Sol-gel Spin-coating Technique Research Articles

Tuning room-temperature TCR of La0.7K0.3− xSrxMnO3 (0.00 ≤ x ≤ 0.3) films by K and Sr co-occupying A-site

A series of La0.7K0.3−xSrxMnO3 (0.00 ≤ x ≤ 0.3) films were fabricated on LaAlO3 substrates using a sol-gel spin-coating technique. The relationship between electrical transport properties and a microstructure was explained via the Jahn–Teller effect, a phenomenological percolation model, and a double-exchange mechanism. The results revealed the strong impact of K and Sr co-occupying A-sites on the formation of Mn3+/Mn4+ pairs, crystal structure, conductivity, surface morphology, and in-plane and out-of-plane strains. The as-fabricated La0.7K0.25Sr0.05MnO3 films showed a peak temperature coefficient of resistivity of 16.63% K−1 at 298.3 K.

Environmentally Benign Structural, Topographic, and Sensing Properties of Pure and Al-Doped ZnO Thin Films.

In the present research work, Zn1–xAlxO thin films with varying proportions of Al (x = 0.00, 0.01, 0.02, and 0.03) are prepared by a chemical sol–gel spin-coating technique. The crystal structural, morphological, and humidity-sensing properties of the synthesized Zn1–xAlxO thin films, with varying concentrations of Al (x = 0.00, 0.01, 0.02, and 0.03), were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM); a special humidity-controlled chamber was designed for the humidity-sensing studies. In structural and phase analyses, XRD patterns of Zn1–xAlxO thin films show a hexagonal wurtzite crystal structure. The average crystallite sizes of Zn1–xAlxO thin films were calculated and found to be ∼18.00, 22.50, 26.30, and 29.70 nm using the X-ray diffraction (XRD) pattern. The surface morphology of Zn1–xAlxO Al (x = 0.00, 0.01, 0.02, and 0.03) thin films obtained from AFM micrographs analysis indicates the modification of the spherical grains into nanorods, which were distributed throughout the surface of the films. The SEM image of 3 wt % Al-doped ZnO nanomaterials also shows that spherical nanoparticles changed to nanorod-like structures with a high packing density. Furthermore, increasing the Al-doping concentration from 0 to 3 wt % in ZnO NPs shows lower hysteresis loss, less aging effect, and good sensitivity in the range of 9.8–16.5 MΩ/%RH. The sensitivity of the sensing materials increased with increasing Al-doping concentration, which is very useful for humidity sensors.

Bi and Sn Doping Improved the Structural, Optical and Photovoltaic Properties of MAPbI3-Based Perovskite Solar Cells

One of the most amazing photovoltaic technologies for the future is the organic–inorganic lead halide perovskite solar cell, which exhibits excellent power conversion efficiency (PCE) and can be produced using a straightforward solution technique. Toxic lead in perovskite can be replaced by non-toxic alkaline earth metal cations because they keep the charge balance in the material and some of them match the Goldschmidt rule’s tolerance factor. Therefore, thin films of MAPbI3, 1% Bi and 0%, 0.5%, 1% and 1.5% Sn co-doped MAPbI3 were deposited on FTO-glass substrates by sol-gel spin-coating technique. XRD confirmed the co-doping of Bi–Sn in MAPbI3. The 1% Bi and 1% Sn co-doped film had a large grain size. The optical properties were calculated by UV-Vis spectroscopy. The 1% Bi and 1% Sn co-doped film had small Eg, which make it a good material for perovskite solar cells. These films were made into perovskite solar cells. The pure MAPbI3 film-based solar cell had a current density (Jsc) of 9.71 MA-cm−2, its open-circuit voltage (Voc) was 1.18 V, its fill factor (FF) was 0.609 and its efficiency (η) was 6.98%. All of these parameters were improved by the co-doping of Bi–Sn. The cell made from a co-doped MAPbI3 film with 1% Bi and 1% Sn had a high efficiency (10.03%).

