Tin oxide thin films deposited by ultrasonic spray pyrolysis

This study investigated microstructure of SnO₂ thin films deposited by ultrasonic spray pyrolysis technique using 0.2 M of SnCl₄·5H₂O in absolute ethanol as a precursor. The deposition temperature (350–450 °C) and time (20–90 min) were varied. The influence of film-deposition conditions on grain size and orientation were discussed. The deposited SnO₂ films were textured polycrystalline films. The preferred orientation of SnO₂ films were quantitatively evaluated by texture coefficient (TC). The mean grain size and film thickness determined by SEM could be controlled over a range of 50–325 nm and 80–2690 nm, respectively.     

Physical properties of spray deposited Ni-doped zinc oxide thin films

Transparent thin films of nickel doped zinc oxide were deposited on to corning glass substrates via chemical spray pyrolysis using zinc acetate and nickel nitrate as precursors. Structural, morphological, optical, electrical, dielectrical and impedance properties of the films as a function of nickel doping concentration as well as inter-particle interactions by complex impedance spectroscopy were investigated. The deposited films are polycrystalline with a hexagonal (wurtzite) crystal structure along (002) preferential orientation. The films are highly transparent in the visible region with a transmittance higher than 86%, and have an optical band gap ranging from 3.23 to 3.19 eV depending on the nickel doping concentration. The high electrical conductivity of doped films is explained on the basis of the presence of oxygen vacancies. Decrease of electrical conductivity due to nickel doping is explained on the basis of compensation of oxygen vacancies. The dielectric constant and loss tangent as a function of frequency are reported. Interparticle interactions in the deposited films are studied by complex impendence spectroscopy.     

Photoluminescence and third-order nonlinear optical limiting properties of Sn1-xNdxO2 thin films deposited via spray pyrolysis

In the present work, spray pyrolysis method was adopted to synthesis nano thin films of Sn_1-xNd_xO₂ (x = 0.01 to 0.1) possessing tetragonal structure with (1 1 0) plane orientation. Nd doping reduced the overall crystallinity of the films, however Sn_0.92Nd_0.08O₂ film showed crystallite size of 18.7 nm, similar to that of the pure film. The morphology changed to distinct grains at lower doping concentration, beyond which a fibrous nature evolved but again changed to smaller grains with further increase in the doping. The oxidation states of the constituent elements were confirmed using XPS. The transmittance of the films reduced due to incorporation of Nd ions. A decrease in the energy band gap was also noticed in the films following dopant addition. The PL emissions corresponding to the Nd ion transitions was found in the NIR region resulting from internal 4f-shell transitions of Nd³⁺ ions. Other defect related emissions like the one from oxygen vacancies also showed up in the UV and visible wavelength regions, which were responsible for a near white light emission. The third-order optical nonlinearity of the films was confirmed using the Z-scan technique. All the Sn_1-xNd_xO₂ films till 8 at. % of doping showed reverse saturable absorption. The highest and lowest nonlinear absorption coefficient was exhibited by Sn_0.92Nd_0.08O₂ and Sn_0.98Nd_0.02O₂ films, respectively. Depending on the Nd concentration, the films either showed self-focusing or self-defocusing behavior and influenced the nonlinear refractive indices of the films. The least optical limiting values among the doped films was obtained in the range of 1.73 kJ/cm² for Sn_0.92Nd_0.08O₂ films.     

Effect of structural defects,surface roughness on sensing properties of Al doped ZnO thin films deposited by chemical spray pyrolysis technique

In this article, the gas sensing properties of Al-doped ZnO thin films have been reported where the nanocrystalline ZnO based thin films were well deposited by a simple and inexpensive ‘chemical spray pyrolysis (CSP)’ technique. Films have been found to be uniform, pinhole free and well adherent to the substrate. The morphology, structures, and surface roughness of the deposited Al-doped ZnO thin films were studied by various types of characterization techniques. In addition, the authors have observed that the sensor response and selectivity towards CO gas is improved by the Al doping at a low operating temperature. XRD results showed that the obtained films are nanocrystalline in nature with hexagonal wurtzite phase. Further, the annealed films were used for detection of CO in the air and maximum response was observed at 175 °C. The improvement in sensor response of Al-doped ZnO thin films to CO gas attributed to the defect chemistry, crystallite size and surface roughness.     

