Nebulizer Spray Pyrolysis Research Articles

Effect of gadolinium on tin oxide thin films prepared by nebulizer spray pyrolysis method

Gadolinium-doped tin oxide (SnO2: Gd) thin films were prepared by the nebulizer spray pyrolysis technique on glass substrates using tin (IV) chloride pentahydrate (SnCl2·5H2O) and Gadolinium Sulphate Octahydrate as source materials. Different wt % of doping such as (0%, 1%, 2% and 3%) Gadolinium was used to prepare the spray solution, and their effects on structural, morphological, optical, properties were investigated. X-ray diffraction patterns revealed the polycrystalline tetragonal structure of prepared films. The crystallite size value varies due to Gd doing level. SEM images demonstrated well-aligned tetragonal-shaped nano-grains. Optical band gap values were estimated to be in the range of 3.78–3.82 ​eV by Tauc’s plot. The effects of Gd doping level on the SnO2 thin films obtained using an excitation wavelength of 350 ​nm exhibit emission peaks centered at 361 ​nm, 496 ​nm, 520 ​nm, 540 ​nm and 594 ​nm respectively. It’s indicated that SnO2 thin films exhibited a broad dominant peak near 396 ​nm (about 3.14 ​eV). Raman spectroscopy indicates the spectra for as deposited SnO2 is dominated by presence of strong and sharp peak at 2434 ​cm−1 along with the peak of smaller intensity at 482 ​cm−1.

Yttrium - Substituted SnO2 thin films and its gas sensing activity against NH3 gas: Characterization and sensitivity evaluation

Pure and yttrium-doped tin oxide (SnO2:Y) thin film was successfully coated on a glass substrate using a nebulizer spray pyrolysis technique with a constant temperature of 400 °C. Coated films are characterized by a variety of techniques like XRD, SEM with EDX, TEM, elemental mapping, UV, PL, and gas sensors. All XRD film patterns demonstrate a well-defined polycrystalline phase, which fits well with the SnO2 tetragonal rutile structure. Surface morphology analysis revealed that the surface roughness of the SnO2:Y thin films increased with an increase in yttrium concentration. Transmission Electron Microscopy and SAED findings result suggested that the SnO2:Y thin films were highly crystalline. The optical band gap (3.66 eV–3.81 eV) rises due to Y- doping points the credibility of SnO2 thin films. Photoluminescence (PL) spectroscopy revealed a large number of oxygen vacancies in SnO2:Y films. The PL intensity varies with the doping concentrations. The gas sensing capability of nanostructured films was compared to the concentration of Y-doping and NH3 concentrations from 25 ppm to 125 ppm. For the SnO2:Y(5 wt.%) film, a significant response with short response time and recovery time (23 s, 7 s) to 25 ppm NH3 is observed at room temperature. The yttrium loaded SnO2 sensor is indeed a promising candidate for NH3 detection.

Transparent conducting SnO2 thin films synthesized by nebulized spray pyrolysis technique: Impact of Sb doping on the different physical properties

The impact of antimony (Sb) doping concentration on the different physical properties of transparent conducting tin oxide (SnO2) thin films synthesized through nebulized spray pyrolysis (NSP) method have been explored systematically. X-ray diffraction (XRD) results reveal the tetragonal cassiterite structure of single phase SnO2 and the decrement of crystallite size with rising Sb doping concentration. Uniform and compact surface morphology with continuous distribution of grains and reduction of grain size with increasing dopant amount are illustrated by scanning electron microscopy (SEM). The stoichiometry of SnO2 film with 2% Sb doping is confirmed by energy dispersive X-ray spectroscopy (EDS) study. The optical transmittance is more than 85% in the visible region for undoped film and enhanced in the near infrared (NIR) spectral region for all the films. The transparency is reduced and the optical band gap is found to increase from 3.69 eV to 3.90 eV upon Sb inclusion. The extinction coefficient, refractive index, dielectric constant, dissipation factor, volume energy loss function, surface energy loss function, optical conductivity and optical density of the films are determined and interpreted for different dopant concentrations. The photoluminescence (PL) spectrum demonstrates the enhancement of emission intensity with increasing Sb incorporation representing its suitability in the application of solid state lighting. The lowest resistivity of 6.435 × 10−4 Ω cm and the highest carrier concentration of 1.316 × 1021 cm−3 are achieved for the film with 8% Sb doping concentration. The mobility of the studied degenerated films is varied from 54.743 cm2/Vs for undoped films to 7.378 cm2/Vs for 8% Sb doped film and limited by ionized impurity scattering. The film deposited with 2% Sb doping level exhibits the highest figure of merit values in both visible and NIR wavelength region indicating its better role in optoelectronic applications.

