Undoped Tin Oxide Research Articles

Characterization and Performance Evaluation of Ni-Doped SnO2 Thin Films for Optoelectronic Applications: Structural, Optical, and Electrical Insights

Abstract Undoped and Ni-doped tin oxide 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 analysis revealed a polycrystalline behavior with a tetragonal structure and a preferential orientation along the 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.

Effect of weak doping with cobalt over the optical magnitudes of tin oxide thin films

This paper aims to investigate the different properties of cobalt-doped and undoped tin oxide thin films. The tin oxide thin films were doped with different atomic percentages of cobalt, ranging from 0% (undoped) to 2% and 4%, using a cost-effective and easily accessible technique known as spray pyrolysis with a moving nozzle at 490 °C. The phase identification of the different thin layers was carried out using X-ray diffraction, which indicated that the compound is homogeneous has a polycrystalline structure and is, with preferential orientation growth at the (211) level. The optical properties of the synthesized thin films were investigated using UV-visible spectroscopy in the range from 300 to 900 nm, which allowed the estimation of both linear and nonlinear optical properties. The results of the investigations into the linear optical properties indicated that the samples have a direct band gap energy between 3.75 to 3.81 eV, permittivity between 2.67 to 3.266, photoelectrons between 0.2 to 3.35 = 1025, and refractive index between 1.778 to 1.875. The results also indicated that the absorption cross section changes with photon energy and the number of photoelectrons, where it has an approximately constant value at low energies. Moreover, the nonlinear optical properties were determined using the Sheik-Bahae model, which revealed that the samples have the same maximum two-photon absorption (TPA) process coefficient of 3.63 cm/W and the same maximum nonlinear refractive index (NRI) value of 6.91 × 10−8 cm2/W.

Silicon solar cell with undoped tin oxide transparent electrode

Silicon solar cell with undoped tin oxide transparent electrode

Surface Dopants‐Induced Interfacial Bonding Greatly Enhances Active Phase‐Support Interaction of Sintering‐Resistant Catalyst for Automotive CO Oxidation

AbstractSupported nanoparticle catalysts are widely used to remove CO pollution in automobile emission control. During vehicle use, catalysts need to experience high‐temperature environments, leading to sintering of active phase and loss of activity. Synthesizing cost‐effective catalysts with simultaneously high catalytic activity and sintering resistance is of great importance but remains challenging. In this study, we show that Cu phase supported on commercial antimony‐doped tin oxide (ATO) is relatively resistant to sintering and can operate at temperatures below 200 °C without any performance degradation after high temperature aging. Specifically, T50 (the temperature of 50 % conversion) of CO conversion over the Cu/ATO sample is maintained at 148 °C before and after high‐temperature aging treatment at 800 °C. The strong active phase‐support interactions could be used to stabilize Cu active phase by taking advantage of extra interfacial bonding stability between Cu islands and surface antimony dopants in ATO, and finally tune activity and stability of the catalysts. The Cu‐on‐ATO ensemble shows excellent resistance against sintering, with conversion efficiency remaining nearly unchanged upon high‐temperature aging at 800 °C for 2 to 10 h. In contrast, strong sintering resistance characteristic of catalysts cannot be attained by supporting Cu on undoped tin oxide (SnO2) or conventional Al2O3 due to absence of specific anchoring sites on the support oxide surfaces. Our findings open up the path in heterogeneous catalysis for the design of active and sintering‐resistant catalysts utilizing surface engineering strategies.