Nanocrystalline ZnO films deposited by spray pyrolysis: Effect of gas flow rate

ZnO is one of the multifunctional metal oxide semiconductors suitable for use in optoelectronic devices, as an alternative to tin oxide and indium oxide. Undoped ZnO films have been prepared using simple and cost-effective spray pyrolysis technique. In this work, we present detailed analysis of the structural, morphological and optical properties of ZnO films. X-ray diffraction spectra of the films have shown that the films are polycrystalline and hexagonal wurtzite in structure. The average grain size, estimated from the (002) peak using the Scherrer formula is around 40 ± 5 nm. The average optical transmittance of undoped ZnO thin films was about 80% in the visible. The AFM analysis reveals the surface topology having highly rough nature. The enhanced extinction coefficient varies with the flow rate. The EDX spectrum registers non-stoichiometric ZnO growth with O and Zn in 28.46 and 71.56 at. %. The features of the ZnO lead to the visible light transmission and efficient charge transport.     

Electrochromism in spray deposited iridium oxide thin films

Electrochromic iridium oxide thin films were deposited onto fluorine doped tin oxide coated glass substrates from an aqueous iridium chloride solution by pneumatic spray pyrolysis technique. The as-deposited samples were X-ray amorphous. The electrochromic properties of thin films were studied in an aqueous electrolyte (0.5N H₂SO₄) using cyclic voltammetry (CV), chronoamperometry (CA) and spectrophotometry. Iridium oxide films show pronounced anodic electrochromism owing to Ir⁺⁴ ↔ Ir⁺³ intervalency charge transition. The reversibility of cyclic process in Ir oxide films is found to be higher, which increases with increasing number of colour-bleach cycles.     

Optoelectronic characteristics of YAG phosphor-incorporated ZnO films deposited by ultrasonic spray pyrolysis

This work presents a novel white light device. An yttrium aluminum garnet (YAG) phosphor-incorporated zinc oxide (ZnO) film is deposited on a slide glass substrate by ultrasonic spray pyrolysis. A nanoflower consisting of a hexagonal nanopetal is formed on the surfaces of the samples, and the sizes of the nanopetal are approximately 200 to 700 nm. Additionally, the nanopetal becomes blunted with an increasing incorporated amount of YAG. As the incorporated amount is 1.5 and 2.5 wt.%, the photoluminescence color of the YAG-incorporated ZnO film is nearly white, possibly contributing to the YAG emission and the band-to-deep level transition in the ZnO film.     

Structural, optical, electrical and photovoltaic electrochemical characterization of spray deposited NiWO4 thin films

The preparation of nickel tungstate (NiWO₄) thin film by spray pyrolysis (SP) with ammonical solution is presented. The phase and surface morphology characterizations have been carried out by X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis, respectively. The study of optical absorption spectrum in the wavelength range 350-850 nm shows the presence of direct as well as indirect band gaps in the material, respectively found to be 2.28 and 2.00 eV. The thin film material shows semiconducting behaviour and highly resistive at room temperature as evident from its dc electrical conductivity measurements obtained by the Two Point Probe method in the temperature range 310-500 K. The thin films deposited on fluorine doped tin oxide (FTO) coated conducting glass substrates are used as photoanode in photovoltaic electrochemical (PVEC) cell. The PVEC cell configuration is: NiWO₄|Ce⁴⁺, Ce³⁺|Pt; 0.1 M in 0.1N H₂SO₄. The PVEC characterization reveals the fill factor and power conversion efficiency to be 0.47 and 0.78%, respectively. The flat band potential is found to be −0.32 V (SCE).     