Qualitative analysis of PZT (52/48) MPB using different synthesis methods

The current work reports a comparison between the structural and optical attributes of PZT (52/48) powder and thin film prepared via solid-state reaction and sol-gel spin-coating technique, respectively. The two obtained PZT samples, PZT-I corresponding to powder which was calcined at 875°C for 2 h, and PZT-II corresponding to a thin film which was annealed at 650°C for 2 h, were investigated via X-Ray Diffraction, Raman Spectroscopy, UV–Vis Spectroscopy, and SEM analysis. The diffraction spectra suggested the creation of a polycrystalline perovskite structure in both the samples. The optical band gap was evaluated using Tauc's relation. The bandgap values were found to be 3.2 eV for PZT-I and 3.87 eV for PZT-II. The bandgap values are significantly different for the PZT materials prepared by the two different methods.

Influence of boron addition on the phase transformation, microstructure, mechanical and in-vitro cellular properties of bredigite-type coatings deposited by a spin coating technique

Doped calcium silicates, e.g. bredigite (Ca7MgSi4O16) have recently become a growing interest in biomedicine thanks to outstanding biocompatibility, bioactivity, and improved mechanical properties when compared to calcium phosphate counterparts. Here, we have produced thin bredigite-type coatings on Ti6Al4V substrate by the polyvinyl alcohol (PVA) assisted sol-gel spin-coating technique and studied the influence of boron incorporation (0.5 and 1.0 mol) on the microstructural, phase, nanomechanical, and in-vitro cellular properties of deposited coatings. Chemical and structural analysis of the coatings was thoroughly performed by Focussed Ion Beam Scanning Electron Microscope (SEM/FIB), Atomic Force Microscopy (AFM), differential thermal analysis (DTA-TG), X-ray diffraction (XRD), and Fourier-Transform Infrared spectroscopy (FTIR), while the nanomechanical properties were evaluated by nanoindentation and nanoscratch tests. Overall, all deposited films were smooth and porous composed of ∼25–50 nm nanoparticles. The boron incorporation increased the coating thickness as a result of PVA interaction with borate ions. The nanomechanical properties (Young's modulus, nanohardness, critical load for cracking) decreased by the boron addition as a result of decreasing the strength of grain boundaries between the nanoparticles. The in-vitro contact cytotoxicity testing revealed high proliferation of the osteoblast cells in all coatings giving the potential of application in orthopedics.

Dependence of Structural and Optical Properties of ZnO Thin Films Grown by Sol–Gel Spin-Coating Technique on Solution Molarity

Dependence of Structural and Optical Properties of ZnO Thin Films Grown by Sol–Gel Spin-Coating Technique on Solution Molarity

Investigation of the Structural and Temperature Dependent Electrical Properties of Mzno (M = CE and Sm) Schottky Diode Devices Fabricated Using the Sol-Gel Spin Coating Technique

Investigation of the Structural and Temperature Dependent Electrical Properties of Mzno (M = CE and Sm) Schottky Diode Devices Fabricated Using the Sol-Gel Spin Coating Technique

OPTICAL STUDY OF SOL-GEL SPIN-COATING TiO2/Si3N4 MULTILAYERS ON GLASS SUBSTRATES

In this work, we have adopted a sol-gel spin-coating technique and prepared alternative TiO2/Si3N4 multilayers on glass substrates. These alternating layers of TiO2/Si3N4 thin film samples were calcinated at two different temperatures and studied for their optical performance. The optical properties of fabricated thin films were investigated by UV-Visible spectrophotometer, X-ray diffractometer (XRD), Fourier transform infrared (FTIR), and Raman spectroscopy. UV-visible spectra showed broader and higher optical reflectance in the visible spectral region. FTIR transmission spectra show Ti-O-Ti and Si-N stretching modes at around 600 and 881 cm-1. XRD pattern confirmed the presence of anatase-TiO2 and α-Si3N4 phases. Finally, Raman spectra revealed the presence of anatase-TiO2 and N-Si vibration modes.