Enhanced electrical and optoelectronic properties of W doped SnO2 thin films

In the present study, undoped tin oxide (SnO2) and tungsten (W) doped tin oxide (1, 2, 3, 4 and 5 wt% of W doping) thin films were deposited by the homemade spray pyrolysis technique and their structural, microstructural, optical, electrical, and optoelectronic properties are described. X-ray diffraction analysis confirmed that all the prepared thin films belonged to a tetragonal crystal structure with a space group of P42/mnm. The elemental oxidation state of Sn4+, O2− and W6+ was confirmed by the X-ray photoelectron spectroscopy (XPS) analysis. The scanning electron microscopy revealed that the surface morphology of SnO2 thin films was slightly modified by W doping. The presence of Sn, O and W and their elemental compositions were confirmed using the energy dispersive X-ray spectroscopy. The 3 wt% of W doped SnO2 (SnO2:W) thin films showed maximum optical transmittance of about 90% in the visible and NIR region. The direct optical bandgap varied between 3.60 eV and 3.84 eV. Photoluminescence spectra showed noticeable enhancement in the UV emission peak at 362 nm and green emission peak at 525 nm of SnO2:W thin films. The high charge carrier concentration of 2.89 × 1020 cm−3 was observed for 3 wt% of W doping. The Hall mobility of the undoped SnO2 thin films was found to be 94 cm2/Vs. A high figure of merit of 8.30 × 10−3 Ω−1 was obtained for the thin films doped with 3 wt% of W.

Performance analysis of aqueous Al-ion electrolyte based dye sensitized solar cell

Photovoltaic performance of the aqueous Al-ion electrolyte-based dye-sensitized solar cells (DSSCs) was investigated by varying the aluminium nitrate concentration, ranging from 0.02 to 0.1 M and using Eosin-Y (EY) sensitized antimony-doped tin oxide (ATO) photoanode with platinum (Pt) as counter electrode. Photoconversion efficiency (PCE) peaks for 0.1 M using the source of 100 mW cm−2 with AM 1.5G (standard) solar simulator under ambient condition, photocurrent density (JSC) reaches 3.76 mA/cm2 and efficiency (PCE, η) 3.17%. Most of the work that exist in literature with (K, Na, Co, Li, etc. based) aqueous electrolyte quoted the maximum efficiency 1.55% whereas, the present work with pure aqueous Al-ion electrolyte gives 50% of higher efficiency over the quoted value. Moreover compared to the undoped tin oxide photoanode, this work with Sb doped tin oxide shows an enhancement of efficiency about 80%.

Green synthesis of tin oxide based nanoparticles using Terminalia bellirica seed extract: impact of operating temperature and antimony dopant on sensitivity for carbon dioxide gas sensing application

ABSTRACT Green synthesis of undoped tin oxide (SnO2) and 2 wt% antimony doped tin oxide (Sb:SnO2) for carbon dioxide (CO2) gas sensing application is reported. The structural, morphological and optical properties of nanoparticles were investigated using XRD, SEM, EDX, HRTEM, FTIR and UV-Vis characterisation techniques. CO2 gas sensing studies were carried out by using calibration setup on pellets of nanoparticles. From XRD, SEM and HRTEM analysis, the average size of Sb:SnO2 nanoparticles were found decreased than the SnO2 nanoparticles. EDX analysis indicated the presence of tin, antimony and oxygen elements in the structure of nanoparticles. The presence of functional groups responsible for the formation of nanoparticles was identified by FTIR spectra. Bandgap of SnO2 and Sb:SnO2 nanoparticles was found to be 3.67 eV and 3.47 eV respectively. The sensitivity of SnO2 and Sb:SnO2 nanoparticles at the optimized operating temperature was found as 18.32% and 35% at 1000 ppm CO2 gas concentration.

Emergence of ferromagnetism through the metal-insulator transition in undoped indium tin oxide films

We present a detailed study of the emergence of bulk ferromagnetism in low-carrier-density samples of undoped indium tin oxide. We use annealing to increase the density of oxygen vacancies and change the sample morphology without introducing impurities through the metal insulator transition (MIT). We utilize a novel and highly sensitive ``Corbino-disk torque magnetometry'' technique to simultaneously measure the thermodynamic and transport effects of magnetism on the same sample after successive annealing. With increased sample granularity, the carrier density increases, the sample becomes more metallic, and ferromagnetism appears as the resistance approaches the MIT. Ferromagnetism is observed through the detection of magnetization hysteresis, the anomalous Hall effect (AHE), and hysteretic magnetoresistance. A sign change of the AHE as the MIT is approached may elucidate the interplay between the impurity band and the conduction band on the weakly insulating side of the MIT.

