utilizing solar energy efficiently. Hierarchically-structured CuS hollow nanocatalysts (HS-CuS-HNCs) were prepared in high yield (>95%) by a simple chemical solution deposition method at room temperature, and then used to photocatalytically degrade pollutants in petroleum refinery wastewater (PRW) under solar light radiation. Compared to bulk-size CuS catalyst, HS-CuS-HNCs with narrower band gap (E g = 0.96 eV) exhibited strong visible-light absorption, highly enhanced quantum efficiency and large specific area (101.5 m 2 g −1 ) characteristics. HS-CuS-HNCs showed significantly enhanced activity for the degradation of pollutants under both artificial and real solar light source (about 66% of COD in PRW was removed in 3 h degradation under conditions of 1.0 g/L catalyst and 7.6 pH). The activity of HS-CuS-HNCs was drastically enhanced further in the presence of hydrogen peroxide (H 2 O 2 ) (98% of COD in PRW was removed in 2 h under conditions of 1.0 g/L catalyst, 3.0 g/L H 2 O 2 and 7.6 pH), which was attributed to the synergistic effect between HS-CuS-HNCs and H 2 O 2 , leading to the enhanced quantum efficiency and production of more reactive oxygen species (ROS). Radical-quenching experiments revealed that the contributions of ROS to COD reduction in PRW followed the sequence: superoxide anion (•O 2 − ) > singlet oxygen ( 1 O 2 ) > hydroxyl radical (•OH). Important factors such as catalyst dose, H 2 O 2 dose and initial pH had influences on the degradation efficiency. This work provided a hierarchically-structured non-TiO 2 -based nanophotocatalyst with high performance for efficiently utilizing solar energy to oxidatively degrade pollutants in PRW fast and deeply.

Deposition of Super-Hydrophobic Silver Film on Copper Substrate and Evaluation of Its Corrosion Properties

A simple and versatile chemical solution deposition process is reported to manipulate the wettability properties of copper sheets. The whole process has the advantage of being time-saving low cost and environment-friendly. An adherent silver coating was achieved under optimal conditions. Scanning electron microscopy and X-ray diffraction were used to examine the silver film structure. A confocal microscope was used to record the 3D topography and assess the film roughness of the surface. A dual morphology was revealed, consisting of broad regions with feather-like structured morphologies and some areas with spherical morphologies. Such silver-coated copper samples exhibited a sufficiently stable coating with superhydrophobicity, having a maximum water contact angle of 152°, along with an oleophilic nature. The corrosion behavior of the produced hydrophobic copper under optimal conditions was evaluated by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) using a 3.5% NaCl solution. The corrosion protection mechanism was elucidated by the proposed equivalent circuits, indicating that the superhydrophobic silver coating acted as an effective barrier, separating the Cu substrate from the corrosive solution. The superhydrophobic coating demonstrated enhanced anti-corrosion properties against NaCl aqueous solution in relation to the copper substrate as indicated from both EIS and potentiodynamic polarization experiments.

Efficacy of hydrothermally grown ASnO3 (A-Ca, Sr, Ba) transparent conducting oxide thin films

ASnO3 (A-Ca, Sr, Ba) nanostructured thin films were grown on corning glass substrates without seed layer via hydrothermal route. Structural and morphological characterisations confirmed phase purity, high crystallinity and uniform deposition of the films. Cost effective TCO, which has comparable optical and electrical properties of ITO has been the motivation of the current study. Bandgap (3.02–3.31 eV), transparency (>82%), conductivity (8.37 × 102 to 3.33 × 103 S/cm) and figure of merit values (0.8–6.04 × 10−3 Ω-1) of ASnO3(ASO) films suggest that they could be useful for several optoelectronic applications. The materials developed in this work are made up of non-toxic as well as earth abundant elements and the thin films are deposited by simple chemical solution deposition method.

