Study of structural/microstructural and optical characteristics of tin oxide (SnO2) thin film grown at different substrate temperatures of 325 °𝐂𝐂, 375 °𝐂𝐂, 425 °𝐂𝐂 by spray pyrolysis method

Tin oxide (SnO) thin films is one of the most extremely studied oxides because of its usefulness in UV-detector. SnO is known for wide bandgap of 3.6eV which makes it a good candidate for window layers in heterjunction solar cells. Transition metal chalcogenides (TMCs) exhibits unique properties such as high conversion efficiency, good absorption coefficient and good bandgap energy which make their thin films versatile as a coating materials. Spray pyrolysis have been used to deposit SnO (core), SnO/ZnS, SnO/CrS, SnO/CoS and SnO/CuS (biphasic) at 0.1M concentration and different substrate temperatures of 100oC, 150oC and 200oC. The effect of varying substrate temperatures on the optical and structural properties of the SnO (core) and SnO/TMCs (biphasic) films were examined and analysed. The result showed that the optical transmittance decreased with increase in substrate temperature for SnO (core). The result showed that the absorbance of the SnO thin films at various substrate temperatures vary from 0.10 – 0.7. For the biphasic films, SnO/ZnS, SnO/CrS, SnO/CoS and SnO/CuS the absorbance decreases in the neighbourhood of 300nm-350nm, increases from 350nm-600nm and decreases between 600-100nm for the different substrate temperature of 100oC, 150oC and 200oC. The reflectance spectra of SnO films were found fluctuating between maxima and minima while biphasic films altered the reflectance which showed very low reflectance as observed. The bandgap energy for SnO are 2.00eV, 2.10eV, and 2.20eV at 100oC, 150oC and 200oC substrate temperature. The energy band gap increased with substrate temperature. Whereas for biphasic films, the bandgap was in the neighourhood of 1.10eV1.60eV for the different substrate temperature. The extinction coefficient (k) of SnO films increased with increase in substrate temperature while in biphasic films, the extinction coefficient showed significant reduction in magnitude irrespective of the substrate temperature. The refractive index of all the film samples were generally low irrespective of the substrate temperature. The films:SnO and biphasic displayed low value of dielectric constant irrespective of the substrate temperature. The result equally reveals that the optical conductivity for SnO decreases with increase in the substrate temperature.

Transparent conducting oxides (TCOs) like Indium tin oxide (ITO) have wide attention from all scientists which have low resistance and high visible light transmittance, used as transparent electrodes in many optoelectronic devices such as liquid crystal displays, touch screens, light emitting diodes, and solar cells. In this research, the relationship between the crystallization, optical transmittance, and surface roughness of nanostructured ITO thin films and the change in annealing temperature was investigated. To enhance the efficiency of this material in optoelectronic applications, both the optical transmittance in the visible region and the crystallite size must be increased. These results can be obtained by the heat treatment of the films. Nanostructured ITO thin layer films have been successfully prepared at a substrate temperature equal to (350)℃ by chemical spray pyrolysis (CSP) technique. The physical characterizations of nanostructured ITO thin layer films were investigated at different annealing temperatures (400,450 and 500)℃. The presence of diffraction peaks indicates that the as-deposited and post annealed films are polycrystalline cubic structure and the peak (400) is a preferred growth orientation. For all samples the value of intensity of diffraction peaks increases with increasing substrate temperature. The crystallite size of nanostructured ITO thin films is strongly related to the annealing temperature. The crystallite size estimated from XRD was found to rise with rising annealing temperature. The surface roughness of nanostructured ITO thin layer films increases with rising annealing temperature. High values of transmittance have been measured in the visible region 550 nm equal to (70, 82, 84 and 88)% corresponding to annealing temperature (350,400,450 and 500)℃ respectively.

Fluorine doped tin oxide (FTO) thin films with adequate properties to be used as transparent electrical contact for PV solar cells were synthesised using the spray pyrolysis technique, which provides a low cost operation. The deposition temperature and the fluorine doping have been optimized for achieving a minimum resistivity and maximum optical transmittance. No post-deposition annealing treatments were carried out. The X-ray diffraction study showed that all the FTO films were polycrystalline with a tetragonal crystal structure and preferentially oriented along the (200) direction. The grain size ameliorates with the increase in substrate temperature. The samples deposited with the substrate temperature at 440 °C and fluorine content of 20 wt % exhibited the lowest electrical resistivity (1.8 × 10−4 Ω cm), as measured by four-point probe. Room-temperature Hall measurements revealed that the 20 wt% films are degenerate and exhibit n-type electrical conductivity with carrier concentration of ~4.6 × 1020 cm−3, sheet resistance of 6.6 Ω/□ and a mobility of ~25 cm2 V−1 s−1. In addition, the optimized growth conditions resulted in thin films (~500 nm thickness) with average visible transmittance of 89 % and optical band-gap of 3.90 eV. The electrical and optical characteristics of the deposited films revealed their excellent quality as a TCO material.