Scandium: An efficient dopant to modulate the optical spectrum of vanadium dioxide (VO2)

Transparency of VO2 thin films in the visible region is an important aspect of study for its use in smart window applications. In this regard, we experimentally validate the theoretical prediction regarding the influence of scandium (Sc) doping on modulating the optical spectrum of VO2. Sc-doped nano-crystalline VO2, bulk and thin films were synthesised using a two-step process involving a rapid non-equilibrium solution combustion process and ultrasonic nebulised spray pyrolysis of aqueous combustion mixture respectively; followed by a reduction step. The presence of Sc was determined by X-ray photoelectron spectroscopy where a peak observed at 530.06 eV is attributed to Sc–O interaction. Raman spectra showed a shift in 611 cm−1 peak position to a lower wavenumber due to tensile strain arising from Sc doping. Sc-doped VO2 thin films showed semiconductor to metal transition of four orders of magnitude change in resistance. Sc-doping increased the band gap from 1.76 eV for undoped to 2.02 eV with 2.0 at. % of doping thereby making the films more transparent in the visible region of the optical spectrum. This shift in the band gap of VO2 was consistent with the theoretical reports. Thus, Sc is a potential dopant for modulating the optical spectrum of VO2 for its application in smart windows.

Improved optoelectronic properties of Terbium co-doped CdO:Zn thin films coated by nebulizer spray pyrolysis method

Abstract Terbium co-doped CdO:Zn thin films have been coated by the facile and an efficient spray pyrolysis technique on the substrate of glass to tune its optical and electrical properties. From XRD analysis, all the diffraction peaks strongly exhibit polycrystalline nature with perfect cubic structure followed by preferential orientation was changed from (111) plane to (200) plane. The nature of the crystal structure and crystallite size is reduced from 20.4 to 16.5 nm by increasing Tb doping concentration due to defects in the lattice. The atomic force microscope AFM mages clearly show that the film's grain size decreases with the Tb dopant. The elements such as Cd, Zn, O, and Tb exists in the elemental mapping and EDS spectra. The transmittance is varied from 70, to 82% at 800 nm, and the maximum bandgap of 3.06 eV is observed for 1.5 wt.% degenerate doping concentration. PL emission at 435 nm shows a high intense peak attribute to the crystalline quality of the film. The electrical property of the film has been greatly improved with doping concentration, which is useful for optoelectronic devices. The TCO based on the 1.5 wt.% Tb co-doped CdO:Zn film shows an improved performance (higher transmission of 82%, lowest resistivity of 7.48 × 10−4 Ω cm, the highest carrier concentration of 11.3×1020 cm−3). These results propose a much simpler route to achieve high-quality Terbium co-doped CdO:Zn thin films for TCO applications.

Structural, morphological and opto-electrical properties of transparent conducting SnO2 thin films: Influence of Sb doping

ABSTRACT Pure and antimony doped tin oxide (Sb:SnO2) thin solid films were synthesised through a simple and low-cost nebulised spray pyrolysis (NSP) route. The influence of Sb doping on the different physical properties of these films was systematically investigated. The results of X-ray diffraction (XRD) study exhibited polycrystalline in nature of all films with tetragonal cassiterite structure of single phase SnO2. XRD analysis also revealed the reduction in crystallite size as well as the grain size observed in scanning electron microscopy (SEM) with Sb doping concentration. The average transmittance of all the films was greater than 73% at the visible wavelength region and the transparency was reduced by Sb inclusion. The direct optical band gap value was the lowest of 3.94 eV for pure SnO2 and enhanced by Sb doping level. The effects of Sb doping concentration on extinction coefficient, refractive index, dielectric constant, optical conductivity and optical density of the films were examined. Photoluminescence spectrum revealed a broad violet emission peak near 390 nm and Sb doping intensified the peak. Both the resistivity and sheet resistance were found to vary in the range of 1.61 × 10−3 Ω.cm to 3.92 × 10−4 Ω.cm and 32.73 Ω/□ to 134.41 Ω/□, respectively with the variation of Sb doping concentration. The highest mobility and carrier concentration were 54.74 cm2/Vs and 7.02 × 1021 cm−3 for undoped and 10% Sb doped films, respectively. However, the figure of merit was found to be maximum of 1.38 × 10−3 (Ω/cm2)−1 for 5% Sb doping concentration among the films.