Chemical Solution Deposition of La-Substituted BiFe0.5Sc0.5O3 Perovskite Thin Films on Different Substrates

In the present work, polycrystalline Bi0.67La0.33Fe0.5Sc0.5O3 thin films were synthesized using a simple and cost-effective chemical solution deposition process employing the spin coating technique. In order to check the feasibility of the fabrication of thin films on various types of substrates, the films were deposited on Pt-coated silicon, silicon, sapphire, corundum, fused silica and glass. Based on the results of thermogravimetric analysis of precursor and thermal stability study, it was determined that the optimal annealing temperature for the formation of perovskite structure is 600 °C. It was observed that the relative intensity of the pseudocubic peaks (001)p and (011)p in the XRD patterns is influenced by the nature of substrates, suggesting that the formed crystallites have some preferred orientation. Roughness of the films was determined to be dependent on the nature of the substrate.

Bipolar resistive switching behavior and conduction mechanisms of composite nanostructured TiO2/ZrO2 thin film

In this work, TiO2/ZrO2 bilayer thin film was prepared on fluorine doped tin oxide (FTO)/glass substrates by using a simple and low-cost chemical solution deposition method. Reproducible bipolar resistive switching (RS) characteristics in Au/TiO2/ZrO2/FTO/glass devices are reported in this work. TiO2/ZrO2 bilayer thin films prepared in this work shows reversible bipolar resistive switching and unidirectional conduction performances under applying voltage and these special performances of TiO2/ZrO2 bilayer thin films was first reported. Obvious resistive switching performance can be observed after setting a compliance current, the ratio of high/low resistance reached about 100 at a read voltage of +0.1V and −0.1V and the RS properties showed no obvious degradation after 100 successive cycles tests. The resistive switching characteristics of Au/TiO2/ZrO2/FTO/glass device can be explained by electron trapping/detrapping related with the vacancy oxygen defects in TiO2/ZrO2 bilayer thin film layer. According to slope fitting, the main conduction mechanisms of the sample are Ohmic and Space charge limited current mechanism.

Epitaxial superconducting δ-MoN and δ-NbN thin films by a chemical solution deposition

Epitaxial superconducting δ-MoN and δ-NbN thin films, exhibiting a superconducting transition temperature (Tconset) of 13 K and 10.3 K, respectively, were prepared by a simple chemical solution deposition on c-cut Al2O3 substrates. A sharp transition and the large residual resistivity ratio (RRR) ρ300K/ρonset of δ-MoN and δ-NbN thin films suggest high quality of the prepared epitaxial thin films. The critical current density (Jc) under 100 Oe at 5 K is of 1.37 and 0.74 MA/cm2 for the δ-MoN and δ-NbN thin films, respectively. The results will provide a facile route to prepare epitaxial superconducting metal nitride thin films.

Introducing a thin MnO2 layer in Co3O4-based memory to enhance resistive switching and magnetization modulation behaviors

Nanocrystalline bilayer composite MnO2/Co3O4 thin films were fabricated by a simple chemical solution deposition method to investigate the resistive and magnetization switching properties. Compared with pure Co3O4 thin films device, bilayer MnO2/Co3O4 thin films device exhibits enhancement in resistive switching (RS) and magnetization modulation, such as uniform SET and RESET voltages, stable cycle-to-cycle switching endurance (>2 × 103 cycles), good data retention time (>104 s), and RS induced magnetization switching (∼63%). Through the analysis of fitting current-voltage (I–V) curves and temperature-dependent resistance, it demonstrated that Schottky emission conduction is dominated at high resistance state of the devices. Enhancement in RS performance can be attributed to the growth and dissolution of confined conductive filaments which are composed of Mn atoms and oxygen vacancies, evidenced by temperature dependence and magnetization switching at different resistance states. The physical relevancy between RS and magnetic switching involves in the creation and annihilation of conductive filaments, associated with the reversible conversion of cation valence state (Co2+ and Co3+, Mn ions and Mn atoms). Results suggest that by introducing a thin MnO2 inserting layer, Co3O4 based device shows promising applications for nonvolatile RS memory and multifunctional electromagnetic coupling device.