Photocatalytic performance and solar cell simulations of TiO2–SnO2:F mixed oxide thin films grown by spray pyrolysis method

Tin oxide films doped with fluorine or antimony are transparent conductors used in optoelectronic devices and solar cells. Silicon oxide thin films are used as diffusion barriers, passivation layers and dielectric layers in the microelectronics industry. Tin oxide thin films are commonly deposited in atmospheric pressure chemical vapor deposition (APCVD) processes by hydrolyzing SnCl[sub 4] or by reacting tetramethyltin with oxygen. The APCVD of silicon oxide films normally involves the reaction of ozone or oxygen with SiH[sub 4] or tetraethylorthosilicate. Gordon et al. recently reported the use of main-group amido complexes and ammonia as precursors in the APCVD of main-group nitride thin films. Because the amido precursors are volatile, easily synthesized, and relatively safe to handle, the authors decided to examine their use as precursors to main-group oxide thin films. This paper reports the successful APCVD of tin and silicon oxide from homoleptic dimethylamido complexes, M(NMe[sub 2])[sub 4] (M = Sn, Si), and oxygen at deposition temperatures ranging from 250 to 400[degrees]C. 14 refs., 2 figs., 1 tab.

Properties of spray deposited tin oxide thin films derived from tri- n-butyltin acetate

This article is about tin oxide (SnO2:Sb:F) thin films prepared (7 samples at each experiment step) successfully on the glass substrate by using spray pyrolysis method. Different solution molarities and different substrate temperatures were used to prepare precursor solution and fabricate thin films, respectively. And then these thin film’s structural, optical and morphological properties were compared. XRD patterns displayed that the deposited films were polycrystalline with tetragonal structure irrespective of molarity and substrate temperature. Each film has a transmittance of more than 60% in visible region. Optical band gap values were found to be in the range of 3.74-3.95 eV. The SEM and AFM images demonstrated that nanocrystalline particles covered all film surfaces. The best optimum property was found at thin films (0.15 M) prepared with at 520 ˚C and the grains are larger for thin films at 520 C when compared with 480 C. Finally, it is understood that when substrate temperature and molarity increased, more regular structure was obtained.

Structural, optical and electrical properties studies of ultrasonically deposited tin oxide (SnO2) thin films with different substrate temperatures

Niobium-doped indium tin oxide (ITO:Nb) thin films are fabricated on glass substrates by radio frequency (RF) magnetron sputtering at different temperatures. Structural, electrical and optical properties of the films are investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), ultraviolet-visible (UV-VIS) spectroscopy and electrical measurements. XRD patterns show that the preferential orientation of polycrystalline structure changes from (400) to (222) crystal plane, and the crystallite size increases with the increase of substrate temperature. AFM analyses reveal that the film is very smooth at low temperature. The root mean square (RMS) roughness and the average roughness are 2.16 nm and 1.64 nm, respectively. The obtained lowest resistivity of the films is 1.2×10−4Ω·cm, and the resistivity decreases with the increase of substrate temperature. The highest Hall mobility and carrier concentration are 16.5 cm2/V·s and 1.88×1021cm−3, respectively. Band gap energy of the films depends on substrate temperature, which is varied from 3.49 eV to 3.63 eV.

Investigations on temperature dependent properties of spray deposited tin oxide thin films

Optimized substrate temperature range for improved physical properties in spray pyrolysis deposited Tin Selenide thin films