Al-doped SnO2 thin films: impacts of high temperature annealing on the structural, optical and electrical properties

Undoped Tin Oxide (SnO2) and 4, 8, 14 at.% Aluminum (Al) doped SnO2 thin films (hereafter Sn1-xO2:Alx) were fabricated by thermal vacuum evaporation and stacked layer method, respectively. Following this, a detailed investigation of the impacts of Al doping and annealing temperature on the structural, optical and electrical properties of the synthesized films were carried out. The XRD results show that the films possess tetragonal lattice structures and for both doped and undoped SnO2, the relative intensities of the major diffraction peaks increase with annealing temperature. The high temperature annealing improves the crystallinity and reduces the stacking faults of Sn1-xO2:Alx films. UV–Vis–NIR spectrophotometric studies revealed that Sn1-xO2:Alx films annealed at high temperature have good transmittance which can reach up to 87.84% in the visible region. The optical bandgap gradually decreases with higher annealing conditions and lies within the range of 3.36–3.86 eV. Other properties like penetration depth, Urbach energy, strength of electron–phonon interaction and photoluminescence spectra were also studied. Electrical characterization reveals that Al doping content reduces the carrier mobility and carrier concentration while annealing temperature enhances both of these. This can be attributed to the reduced grain boundary scattering and interatomic bonding at higher annealing temperatures and ionized impurities at higher Al concentration. High annealing suppresses the sheet resistance of all the Sn1-xO2:Alx films and the lowest sheet resistance (268.50 Ω/cm2) is observed at 550 °C annealing for the undoped SnO2 films.

A novel and potentially scalable CVD-based route towards SnO2:Mo thin films as transparent conducting oxides

In this report, we prepared transparent and conducting undoped and molybdenum-doped tin oxide (Mo–SnO2) thin films by aerosol-assisted chemical vapour deposition (AACVD). The relationship between the precursor concentration in the feed and in the resulting films was studied by energy-dispersive X-ray spectroscopy, suggesting that the efficiency of doping is quantitative and that this method could potentially impart exquisite control over dopant levels. All SnO2 films were in tetragonal structure as confirmed by powder X-ray diffraction measurements. X-ray photoelectron spectroscopy characterisation indicated for the first time that Mo ions were in mixed valence states of Mo(VI) and Mo(V) on the surface. Incorporation of Mo6+ resulted in the lowest resistivity of 7.3 times 10^{{ - 3}} Omega ,{text{cm}}, compared to pure SnO2 films with resistivities of 4.3left( 0 right) times 10^{{ - 2}} Omega ,{text{cm}}. Meanwhile, a high transmittance of 83% in the visible light range was also acquired. This work presents a comprehensive investigation into impact of Mo doping on SnO2 films synthesised by AACVD for the first time and establishes the potential for scalable deposition of SnO2:Mo thin films in TCO manufacturing.Graphical abstract

Theoretical modeling of Pd-SnO2 based ethanol gas sensor

In this paper, we fabricate two devices, undoped tin oxide (UTO) and 1 wt% palladium-doped tin oxide (PdTO) thick films for ethanol (C2H5OH) gas sensors. UTO and PdTO samples were deposited on alumina substrate using screen-printing technology. The fabricated UTO and PdTO sample was used as ethanol gas sensor in range (0-5000 ppm) at operating temperature 473 K. The results showed the highest response (∼71%) for varying concentrations of ethanol (5000 ppm) at operating temperature 473 K. Also response/recovery time was observed and it was ∼41 s / 125 s. our experimental data was well supported by the proposed theoretical model.