Impact of substrate temperature on the properties of yttrium oxide thin films prepared by nebulizer spray pyrolysis technique

In this study, the yttrium oxide (Y2O3) thin films were prepared at different substrate temperatures (Tsub) 300 °C, 350 °C, 400 °C, 450 °C, and 500 °C by nebulizer spray pyrolysis technique. Structural studies confirm the formation of Y2O3 in the cubic phase. The trap rock structure was obtained from the SEM micrograph. It was observed that the yttrium oxide thin films show better particle growth at higher substrate temperatures. XRD results reveal that the crystalline nature of the Y2O3 thin films increased with the increasing of substrate temperatures, and the SEM morphology grain size will decrease in higher temperatures, which is good agreement with the XRD results. The optical bandgap varied from 2.58 to 3.6 eV among an increased substrate temperature from 350 °C to 500 °C. The recorded photoluminance spectra of Y2O3 thin films exhibit a sharp and broad emission at 310 nm and 466 nm.

Effect of source material of g-C3N4 on the photocatalytic activity of ZnO/g-C3N4 thin film coated on stainless steel mesh substrate

In this study,four sets of ZnO/g-C3N4 films were deposited using four different source materials of g-C3N4 (urea, thiourea, melamine and dicyanamide)onto stainless steel meshes using tubular nebulizer spray pyrolysis technique. The structural, surface morphological, functional group and optical properties of the deposited films were examined using X-ray diffractometry (XRD), Scanning Electron Microscopy (SEM), FTIR spectroscopy, spectrofluorometry (PL) and diffuse reflectance spectroscopy (DRS) characterization techniques, respectively. The effect of precursor of graphitic carbon nitride on the photocatalytic activity of ZnO/g-C3N4 film was investigated by employing the prepared films as catalysts for the degradation of methylene blue (MB) and malachite green (MG) dyes. It was found that the sample ZnO/gU exhibits superior photocatalytic activity compared to other samples. The degradation efficiency was found to be 98% and 97% for MB (75 min) and MG (45 min) dyes, respectively. The role of precursor of g-C3N4 for the enhancement of photocatalytic activity of ZnO/g-C3N4 is analyzed with supporting experimental evidences.

Structural, morphological, vibrational, optical, and nonlinear characteristics of spray pyrolyzed CdS thin films: Effect of Gd doping content

This paper reports the preparation of cadmium sulfide (CdS) thin films using a nebulizer spray pyrolysis technique by varying gadolinium content in the range of 0–5 wt.%; their characterization is also described. In this study, the effect of Gd concentration on structure, vibrational, optical linear, and nonlinear properties is investigated. The XRD examination of undoped and Gd-doped CdS films shows the crystalline nature toward the (002) plane. Other important parameters, such as crystalline size (D), strain (ϵ), and dislocations density (δ), were evaluated by XRD, and these results are thoroughly discussed. The SEM studies show the morphology of grains. It was observed that the size of grains increased with an increase in doping concentration. Owing to Gd doping in CdS, the optical energy gap is observed to be lower than that of pure film, which is in the range of 2.416–2.283 eV. The linear and nonlinear properties of CdS: Gd films indicated that Gd doping affected optical properties. The observed enhancement in opto-electrical properties, changes in crystalline quality, and optical property enhancements are caused by an increase in Gd doping concentration.