Porous indium oxide thin films deposited by electrostatic spray deposition technique

This paper presents the preparation process of porous indium oxide (In₂O₃) films using a novel deposition technique, i.e., electrostatic spray deposition (ESD). The films were deposited on platinum-coated alumina substrates using as precursor solution indium chloride in ethanol and acetic acid. The films were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. The nanocrystalline structure of the films was evidenced by TEM and also by XRD studies. The Raman spectroscopy and XRD measurements revealed the cubic phase of In₂O₃ films. Considering the obtained results, we conclude that the ESD technique is an efficient, cheap and successful method for the preparation of porous indium oxide films.     

Synthesis of WO3 thin films by surfactant mediated spray pyrolysis

WO₃ thin films were prepared by surfactant mediated spray pyrolysis deposition on fluorine-doped tin oxide (FTO) conductive glass using hexadecylthymethylammonium bromide (HTAB) as structure-directing agent. The crystalline structure, topography, electrical conductivity and optical properties were investigated as function of cationic surfactant concentration. High transparency and conductivity were obtained for the sample which contained the lowest amount of surfactant (50 ppm) in the spraying solution. Significant changes in the morphology were observed with increasing HTAB addition level; samples lost their homogeneity and porosity, while the layer roughness increased. The surfactant by-products resulted after annealing were investigated based on FTIR analysis and a decomposition scheme was proposed. The modified surface composition and morphology influenced the hydrophilic character of the samples.     

Effect of precursor concentration on structural,morphological and opto-electric properties of ZnO thin films prepared by spray pyrolysis

Sprayed ZnO films were grown on glass substrate at 400 °C using zinc chloride as precursor with different molar concentrations varying from 0.05 to 0.2 M. X-ray diffraction patterns reveal that ZnO films are polycrystalline with hexagonal wurtzite structure with preferred orientation in (002) plane. Optical measurements show that transmittance reaches a maximum value of 95% in the visible region for ZnO films prepared from precursor with 0.05 M concentration. The films obtained from the precursor with 0.1 M concentration have the highest electrical conductivity and photocurrent values.     

Dispersive optical constants and electrical properties of nanocrystalline CuInS2 thin films prepared by chemical spray pyrolysis

Nanocrystalline CuInS₂ thin films were deposited on borosilicate glass substrates via chemical spray pyrolysis method. The structural, morphological, optical, and electrical properties were studied as a function of increasing annealing temperature from 250 to 350 ̊C. XRD analysis showed mixed phases at lower temperatures with the preferred orientation shifting towards the (112) chalcopyrite CuInS₂ plane at higher substrate temperature. The crystallite size increased slightly between 13 and 18 nm with increase in annealing temperature. The optical band gap was determined on basis of Tauc extrapolation method and the Wemple–Di-Domenico single oscillator model. Possible structural and quantum confinement effect may have resulted in relatively larger band gaps of 1.67–2.04 eV, relative to the bulk value of 1.5 eV. The presence of Cu_xS in the as-deposited and wurtzite peaks after annealing at 350 ^̊C play a role in influencing the optical and electrical properties of CuInS₂ thin films.     

Functional properties of transparent ZnO thin films synthetized by using spray pyrolysis for environmental and biomedical applications

Spray pyrolysis is a promising method for producing thin, transparent films on glass substrates. ZnO thin films synthesized by this method exhibit high crystallinity, adhesion and chemical resistance. They also possess the ability to degrade water pollutants and exhibit antibacterial properties under UV light. The crystalline structure of these films has been studied using grazing X-ray diffraction (GIXRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM), while transmission electron microscopy (TEM) has been used to investigate their composition and purity. Other techniques such as X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and ultraviolet–visible spectroscopy were also employed. ICP-OES was used to evaluate photocatalyst leaching. These transparent thin films have exceptional optical properties, with a transmittance of 95%. The photocatalytic degradation of 4-Nitrophenol (4-NP) by ZnO thin films showed a degradation rate of 94% in 270 min with a kinetic constant value of 3.1 × 10⁻³ mM/min. The films are also highly durable and reusable, exhibiting superior performance compared to other ZnO photocatalysts. The bactericidal activity of these transparent films was also evaluated, with a value of 60.6% being obtained using Escherichia coli after irradiating the films with UV light for 3 h.     