Realization of highly conducting and transparent SnO2 thin films by optimizing F/Sn molar ratio for electrochemical applications

In the present work, fluorine-doped and undoped tin oxide thin films were deposited on microscopic glass substrate by nebulized spray pyrolysis technique at a constant substrate temperature of 350 °C. The influence of fluorine doping on the physical properties of tin oxide has been investigated by depositing the films by varying the F/Sn precursor molar ratio. The structural, morphological, chemical, optical and electrical properties of the films were characterized by X-ray diffractometer, transmission electron microscope, selected area electron diffraction, field emission scanning electron microscope, X-ray photoelectron spectroscopy, ultraviolet visible near infrared spectroscopy, and Hall effect measurements. The results suggest that deposited films are well adhered and uniformly deposited on the substrate. The structural analysis exhibit that the films are highly polycrystalline, crystallized in tetragonal structure with preferred orientations perpendicular to (200), (211) and (110) planes, and without any secondary phases. Optical transmittance greater than 75% in the visible region is obtained with an optical bandgap energy lying in the range 3.98 – 4.07 eV. Minimum resistivity, for optimized fluorine doped on tin oxide thin films, was in the range of 9.002×10−4 Ω-cm at room temperature. Hall Effect measurements show that the fluorine-doped films are degenerate semiconductors with n-type electrical conductivity. The analysis results show that device quality, highly transparent and stable fluorine doped tin oxide thin films which are having least resistivity values for the minimum doping concentration of 6.1% of fluorine can be prepared by nebulizer spray pyrolysis technique.

Co-sputtered tantalum-doped tin oxide thin films for transparent conducting applications

A transparent conducting material combines high electrical conductivity with high optical transparency. Such materials are actively sought for their applications in optoelectronic devices and consumer electronics. Undoped tin oxide is a wide-bandgap semiconductor that is optically transparent in the visible range but lacks the electrical conductivity necessary for its function as a transparent conductor. In this study, conductive tin oxide thin films were obtained through extrinsic doping with tantalum, which is considered one of the best dopants due to its oxidation state and smaller ionic radius than that of tin. The films were deposited by co-sputtering; radio-frequency sputtering was applied to tin oxide, and then variable-power direct-current sputtering was applied to tantalum to achieve films with tantalum concentrations in the range of 2.6–15.5 at%. The resulting films were highly transparent, with a bandgap in the range of 4.1–4.2 eV and a minimum electrical resistivity of 2.44 × 10−3 Ω cm, corresponding to a Hall mobility of 8.62 cm2/V⋅s. The suitability of these films as transparent conductors was evaluated.

Oxygen vacancy injection-induced resistive switching in combined mobile and static gradient doped tin oxide nanorods.

Resistive switching devices offer a great potential for advanced computing and data storage, including neuromorphic networks and random-access memory. State-of-the-art memristors are mostly realized by a three-layer structure, which is comprised of an active metal oxide layer sandwiched between two metal electrodes. Thus, there is always an interface involving two materials differing strongly in crystallographic and electronic properties. In this study, we present a resistive switching nanorod device based on a metal oxide sandwiched between two transparent conductive oxide electrodes. Thus, the system is characterized by a different, smooth interface offering new possibilities for increased energy efficiency and transparent electronics. Antimony-doped tin oxide (ATO) is used as an electrode material. The heavily doped ATO nanorods, exhibiting a good conductivity, are produced by a templated electrochemical deposition approach of alloy particles with subsequent thermal oxidation. The process enables precise control of the doping level within the nanorods and the formation of a doping level gradient. Electrical characterization reveals that a stronger gradient between heavily doped and undoped tin oxide within the nanorods results in a more rectifying character of the junction. Three-domain nanorods consisting of an undoped tin oxide segment in between two ATO segments are utilized to introduce memristive properties into the nanorod device. The resistive switching of these nanorods can be attributed to an oxygen vacancy doping gradient introduced during thermal oxidation. These vacancies are mobile within the tin oxide host structure and their injection from the ATO segment into the undoped tin oxide segment results in altered conductivity of the device, when an external bias is applied.