Impact of Substrate Temperature on the Properties of Rare-Earth Cerium Oxide Thin Films and Electrical Performance of p-Si/n-CeO2 Junction Diode

In this work, we report a p-Si/n-CeO2 junction diode fabricated by a cost-effective and large-area deposition technique of jet nebulizer spray pyrolysis. The n-CeO2 layer was coated on four different substrate temperatures (Tsub) 350, 400, 450, 500 °C and their properties were studied by various techniques like XRD, FE-SEM with EDX, UV–Vis and I–V characterization. XRD pattern confirmed a cubic fluorite crystalline phase of CeO2 thin films with preferential growth along (2 0 0) direction. A smooth surface with inter-connected smaller grains was recorded by FE-SEM micrographs and also the existing elements Ce and O have been confirmed. For Tsub of 450 °C, an exceptional optical absorption with smaller band energy of 3.3 eV was recorded in the UV–Vis spectrum. The electrical conductivity results indicated that all the films are semiconducting in nature. I–V characteristics of all the fabricated diode showed better rectification in dark with excellent photovoltaic characteristics under light exposed condition. The photosensitvity of the diode varied from 21.94 to 1093.75% with substrate temperature. Our results strongly suggested that rare-earth based p-Si/n-CeO2 diodes are suitable for future applications in ultraviolet photo-detector and photo-diode.

High Photoresponsive p-Si/n-In2O3 Junction Diodes with Low Ideality Factor Prepared Using Closely Packed Octahedral Structured In2O3 Thin Films

Octahedral indium oxide thin films with different precursor concentrations of 0.05, 0.075, 0.1 and 0.125 M were coated on glass substrates at 450 °C using jet nebulizer spray pyrolysis technique. Surface morphology of the prepared samples showed closely packed octahedrons for all concentrations. The measured root-mean-square value of the films was varied between 40.45 and 188.98 nm with increased precursor concentrations. From optical analysis, the calculated optical band gap was continuously decreased with increase in precursor concentrations. A slight blue shift was recorded through the PL spectrum while increasing the precursor concentration due to the oxygen vacancies. The nature of electrical conductivity of the In2O3 films was analysed. Interestingly, we have calculated two types of activation energies in the In2O3 films one is corresponding to low temperature and another is higher temperature. Further, p-Si/n-In2O3 junction diodes are fabricated with different precursor concentrations. Particularly, the 0.075 M of p-Si/n-In2O3 junction diode recorded a minimum ideality factor of n = 2.64 under light exposed condition, confirming the photo-conducting nature of the diodes in visible wavelength range.

Alkaline and rare-earth metals doped transparent conductive tin oxide thin films

In this paper, Ba-doped SnO2 (SnO2:Ba), Mg-doped SnO2 (SnO2:Mg) and Ce-doped SnO2 (SnO2:Ce) nanostructured thin films were prepared on the glass substrate via a simple and low-cost nebulizer spray pyrolysis method. The crystal structure and morphology of all the samples were investigated by X-ray diffraction (XRD) and field-emission-scanning electron microscopy (FE-SEM), respectively. XRD results suggest that all the samples are polycrystalline with the tetragonal rutile structure. FE-SEM analysis exhibits a uniform surface morphology with homogenous distribution of grains. The transmittance measurement suggests that SnO2:Ba sample exhibits high transparency above 90% in the visible region. We find that doping causes an increase in the band gap, this behavior is explained by the Burstein–Moss effect. Two emission bands in the ultraviolet and visible regions are observed in the photoluminescence spectra. Hall effect measurement reveals that all the samples are degenerate and exhibit n-type semiconducting nature with carrier concentration in the order of 1018 cm−3. Ba doping induces the lowest resistivity of 0.047 Ω·cm associated with an increase in carrier concentration of 8.38 × 1018 cm−3 and mobility of 15.87 cm2 V−1 s−1. In contrast, the incorporation of Mg and Ce in SnO2 reduces the mobility and conductivity, which may be associated with the grain boundary scattering.