Tuning the defects and luminescence of ZnO:(Er, Sm) nanoflakes for application in organic wastewater treatment

A series of ZnO nanoflakes modified with rare earth ions of Er and Sm were prepared by a simple chemical solution deposition approach. It was found that the doping content of rare-earth ions was dominant for the defects in the nanoflakes and the ability of photocatalytic degradation for rhodamine B (RhB). The ZnO:(Er, Sm) nanoflakes exhibited a superior photocatalytic activity compared to undoped ZnO mainly due to the longer lifetime of photogenerated electrons-hole pairs in the process of photocatalytic reaction, and Zn0.98Sm0.01Er0.01O nanoflakes could degrade 96.5% RhB within 60 min under UV light irradiation. PL results provided a strong evidence for the existence of VO defect, which was also found to be responsive for the enhanced photocatalytic activity of ZnO:(Er, Sm) nanoflakes. And the peaks at 515 nm and 550 nm could be attributed to the transitions of $$^{2} H_{11/2} \to^{4} I_{15/2}$$ and $$^{4} S_{3/2} \to^{4} I_{15/2}$$ from Er3+ ions, indicating the realization of green luminescence.

Defect and dopant induced room temperature ferromagnetism in Ni doped ZnO nanoparticles

ZnO nanoparticles were doped with Ni by simple chemical solution deposition method. All the synthesized nanoparticles crystallize in the wurtzite ZnO structure. The UV–Visible absorption measurement shows broad absorption band in the visible range around 440 nm, 618 nm and 660 nm which are d-d transitions characteristic of Ni2+ within the tetrahedral symmetry. Compared to higher doping concentration, 1% Ni doped sample shows higher magnetic moment at room temperature with a saturation magnetization of 0.0123 emu/g. The coercivity of 365 Oe for the 1% doped sample reduces to 217 Oe for 5% Ni doped sample. Fourier Transform Infrared Spectroscopy (FTIR) measurement shows the consistent formation of the characteristic E2 mode in ZnO even after Ni doping and is supported by the Raman measurements. The incorporation of Ni dopant in the ZnO host lattice is further confirmed by X-ray Photoelectron Spectroscopy (XPS) measurement. The prominent visible luminescence in the undoped sample is quenched due to doping as observed from luminescence measurements. Magnetic measurements were also done in the doped samples after annealing. Systematic studies on structural, optical & magnetic measurements reveal that the nature of defects as well as Ni2+ ions are responsible for the magnetic moment obtained at room temperature.

Growth, Microstructures, and Optoelectronic Properties of Epitaxial BaSn1–xSbxO3−δ Thin Films by Chemical Solution Deposition

Epitaxial thin films of perovskite BaSn1–xSbxO3−δ are fabricated by a simple chemical solution deposition method, and the relationship among the processing, the microstructure, and the optoelectronic property is systematically investigated. The process of multiple annealing combined with the postannealing under nitrogen ambient is the optimal procedure to fabricate high quality BaSnO3−δ thin films. Sb doping in Sn sites facilitates the epitaxial growth of the BaSnO3−δ grains. The Hall results show that with increasing Sb doping content the carrier density and the carrier mobility are enhanced and decreased, respectively, resulting in the highest room-temperature electrical conductivity of 260 S/cm in the BaSn0.91Sb0.09O3−δ thin film. It is confirmed that the ionized Sb5+ and oxygen vacancies are the main scattering sources for carrier transport in BaSn1–xSbxO3−δ thin films. The results will provide guidance for synthesis of BaSnO3−δ-based and other donor-doped perovskite transparent conducting large-area ...

Growth of tungsten oxide nanostructures by chemical solution deposition

Tungsten oxide nanostructures were fabricated on LaAlO3 (00l) substrates by a simple chemical solution deposition. The decomposition behavior and phase formation of ammonium tungstate precursor were characterized by thermal analysis and X-ray diffraction. Moreover, the morphology and chemical state of nanostructures were analyzed by scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectra. The effects of crystallization temperature on the formation of nanodots and nanowires were investigated. The results indicated that the change of nanostructures had close relationship with the crystallization temperature during the chemical solution deposition process. Under higher crystallization temperature, the square-like dots transformed into the dome-like nanodots and nanowires. Moreover high density well-ordered nanodots could be obtained on the substrate with the further increase of crystallization temperature. It also suggested that this simple chemical solution process could be used to adjust the nanostructures of tungsten oxide compounds on substrate.