Tin oxide gas sensor on tin oxide microheater for high-temperature methane sensing

Despite the ever-increasing demand for methane detectors in residential and industrial locations, a long life semiconductor-based methane sensor is yet elusive. The problem is rooted in the high decomposition temperature of the methane molecule. Here, we disclose a tin oxide gas sensor heated up to its operating temperature using a ten micron-thick undoped tin oxide microheater which can operate at temperatures as high as 850 °C, sufficient for the spontaneous pyrolysis of methane. Operating at temperatures above 700 °C, the device selectively senses methane in atmospheres contaminated with CO and H2. The response and recovery times are both ~10 s, and the CH4 detection limit is 50 ppm, rendering the developed sensor appropriate for online measurement of methane level in hot exhaust gases. Operating continuously at 700 °C in air, the device exhibits no noticeable aging in a test duration of 30 days.

Study the Optical Properties of Undoped and Antimony Doped Tin Oxide Films Prepared by APCVD Technique

In the present study, antimony doped tin oxide (SnO2:Sb) thin films are prepared by atmospheric pressure chemical vapor deposition (APCVD) technique by varying the doping concentration in very small range, 1- 1.4 wt.% at a constant substrate temperature of 480 oC. The effect of Sb-doping concentration on the optical behavior of SnO2 film deposited on glass substrates are analyzed and discussed. Optical measurements showed that the average optical transmittance decreased with increased Sb concentration, and each of absorbance, absorption coefficient and extinction factor were increased in same way and regularly with increasing the concentration of Sb. However the optical reflectance and the refractive index were irregularly increased in same way with increasing the concentration of Sb. A little decrease of energy gap from 3.96 to 4.015 eV with increasing Sb concentration is observed.

Enhanced antimicrobial, antioxidant, in vivo antitumor and in vitro anticancer effects against breast cancer cell line by green synthesized un-doped SnO2 and Co-doped SnO2 nanoparticles from Clerodendrum inerme

A novel approach was employed for the synthesis of un-doped tinoxide and Cobalt-doped tinoxide (Co-doped SnO2) nanoparticles (NAPs) by using aqueous extract of Clerodendrum inerme with the help of eco-friendly superficial solution combustion method. Synthesized NAPs were characterized by different spectroscopic techniques and results from XRD, TEM, SEM, EDX and UV–Vis examines confirmed the successful synthesis, crystalline nature and spherical structure of un-doped SnO2 and Co-doped SnO2 NAPs with the average grain size of 30 and 40 nm; and band gap energy of 3.68 and 2.76 eV respectively. Antimicrobial propensity of the synthesized NAPs was determined by agar well assay, SEM, TEM and confocal laser scanning microscopic analysis against various bacterial and fungal strains. Synthesized Co-doped SnO2 NAPs were unveiled the extraordinary antibacterial and antifungal activities against E. coli, B. subtilis, A. niger, A. flavus, and C. albicans with the zone of inhibitions of 30 ± 0.08 mm and 26 ± 0.06 mm, 17 ± 0.04 mm, 23 ± 0.08 mm and 26 ± 0.06 respectively which were also evidenced from SEM, TEM and confocal laser scanning microscopy. In addition, green synthesized Co-doped SnO2 NAPs were demonstrated the substantial antioxidant activity by scavenging DPPH, significant in vitro anticancer and in vivo antitumor activity on breast carcinoma cells (MCF-7) and Ehrlich ascites tumor cell lines respectively than standard. The hemolytic activity disclosed low cytotoxicity of fabricated NAPs (0.89 ± 0.05%) at 5 mg/mL, which was indicated their biocompatibility potential. Hence, the multi-purpose properties of synthesized NAPs presented in the current study can be further deliberated for pharmaceutical and nanomedicine applications.