Investigation of structural, optical and photoluminescence properties of nanostructured BaxSn1-xO2 thin films: An effect of Ba doping

In this work, alkaline Ba doped SnO2, BaxSn1-xO2 (0.00 ≤ x ≤ 0.05), thin films have been synthesized by a cost-effective nebulizer spray pyrolysis method. X-ray diffraction analysis reveals that undoped and Ba doped SnO2 films are polycrystalline with tetragonal rutile structure. Field emission scanning electron microscopy analysis shows a morphological transformation of the crystallite grains from pyramidal-shaped to cubic-shaped. 3% Ba doped SnO2 sample exhibits excellence properties such as minimum resistivity (3.10 × 10−3 Ω cm), high mobility (21.47 cm2 V−1s−1) and maximum visible transmittance (86% at 550 nm). The optical band gap is estimated to be 4.04, 3.92, 3.89 and 4.10 eV for the samples prepared with Ba contents of 0, 1, 3 and 5%. In the photoluminescence investigation, a dominant blue emission band at ~ 474 nm is observed in the SnO2, whereas Ba doped SnO2 samples exhibit a strong violet emission band at ~ 430 nm. These emission bands can be attributed to the presence of defect-related states inside the band gap of SnO2.

Methanol solvent effect on photosensing performance of AZO thin films grown by nebulizer spray pyrolysis

Dopant concentration variation or solvent change is commonly used for the growth and characterization of doped metallic thin films. In contrast, we have studied the effects of varying methanol solvent volume ratio for aluminum doped zinc oxide (AZO) thin film growth. AZO thin films were coated on glass and ITO substrates by nebulizer spray pyrolysis method. The effect of different solvent concentrations and the water to methanol ratio on the resultant film properties were analyzed. The structural and lattice constants of the prepared films were investigated by x-ray diffraction (XRD). Pure methanol solvent enhances the structural quality of the AZO film, as confirmed from the XRD and x-ray photoelectron spectroscopy analyses. The atomic force microscopy images showed thinner and smooth film surface for the pure methanol solvent condition without water. The optical absorption study showed a high transmittance (∼93%) in the visible region with a bandgap of 3.30 eV, which is close to bulk ZnO (3.36 eV). The photoluminescence spectra showed a powerful UV emission at 390 nm, indicating that the films were of good quality. Ag/AZO/Cu2O/ITO structured photodiodes were fabricated using ITO substrate and their photosensing properties were studied. All the prepared films (S1, S2, S3, S4 and S5) showed an increase in current level for both dark and light conditions, with an increase in methanol solvent ratio. The film S5 (pure methanol solvent) under the dark and light illumination conditions at a bias of 1.0 V, showed current values of ∼6.5 × 10–5 A and ∼1.85 × 10–4 A, respectively.

Comprehensive Study on Nebulizer-Spray-Pyrolyzed Eu-Doped PbS Thin Films for Optoelectronic Applications

PbS films in undoped state and with various Eu contents (1 wt.%, 3 wt.%, and 5 wt.%) have been coated effectively on insulating glass substrates by a nebulized spray pyrolysis route. The effects of Eu doping on various properties including the photosensitivity of the PbS films were systematically analyzed. X-ray diffraction (XRD) analysis of the materials revealed a polycrystalline nature with crystallites showing simple cubic structure oriented along (200) direction. Based on the XRD data, the crystallite size, dislocation density, and lattice strain of the films with different doping concentrations were calculated and are consistently discussed. The secondary phase Eu3O4 formed when the Eu doping level was higher in the host solution. The Raman peaks detected at 190 cm−1, 236 cm−1, and 465 cm−1 confirmed formation of PbS. Scanning electron microscopy was used to reveal the morphology of the films as a function of the dopant concentration. Important optical properties including the bandgap, absorption coefficient, dielectric constant, index of refraction, and coefficient of extinction of the films are systematically reported. Optical study of the films revealed a variation of the bandgap from 2.14 eV to 2.81 eV with increasing Eu doping level. The 3 wt.% europium-doped PbS film showed better photosensitivity at 100 W/m2 compared with the other films based on current–voltage (I–V) measurements.

Room temperature ammonia gas sensor using Nd-doped SnO2 thin films and its characterization

Nd-doped SnO2 thin films are prepared by the nebulizer spray pyrolysis method. The compositional and morphological studies are discussed. The X-ray diffraction reveals that the films are polycrystalline in nature. The grain size increases as the doping concentration of Nd increases. The x-axis orientation of the films is enhanced by Nd doping. The intensity of the miller indices (200) is enhanced due to doping. In the Raman spectrum, the doping concentration-dependent intensity is observed. The quenching is observed in the photoluminescence spectrum. The transmittance and the band gap of films have been decreased due to doping. The 5 wt% Nd-doped film shows the maximum response to ammonia.