Enhancement of Polarization in Ferroelectric Films via the Incorporation of Gold Nanoparticles.

Ferroelectric thin films have been extremely studied for many applications such as nonvolatile memories, super capacitors, and solar cells. For these devices, improving the polarization properties of ferroelectric thin films is of great significance to their performance. Here, Au–lead zirconate titanate (PZT) nanocomposite thin films were prepared by a simple one-step chemical solution deposition (CSD) method on silicon substrates, and the effects of Au concentration on the ferroelectric properties were investigated. The experimental results show that the remanent polarization of the Au–PZT films with 1.2 mol % Au is about 80 μC/cm2, which is 50% higher than that of the pure PZT thin films. On the basis of the analysis of chemical valences, the enhanced polarization properties can be ascribed to the interaction between Au nanoparticles (Au NPs) and PZT at the Au–PZT interfaces. Our results demonstrate that the incorporation of an appropriate amount of Au NPs is an effective way to enhance the polarization properties of ferroelectric films. The Au–PZT nanocomposite thin films with excellent polarization properties on silicon substrates are expected to be widely used in integrated ferroelectric devices.

Facile and Cost Effective Synthesis of Oxide-Derived Silver Catalyst Electrodes via Chemical Solution Deposition for CO2 Electro-Reduction

Electrochemical CO2 reduction to useful fuels is a promising strategy for the sustainable energy production. However, because CO2 reduction reaction involves sluggish kinetics, the development of high performing catalyst is a first priority for the success in this system. Herein, cost effective fabrication of oxide-derived silver catalyst for CO2 electro-reduction was successfully prepared by simple chemical solution deposition involving the following steps: (i) spin-coating of precursor solution, (ii) oxidation by air-annealing, and (iii) electrochemical reduction. The prepared silver catalyst achieved 83.7% of CO Faradaic efficiency at − 1.19 VRHE with an outstanding mass activity of 465.04 A g− 1 which was originated from the unique features of the catalyst as well as precursor solution. With the introduced fabrication method, the precursor solution containing relatively low silver concentration was preferred to form small silver particles, resulting in high catalytic activity. We anticipate the developed method to be widely applied for the preparation of oxide-derived metal catalysts and metal alloy nanostructured catalysts in advanced CO2 conversion system.

Simple Solution Deposition of Co3O4 on FTO for Rapid and Selective Nonenzymatic Glucose Detection

There is no permanent treatment for diabetes mellitus yet. This condition is managed by regularly checking blood glucose levels and taking appropriate measures accordingly. Hence, a significant amount of research efforts have been made to develop highly sensitive and affordable glucose sensor. It is well known that the performance of any sensor is highly dependent on the nature and fabrication techniques used for the preparation of the electrodes. Various electrode fabrication techniques such as pulsed laser deposition (PLD), plasma sputtering, atomic layer deposition (ALD), hydrothermal, electrodeposition, electrospinning have been used to fabricate various metal oxide based electrodes for glucose sensing applications. These techniques are not suitable for commercial scale production of economical nonenzymatic glucose sensor. In this study a simple chemical solution deposition process has been used to fabricate Co3O4 electrode as an electrocatalyst for nonenzymatic oxidation of glucose. Several physical and chemical characterisation techniques such as XRD, HRSEM, HRTEM,AFM, EIS, EELS, EDS was used to elucidate the phyiscal and chemical characteristics of the Co3O4 electrode. The as prepared electrode showed fast response time (< 7s), good sensitivity (504.1 µA mM-1cm-2), high selectivity towards glucose at an applied potential of +0.60V in 0.1 M NaOH solution. A detection limit of 3 µM (S/N = 3) was measured for the Co3O4 electrode. The electrode retained 85% of initial current response after 2 months of application. Figure 1 presents the electrochemical performance of the Co3O4 electrode in the presence and absence of 1mM glucose at a scan rate of 25 mVs-1. Figure 1