Detection of hydrogen sulfide gas is important due to the environmental considerations and the health hazards it posses. Sul-fides are known to be toxic for as a low as 100 ppm/air and hence sensors capable of detecting offensive sulfides are needed for the optimization of auto ventilation system of toilet or kitchen, dentistry etc. The present work talks about the different means of improving the sensitivity and selectivity of the tin oxide thin film towards hydrogen sulfide. The tin oxide thin film is modified with an overlayer of copper oxide nano-film deposited by the mono-layer protected copper nanoclusters and the newly developed liquid-liquid interface reaction technique (LLIRT). The other method involves incorporation of copper in the tin oxide matrix using spray pyrolysis. Modification of the thin film tin oxide surface by copper oxide nanofilm results in the enhancement of the sensitivity (s=100) and selectivity towards H/sub 2/S as compared to the pure tin oxide (s=12) thin film. The effect of thickness of the overlayer copper oxide film on the gas sensing properties is correlated. The surface functionalisation with monolayer protected clusters (MPC's) leads to the room temperature detection of H/sub 2/S. The sensing surface is made by first depositing a thin film of tin oxide on to a glass substrate followed by surface functionalisation with monolayer protected copper nanoclusters capped with different capping agents prepared as per the Brust synthesis route. These nanoclusters enhance the sensitivity of the sensor towards hydrogen sulfide. The environment of copper clusters changes after the exposure to H/sub 2/S gas, allowing the access of copper to gas molecules. This further facilitates the electron transfer between cluster to cluster and hence enhances the conductance of the sensor element. The sensitivity of copper clusters capped with different functional groups and with different chain length is established. The sensitivity of the film is calculated as the ratio of change in the conductance to the original conductance. The effect of surface coverage, morphology, oxidation-state and the amount of copper on the sensitivity have been studied. The correlation between copper incorporation and the improvement in the selectivity and sensitivity towards hydrogen sulfide is discussed.

Undoped and Ni-doped tin oxide (SnO2) thin films were synthesized using the spray pyrolysis technique on ordinary glass substrates. The study aimed to investigate the physico-chemical properties of these thin films using various characterization techniques. X-ray diffraction (XRD) analysis revealed a polycrystalline behavior with a tetragonal structure and a preferential orientation along the [110] direction for both undoped and Ni-doped SnO2 films. Raman spectroscopy confirm the tetragonal rutile structure and shows a slight enhancement of crystallinity for 4% Ni doped SnO2 thin films. Optical measurements showed a decrease in transmittance with increasing dopant ratio, indicating reduced transparency, and a decrease in band gap with Ni insertion. Electrical measurements, conducted through I-V curve analysis, confirmed Ohm’s law compliance and indicated a decrease in resistivity with Ni doping, suggesting improved electrical conductivity. Additionally, the study explored the performance of thin-film solar cells utilizing SnO2 as a transparent conducting layer through numerical simulations using SCAPS-1D software. The effects of Ni doping on the solar cell performance were examined, suggesting potential enhancements or modifications in efficiency and functionality. Overall, the findings provide valuable insights into the structural, optical, and electrical properties of undoped and Ni-doped SnO2 thin films, offering promising avenues for their application in optoelectronic devices.

Optimization of substrate temperature and characterization of tin oxide based transparent conducting thin films for application in dye-sensitized solar cells

Highly conductive and transparent indium tin oxide (ITO) thin films, each with a thickness of 100 nm, were deposited on glass and Si(100) by direct current (DC) magnetron sputtering under an argon (Ar) atmosphere using an ITO target composed of 95% indium oxide and 5% tin oxide for photon-STM use. X-ray diffraction, STM observations, resistivity and transmission measurements were carried out to study the formation of the films at substrate temperatures between 40 and 400 °C and the effects of thermal annealing in air between 200 and 400 °C for between1 and 5 h. The film properties were highly dependent on deposition conditions and on post-deposition film treatment. The films deposited under an Ar atmosphere pressure of ∼1.7×10-3 Torr by DC power sputtering (100 W) at substrate temperatures between 40 and 400 °C exhibited resistivities in the range 3.0–5.7×10-5 Ω m and transmissions in the range 71–79%. After deposition and annealing in air at 300 °C for 1 h, the films showed resistivities in the range 2.9–4.0×10-5 Ω m and transmissions in the range 78–81%. Resistivity and transmission measurements showed that in order to improve conductive and transparent properties, 2 h annealing in air at 300 °C was necessary. X-ray diffraction data supported the experimental measurements of resistivity and transmission on the studies of annealing time. The surface roughness and film uniformity improve with increasing substrate temperature. STM observations found the ITO films deposited at a substrate temperature of 325 °C, and up to 400 °C, had domains with crystalline structures. After deposition and annealing in air at 300 °C for 1 h the films still exhibited similar domains. However, after deposition at substrate temperatures from 40 °C to 300 °C, and annealing in air at 300 °C for 1 h, the films were shown to be amorphous. More importantly, the STM studies found that the ITO film surfaces were most likely to break after deposition at a substrate temperature of 325 °C and annealing in air at 300 °C for 2 or 3 h. Such findings give some inspiration to us in interpreting the effects of annealing on the improvement of conductive and transparent properties and on the transition of phases. In addition, correlations between the conductive/transparent properties and the phase transition, the annealing time and the phase transition, and the conductive/transparent properties and the annealing time have been investigated.