Praseodymium doped PbS thin films for optoelectronic applications prepared by nebulizer spray pyrolysis

Simple nebulizer spray technique used pristine and rare earth praseodymium (Pr) doped PbS thin films coated on soda-lime glass and their optoelectronic properties are reported. Dopant concentration-dependent structural, morphological, optical, and electrical properties of the prepared films were analyzed using X-ray diffraction, Raman spectrum, scanning electron microscopy, EDAX, UV–visible spectrum. X-ray diffraction study revealed the growth of polycrystalline face-centered cubic PbS thin films without any impurities. Increase of doping concentration resulted in a decrease in peak intensity indicating the degradation of crystalline quality. The Raman peaks observed at 190, 240 and 464 nm justified the formation of PbS phase. Surface morphology of the films showed dopant concentration dependent compact and uniform distribution of grains on substrate. EDAX studies legitimized the existence of Pb, S, and Pr in the prepared films. Energy band gap values of the films were gradually increased from 2.18 to 2.69 eV for the increase of doping concentration from 0 to 5 wt%. The prepared films exhibited increased currents for the increase of doping concentration with reasonable photosensing effect in I–V measurements.

Investigation of the Optical, Morphological and Thermal Properties of Carbon Nanotubes Synthesized by Nebulized Spray Pyrolysis

Multiwalled carbon (C) nanotubes (CNTs) were synthesized by nebulized spray pyrolysis of xylene and ferrocene in a horizontal tube furnace at atmospheric pressure. The reaction temperature and the ...

Investigations on copper zinc tin sulfide thin films grown through nebulizer assisted spray pyrolysis technique

An attempt is made in this work to synthesize the nontoxic Cu2ZnSnS4 (CZTS) thin film on FTO coated glass substrates through aerosol assisted nebulizer spray pyrolysis technique at different annealing temperatures for photovoltaic energy conversion. The deposited thin film is further used to form a heterojunction interface with a cadmium sulfide layer to fabricate a solar cell with Glass/FTO/CdS/CZTS/Ag superstrate structure to reveal its photovoltaic application. Various characterization techniques are utilized to study its inherent properties. X-ray diffraction (XRD) is employed to investigate the structural parameters such as crystallite size, microstrain and dislocation density which shows a preferential peak for (112) plane around 28.5° confirming the formation of kesterite CZTS. Raman measurements establish the peak for CZTS at 336 cm−1 and confirm the absence of parasitic secondary phases for an excitation wavelength of 488 nm. Scanning electron microscope and atomic force microscope used to examine the surface morphology and roughness of the films reveal a good surface morphology with a grain size of 555.9 nm and roughness of 123.7 nm for an annealing temperature of 350°C. The bandgap of the deposited CZTS films is found to be around 1.5 eV. The I-V characteristics of CZTS seem to be better for the 350°C annealed film. The performance of the optimized CZTS absorber layer is tested by forming a solar cell structure. The devised solar cell exhibited an open circuit voltage of 213 mV and a short circuit current density of 490 μA cm−2 with a conversion efficiency of 0.68% substantiating the usage of the prepared film as an absorber for photovoltaic conversion.

Investigation of erbium co-doping on fluorine doped tin oxide via nebulizer spray pyrolysis for optoelectronic applications

Novel nebulizer spray pyrolysis method was used to prepare erbium (Er) and fluorine co-doped tin oxide (FTO) films with doping concentration (0.5, 1, 1.5 wt.%). The effect of Er on FTO were analyzed by various characterization tools. XRD studies revealed tetragonal crystal structure with polycrystalline nature and crystallize size decreasing with Er concentration. AFM studies confirmed the smoothness of the films. Photoluminescence study revealed the emission peaks in UV and visible region. Transmittance, carrier concentration and carrier mobility are more in case of 1.5 wt.% doping concentration confirms the prepared films are opting for optoelectronic devices.