Magnetoelectric studies on CoFe2O4/0.5(BaTi0.8Zr0.2O3)-0.5(Ba0.7Ca0.3TiO3) lead-free bilayer thin films derived by the chemical solution deposition

Lead-free multiferroic bilayer thin films were fabricated on (111)Pt/Si substrate via a simple sol-gel chemical solution deposition, by altering the position of piezoelectric (Ba0.85Ca0.15) (Ti0.9Zr0.1)O3 (BCTZO) and ferromagnetic CoFe2O4 (CFO). Single layer BCTZO experiences the out-of-plane compressive stress, while this layer is under tensile strain in both the bilayers. The microstructural study confirms the formation of bilayers with expected chemical composition composed of multiple well-developed crystallites having no crystallographic dependencies. Thin films of BCTZO and CFO/BCTZO exhibited saturated ferroelectric hysteresis loops at room temperature with a Pr of 7.2 and 5.6 μC/cm2. The magnetic field induced shift in phonon vibrations coupled with direct magnetoelectric (ME) measurements demonstrated a stress-mediated coupling mechanism in the bilayers. We found a superior ME coefficient (105 MV/cm Oe) and dielectric tunability (∼52%) for CFO/BCTZO bilayer compared to the BCTZO/CFO bilayer, which demonstrates that the modification of strain state in bilayers is useful for the desired ME coupling. The BCTZO having piezoelectricity on par with that of lead-based ones can be useful to tailor lead-free ME applications.

Influence of Zr/Ti atomic ratio and seed layer on the magnetoelectric coupling of Pb(ZrxTi1−x)O3 film-on-CoFe2O4 bulk ceramic composites

Lead zirconate titanate Pb(ZrxTi1−x)O3 films with various Zr/Ti ratios of 20/80, 40/60, 52/48, 60/40 and 80/20 are deposited on highly dense CoFe2O4 ceramics using a simple chemical solution deposition. All Pb(ZrxTi1−x)O3 films are polycrystalline and have no preferential orientations. The dielectric, ferroelectric, piezoelectric and magnetoelectric properties strongly depend on the Zr/Ti ratio. And the Pb(ZrxTi1−x)O3 films with a Zr/Ti ratio close to morphotropic phase boundary exhibit best properties, whose magnetoelectric coefficient is over 1.5 times larger than those of other Zr/Ti ratios. The introduction of a PbO seeding layer between the Pb(Zr0.52Ti0.48)O3 films and CoFe2O4 substrates facilitates the (100)-texture. Therefore, the magnetoelectric coefficient was enhanced by 1.5 times. The further improvement of the magnetoelectric coupling could be anticipated by fabricating Pb(Zr0.52Ti0.48)O3 films with more or absolute (100)-texture and using conductive interfacial layer between two phases.

Water Oxidation by Manganese Oxide Electrocatalytic Films Synthesized by Chemical Solution Deposition Method

Water splitting catalyzed by low cost and earth abundant material is critically important issue in mass production of hydrogen from water using electrical energy. In this study, we developed highly efficient manganese oxide (MnOx) electrocatalytic films by a simple chemical solution deposition (CSD) method for oxygen evolution reaction (OER). Specifically, the MnOx electrocatalytic films were synthesized at different annealing temperatures at 350, 450, and 550°C after the precursor solution coating on fluorine-doped tin oxide (FTO) glass substrates. The MnOx electrocatalytic film prepared at 450°C has exhibited the most catalytic activity for OER with the overpotential of 387 mV at 10 mA/cm2 in 1 M NaOH alkaline solution. We suggested that this high OER activity of MnOx electrocatalytic film arise from the higher surface area, richer Mn3+ state on the catalysts surface, and low charge transfer resistance between electrocatalytic film and electrolyte based on electrochemical surface area (ECSA), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS) analysis.