Effect of gamma irradiation on structural,morphological and optical properties of thermal spray pyrolysis deposited CuO thin film

This study reports the influences of gamma irradiation (GI) in the range of 20–100 kGy on CuO thin films via thermal spray pyrolysis technique on the glass substrates. The results demonstrate significant influences of GI on the crystallographic, microstructural and optical characteristics of CuO thin films. The obtained XRD results showed that the crystallinity of the films deteriorates by gradually decreasing crystallite size (from 59.13 to 46 nm) as applied gamma doses increases. However, the basic monoclinic crystal structure remains same. The dislocation density and lattice strain increased with the rise of GI absorbed dose due to the creation of defects. The values of number of crystallites per unit surface area increased as dose increased indicating the abundance of crystallization of nano CuO thin films. A UV–Vis–NIR spectrophotometer was utilized to determine the optical properties and obtained results indicated that the optical energy band gap (OBG) energies reduced from 2.00 to 1.72 eV as the doses increased from 0 to 100 kGy. No distinctions of the monoclinic phase of virgin CuO thin film have been perceived under applied absorbed doses, notwithstanding the slight deterioration of the crystallinity and narrowing the OBG.     

喷雾热解法制备掺锑氧化锡透明导电膜

以四氯化锡和三氯化锑为原料,采用喷雾热分解的方法在片状日用玻璃基材和石英玻璃基材上制得掺锑氧化锡(ATO)透明导电薄膜。运用XRD和SEM分别对薄膜的结构和形貌进行了表征。研究了锑的掺杂量、成膜温度和沉积时间对薄膜方阻和在可见光范围内的平均透过率的影响。实验结果表明,当三氯化锑的掺杂量为四氯化锡的8%(物质的量分数)、成膜温度为550℃、喷涂时间为12 s时,可使所得薄膜的方阻达最低,为40Ω/□,可见光范围内的平均透过率为70%。     

超声喷雾热分解法制备p型氧化锌多晶薄膜

采用超声喷雾热分解法在玻璃衬底上以醋酸锌水溶液[Zn(CH3COO)2·2H2O]、醋酸铵(CH3COONH4)和硝酸铝[Al(NO3)3·9H2O]的混合溶液为前驱体生成了N-Al共掺P型氧化锌薄膜.考察了前驱体溶液浓度、载气流速、热解温度对实验结果的影响.用XRD和SEM测试手段对薄膜进行了晶体结构和表面形貌的表征,结果表明所制备的薄膜为六角纤锌矿结构的氧化锌薄膜,表面均匀,结构致密,具有强烈的呈c轴垂直于衬底的(002)择优取向.对薄膜进行了电学测试和光致发光性能测试,结果表明制备的薄膜为P型氧化锌薄膜,薄膜的光致发光明显具有氧化锌薄膜的特点.     

Crystallization of amorphous silicon thin films deposited by PECVD on nickel-metalized porous silicon

ABSTRACT: Porous silicon layers were elaborated by electrochemical etching of heavily doped p-type silicon substrates. Metallization of porous silicon was carried out by immersion of substrates in diluted aqueous solution of nickel. Amorphous silicon thin films were deposited by plasma-enhanced chemical vapor deposition on metalized porous layers. Deposited amorphous thin films were crystallized under vacuum at 750 [DEGREE SIGN]C. Obtained results from structural, optical, and electrical characterizations show that thermal annealing of amorphous silicon deposited on Ni-metalized porous silicon leads to an enhancement in the crystalline quality and physical properties of the silicon thin films. The improvement in the quality of the film is due to the crystallization of the amorphous film during annealing. This simple and easy method can be used to produce silicon thin films with high quality suitable for thin film solar cell applications.