Optical and structural investigations of TiO2 multilayers on glass prepared via sol–gel spin-coating technique

Titanium di-oxide (TiO2) multilayer thin films were deposited on glass substrates by using sol–gel spin-coating technique. The TiO2 thin film coatings were varied from two- to six layers and each layers calcinated at 600°C for 1 hour. The prepared samples were characterized by UV–visible spectrophotometer (UV–Vis), Fourier transform infra-red (FTIR) spectroscopy and X-ray diffractometer (XRD) techniques. The UV–Vis spectra showed the highest reflectance with the effect of six (6L) layers of TiO2 thin films as compared to the two- (2L) and four (4L) layers of thin films. The XRD patterns revealed the anatase-TiO2 phase with six layers of TiO2 and amorphous-TiO2 nature confirmed by two and four layered films. The obtained results proved that the use of enhanced multilayers (6L) of TiO2 thin films were effectively improved the quality of film crystallinity (8.3 nm) and corresponding optical performance as compared to reduced layers.

Large temperature coefficient of resistivity (TCR) of La1-xCaxMnO3 films prepared by spin-coating method

La1-xAxMnO3 (A = alkaline-earth or alkali metal) perovskites with large temperature coefficient of resistivity (TCR) offer immense opportunity for the application in high-performance infrared bolometer. However, numerous studies have revealed that the manganite films with large TCR values are not easily obtained by various fabrication technologies. Herein, a facile sol-gel spin-coating technique was used to prepare La1-xCaxMnO3 (LCMO, 0.280 ≤ x ≤ 0.375) films. All the samples were highly oriented along the out-of-plane direction of La0.3Sr0.7Al0.65Ta0.35O3 (001) substrates. With the rise in Ca doping amount, the resistivity of the films first decreased, and then, increased. This change can be attributed to the competition between the carrier concentration and lattice distortion. The LCMO films displayed large TCR and low-field magnetoresistance (MR) values, which exceeded those of previously reported thin films. The maximum TCR and low-field MR values were observed at x = 0.330, reaching 30.13% K−1 (266.43 K) and 68.6% (270.08 K), respectively. The La0.67Ca0.33MnO3 film with large TCR and MR values presents potential for the applications in high-sensitivity infrared bolometers and magnetic sensors.

High room-temperature TCR and MR of La1-xSrxMnO3 thin films for advanced uncooled infrared bolometers and magnetic sensors

Perovskite manganese films had promising applications in the field of photoelectronic materials and devices. However, the utilization of manganese films remained severely challenging due to high fabrication cost and inferior electrical and magnetic properties. Herein, La1-xSrxMnO3 (LSMO) thin films were fabricated on La0.3Sr0.7Al0.65Ta0.35O3 (LSATO) substrates using a facile sol–gel spin-coating technique. All the LSMO films displayed (001)-orientation with orthorhombic structure. The LSMO films exhibited high temperature coefficient of resistivity (TCR) and magnetoresistance (MR) values at room-temperature. The maximum TCR value was 10.4 % K−1 (301.2 K, for x = 0.175). This result can be attributed to high carrier concentration and mobility of optimal × content LSMO films with low film-substrate lattice mismatch (-0.4%), leading to low resistivity, and thus, increased TCR value. The maximum MR value reached 42.85% (290.95 K, for x = 0.150). The LSMO films with high room-temperature TCR and MR values are potential materials for advanced uncooled infrared bolometers and magnetic sensors.

Physical Properties of Different Thicknesses ZnO Thin Films Prepared via Sol-gel Spin Coating Technique

This paper presents the investigation of the thickness of the ZnO thin films by varying the number of deposition layers during the spin coating deposition process. ZnO thin films were deposited with a different number of layers (ranging from 1, 3, and 5), and the main purpose of this study is to explore the effect of the thickness on the properties of ZnO thin films. The deposited thin films were characterised using field emission scanning electron microscope, surface profilometer, and X-ray diffraction. From the characterisation results, the morphology of the ZnO thin films changed significantly with the number of layers and their thickness value. As expected, the thickness increased as the number of layers increased. The crystalline quality of the deposited film improved as the thickness increased. A change in crystallographic orientation was also observed in which the thicker, thin films showed crystal growth in the (102) direction, whereas the thinner one was in the (101) direction. A slight increase in crystallite size for dominant orientation also was observed with the increase of film thickness.