Sensing of ammonia gas by undoped and aluminum-doped tin oxide nanoparticles by Raman spectroscopy

The study of gas sensing properties of $$\hbox {SnO}_{2}$$ has been widely carried out mainly using electrical methods where a change in resistance or / and conductance of $$\hbox {SnO}_{2}$$ is measured when it is exposed to the sample. In this work, a spectroscopic approach was employed using Raman intensity as a tool to study the sensing of ammonia by undoped and aluminum-doped $$\hbox {SnO}_{2}$$ nanoparticles. The study showed a variation of intensity of the classical Raman modes of $$\hbox {SnO}_{2}$$ , when $$\hbox {SnO}_{2}$$ was exposed to ammonia. The response to ammonia by nanoparticles of different sizes and doping concentrations was calculated. This study also revealed the optimum crystallite size and doping concentration suitable for sensing ammonia. However, the most important conclusion that could be drawn from this study was that the response of $$\hbox {SnO}_{2}$$ to ammonia could be detected at room temperature through Raman spectroscopy unlike in the case of electrical studies, where a high temperature is required for sensing.

Synthesis and Characterization of Cu-Doped SnO<sub>2</sub> Thin Films by Aerosol Pyrolysis Technique for Gas Sensor Application

Thin films of un-doped and Cu-doped tin oxide were synthesized on quartz substrates by the purpose-built aerosol pyrolysis apparatus from 0.2 M SnCl4.5H2O – ethanol solution. CuCl2.2H2O was used as a source of Cu dopant. The Cu dopant of 1, 3 and 5 wt.% were used for doping SnO2 film. The morphological, structural, optical and electrical properties under the influence of the Cu-doping was examined by FE-SEM, XRD, UV-Vis transmission spectroscopy and Hall effect measurement technique. XRD patterns of all films exhibited rutile-phase SnO2. The doping content of 1%Cu improved the film crystallinity. The Cu doping content decreased optical bandgap from 4.36 eV for undoped SnO2 to 4.28 eV for 3%Cu-doped SnO2. The further Cu doping content increased the bandgap energy to 4.32 eV. The resistivity was increased for doping of Cu 1% but it was decreased with further increasing in Cu-doping contents

Structural, electrical and optical properties of SnOx films deposited by use of atmospheric pressure plasma jet

Structural, electrical and optical properties of undoped tin oxide thin films (SnOx) deposited on silicon and glass slides by use of an atmospheric pressure plasma jet at substrate temperatures varying between 300 °C and 500 °C were determined. One role of the used plasma is the promotion of SnO2 formation and reduction of organic residues from the tetra-n-butyltin (IV) precursor by supplying a highly reactive oxygen-containing atmosphere. Moreover, film properties were compared to SnOx films prepared by a vacuum direct current sputtering procedure. Scanning electron microscopic investigations showed high specific surface area and porous films at 300 °C substrate temperature. With increasing this temperature a decrease in film thickness and roughness of the films could be observed. These experiments were supplemented by transmission electron microscopy and showed the formation of a dense layer close to the substrate with a more porous layer on top of it. Spectral ellipsometry further supported these results and allowed to determine the thickness of the films as well as the thickness of the dense and porous part. X-ray diffraction pattern indicated the presence of a predominantly crystalline film structure (SnO2, cassiterite) at 500 °C substrate temperature with an average grain size of ~4 nm. Comparing to this, film deposited by vacuum sputtering method were more crystalline with average grain sizes of ~12–14 nm. Additionally, the presence of SnO2 on the surface was demonstrated by X-ray photoelectron spectroscopy. Films with an average transmittance of >85% and low resistivities of 7.2 × 10−2 Ωcm even at lower substrate temperatures of 300 °C could be achieved, whereby electrical film properties (conductivity) were superior to those of films prepared by sputter deposition. First attempts to show gas sensing properties were conducted and revealed a response toward ammonia gas atmospheres.