Boosting near-infrared photoluminescence efficiency of erbium ions and ZnO quantum dots codoped amorphous silica thin films

Er3+ ions and ZnO QDs codoped amorphous silica thin films are prepared by the modified sol-gel spin-coating technique. By introducing the ZnO QDs as sensitizers, the PL emission intensity of Er3+ ions is enhanced by more than two orders of magnitude. With the increasing annealing temperature, the lengthening PL emission lifetime indicates the gradual passivation of the non-radiative trap states. The thermal quenching behavior of PL emission intensity is analyzed by the temperature-dependent PL spectra. With the increasing annealing temperature, the decrease of activation energy suggests the narrowing of energy level difference between the excited state of Er3+ ions and the defect state of ZnO QDs. The gradually improved phonon-assisted energy transfer efficiency results in the greatly enhanced PL efficiency of Er3+ ions. These results will be a starting point for further research on the sensitization mechanisms in the rare earth ions and wide-bandgap QDs codoped amorphous silica.

Ultrawide bandgap high near ultraviolet transparency amorphous Sn–Al co-doped ZnO thin films

Transparent amorphous Sn–Al co-doped ZnO thin films (a-SAZO) were prepared by sol-gel spin-coating technique. Sn was inserted with a constant concentration of 2 at.%, and Al was inserted with different concentrations of 1, 2, 3, 4, and 5 at.%. X-ray diffraction patterns indicate that the samples are amorphous. UV-visible spectrometry shows that a-SAZO thin films are a combination of two different amorphous phases; the dominant amorphous phase tends to simulate the amorphous feature and the ultrawide bandgap of the glass substrate, whereas the minor amorphous phase tends to take its proper amorphization and bandgap. The appearance of the dominant amorphous phase is due to the effect of the amorphous glass substrate leading to high near ultraviolet transparency and ultrawide bandgap in the range of 4.00–4.03 eV. The minor amorphous phase shows very low near ultraviolet transparency and bandgap from 3.08 to 3.16 eV. Thus, the control of the amorphous structure of thin films allows attaining the desired near ultraviolet transparency and bandgap. The lowest resistivity was found 6.71×10−3Ω cm for Sn 2 at.% - Al 5 at.% concentration. Amorphous tin-aluminum zinc oxide (a-SAZO) with low resistivity can alternate amorphous indium-gallium zinc oxide (a-IGZO).

The Influence of Different Stabilizers on Properties of Sol–Gel Spin-Coated Zinc Oxide Films

Zinc oxide (ZnO) thin films have been deposited onto fluorine-doped tin oxide substrates (FTO) using sol–gel spin-coating technique with different sol stabilizers. The effect of sol stabilizers on structural, morphological, optical, and photoelectrochemical properties of the ZnO films was investigated. XRD analysis shows that all ZnO films have a polycrystalline hexagonal wurtzite structure with a preferred growth orientation along the (101), and the average of crystallites size varies from 46,277 to 82,266 nm. Room temperature photoluminescence (PL) spectra indicate a UV emission at around 380 nm originated from nearby band-edge transitions. Also, we investigated the effects of sol-stabilizers on the photoelectrochemical (PEC) properties of all ZnO photoanodes, and the best photocurrent density was evaluated at around 1710–4 A cm−2. Finally, donor density and flat-band potential of the different ZnO elaborated photoanodes were deduced from the Mott-Schottky plots.

Aluminum Doping Contents Dependent Photoluminescence and Resistivity of ZnO Nanofilms

Using sol–gel spin-coating technique Al-doped ZnO nanofilms (AZONFs) were made on Si(100) substrates and characterized. The obtained nanofilms were annealed at 500 °C for 3 h in air. The effects of changing Al doping level (0 to 5 at%) on the structures, morphologies, electrical and photoluminescence characteristics of the nanofilms were evaluated. The XRD patterns of the AZONFs confirmed the formation of wurtzite hexagonal ZnO lattice with preferred growth along (101) lattice plane. In addition, the c-axis orientation of the AZONFs became weaker with the increase in Al doping contents. The surface morphologies, structures, electrical and optical properties of the AZONFs were found to be very sensitive to the Al contents changes. The nanofilm prepared with 1 at% of Al displayed lowest resistivity of 4.238 × 10−3 Ω.cm measured by the four-point probe method. The optical band gap energy (increased from 3.22 to 3.304 eV) and carrier mobility of the AZONFs were improved with the increase in Al contents. The proposed AZONFs may be advantageous for various high performance optoelectronic device applications.

Effect of lithium salt precursors on the physical properties of ZnO-Li thin films

Zinc oxide (ZnO) thin films were prepared on glass substrates with three different lithium salt precursors (acetate, chloride and nitrates) with Li/Zn atomic ratio varying between 0% and 20% using sol-gel deposition and spin-coating technique. The aim of the work was to compare the physical properties of lithium containing ZnO thin layers obtained using different Li salt precursors; in order to identify the most suitable one. The X-ray diffraction measurements showed that all 500°C annealed films were polycrystalline. The samples prepared from lithium nitrates solutions showed a preferred orientation along c-axis (002) and their crystallites sizes are much larger compared to other Li source. The ultraviolet-visible transmission spectra confirmed the good transparency of all ZnO films with an average transmission around 85 % in the visible range. The optical band gap values varied between 3.19 eV and 3.28 eV. All the results revealed that the ZnO-Li films prepared with LiNO3 exhibit the highest crystallographic quality and the best optical and electrical properties compared to C2H3LiO2 and LiCl containing precursors.

Synthesis of ZnO sol-gel thin-films CMOS-Compatible.

Zinc oxide (ZnO) is a II–VI group semiconductor with a wide direct bandgap and is an important material for various fields of industry and high-technological applications. The effects of thickness, annealing process in N2 and air, optical properties, and morphology of ZnO thin-films are studied. A low-cost sol–gel spin-coating technique is used in this study for the simple synthesis of eco-friendly ZnO multilayer films deposited on (100)-oriented silicon substrates ranging from 150 to 600 nm by adjusting the spin coating rate. The ZnO sol–gel thin-films using precursor solutions of molarity 0.75 M exhibit an average optical transparency above 98%, with an optical band gap energy of 3.42 eV. The c-axis (002) orientation of the ZnO thin-films annealed at 400 °C were mainly influenced by the thickness of the multilayer, which is of interest for piezoelectric applications. These results demonstrate that a low-temperature method can be used to produce an eco-friendly, cost-effective ZnO sol–gel that is compatible with a complementary metal-oxide-semiconductor (CMOS) and integrated-circuits (IC).

Synthesis of Tin Oxide Thin Layer by Doping Aluminum, Fluorine, and Indium Using Sol-Gel Spin Coating Technique

The synthesis of tin oxide thin films with doping aluminum, fluorine, and indium (SnO2: Al + F + In) by sol-gel spin coating technique has been successfully carried out. This synthesis aims to determine the quality of the thin film formed by adding doping aluminum, fluorine, and indium. The basic material used is SnCl2.2H2O, while the doping material used is AlCl3, NH4F, and InCl3.4H2O. The comparison of the basic ingredients and doping mixture of aluminum, fluorine and indium (SnO2: Al+F +In) used were 100: 0%, 95: 5%, 90: 10%, 85: 15%, 80: 20% and 75: 25%. The synthesis uses a glass substrate with size (10 x 10 x 3) mm. Coating synthesis includes substrate preparation, sol-gel making, film making, and sample heating. The layers that are made consist of 1 to 4 layers. The results showed that the layer formed had a high degree of transparency along with the increasing concentration of the doping material percentage. The higher the doping concentrations of aluminum, fluorine, and indium, the higher the transparency of the resulting layer. Besides, the greater the number of layers, the lower the transparency level of the layers

Influence of Bi3+ doping on microstructure and photoelectric properties of ZnO thin film

Bismuth (Bi) doped ZnO (BZO) thin films were successfully synthesized by sol-gel spin-coating technique. The effects of the concentration and photoelectric properties of the films were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), selected area electron diffraction (SAED) techniques, photoluminescence (PL) studies. The results showed that the successful doping of Bi3+ into ZnO lattice could produce more photo-generated carriers. The grain size of the film was decreased with the increasing of doping ratio. The photocurrent of 1% Bi3+ doped BZO thin film is 25% higher than that of pure ZnO thin film.