Electrical Properties Of SnO2 Research Articles

Structural, optical, electrical properties and FTIR studies of fluorine doped SnO2 films deposited by spray pyrolysis

Thin films of SnO2:F were prepared by ultrasonic spray pyrolysis method. The effect of fluorine concentration on the structural, optical, and electrical properties of SnO2:F films was investigated. The X-ray diffraction results showed the preferred growth along (110). FTIR was employed to study the defects in SnO2 lattice. The evidence of oxygen vacancy and substitution of fluorine for oxygen in FTIR were investigated. It was found that at low doping levels, fluorine ions preferred to replace the oxygen in the lattice. While beyond a certain doping level, fluorine ions started to occupy interstitial site, which had a negative effect on carrier concentration that, in turn, affected the infrared reflectivity of SnO2:F films. The increased disorder of SnO2 at high doping levels was also shown by FTIR. The discussion of carrier scattering suggested that ionized impurity and/or neutral impurity scattering were the dominant scattering mechanisms in SnO2:F films.

Optical and electrical properties of SnO 2:Sb thin films deposited by oblique angle deposition

The antimony doped tin oxide (SnO 2:Sb) (ATO) thin films were prepared by oblique angle electron beam evaporation technique. X-ray diffraction, field emission scanning electron microscopy, UV–vis–NIR spectrophotometer and four-point probe resistor were employed to characterize the structure, morphology, optical and electrical properties. The results show that oblique angle deposition ATO thin films with tilted columns structure are anisotropic. The in-plane birefringence of optical anisotropy is up to 0.035 at α = 70°, which means that it is suitable as wave plate and polarizer. The electrical anisotropy of sheet resistance shows that the sheet resistance parallel to the deposition plane is larger than that perpendicular to the deposition plane and it can be changed from 900 Ω/□ to 3500 Ω/□ for deposition angle from 40° to 85°, which means that the sheet resistance can be effectively tuned by changing the deposition angle. Additionally, the sandwich structure of SiO 2 buffer layer plus normal ATO films and oblique angle deposition ATO films can reduce the resistance, which can balance the optical and electrical anisotropy. It is suggested that oblique angle deposition ATO thin films can be used as transparent conductive thin films in solar cell, anti-foggy windows and multifunctional carrier in liquid crystal display.

Exploring the microstructural and electrical properties of SnO 2 nanorods prepared by a widely applicable route

Tin dioxide (SnO 2) is a unique functional material with significant technological applications. A good understanding of the microstructure and electronic properties of this material is of fundamental importance in the development of nanodevices. In this paper, SnO 2 nanorods were prepared in bulk quantity by a widely applicable route based on reaction processes. Microstructural investigations by X-ray diffraction and transmission electron microscopy indicated that these nanorods have the tetragonal rutile form of SnO 2, and are structurally perfect and uniform, with widths of 10–25 nm, and lengths of several hundred nanometers to a few micrometers. Electrical measurements by connecting a single SnO 2 nanorod in field-effect transistor configuration showed that these nanorods exhibit good electrical properties. The findings indicate that other one-dimensional nanostructural materials may be manipulated by using this simple technique. This work might provide insight into new opportunities for applications as building blocks for nanoelectronics and active sensing materials.

Effect of fluorine doping on highly transparent conductive spray deposited nanocrystalline tin oxide thin films

The undoped and fluorine doped thin films are synthesized by using cost-effective spray pyrolysis technique. The dependence of optical, structural and electrical properties of SnO 2 films, on the concentration of fluorine is reported. Optical absorption, X-ray diffraction, scanning electron microscope (SEM) and Hall effect studies have been performed on SnO 2:F (FTO) films coated on glass substrates. The film thickness varies from 800 to 1572 nm. X-ray diffraction pattern reveals the presence of cassiterite structure with (2 0 0) preferential orientation for FTO films. The crystallite size varies from 35 to 66 nm. SEM and AFM study reveals the surface of FTO to be made of nanocrystalline particles. The electrical study reveals that the films are degenerate and exhibit n-type electrical conductivity. The 20 wt% F doped film has a minimum resistivity of 3.8 × 10 −4 Ω cm, carrier density of 24.9 × 10 20 cm −3 and mobility of 6.59 cm 2 V −1 s −1. The sprayed FTO film having minimum resistance of 3.42 Ω/cm 2, highest figure of merit of 6.18 × 10 −2 Ω −1 at 550 nm and 96% IR reflectivity suggest, these films are useful as conducting layers in electrochromic and photovoltaic devices and also as the passive counter electrode.

Electrical properties of SnO2 based varistor ceramics with CuO addition

Current–voltage characteristics, temperature dependences of the low-field dc conductivity and the relative dielectric permittivity of tin dioxide based SnO2–Co3O4–Nb2O5–Cr2O3 ceramics with CuO addition in the range 0–8 mol% are studied. These materials exhibit non-Ohmic conduction (the varistor effect). If 0.5 mol% CuO is added, the nonlinearity coefficient is increased from 54 to 75 and the electric field at fixed current density is decreased from 628 to 390 kV m−1. Higher amounts of CuO substantially diminish non-Ohmic behaviour. Thickness dependence of the nonlinearity coefficient and the electric field at fixed current density in SnO2 varistor ceramics is observed. Electrical properties are discussed in the frames of grain-boundary controlled conduction mechanism.

Bulk-quantity synthesis and electrical properties of SnO 2 nanowires prepared by pulsed delivery

Tin dioxide nanowires have been realized via pulsed laser deposition techniques based on a sintered cassiterite SnO 2 target, being deposited on Si (1 0 0) substrates at room temperature. X-ray diffraction indicated that the nanowires show the tetragonal rutile structure in the form of SnO 2. Transmission electron microscopy revealed that the nanowires are structurally perfect and uniform, and diameters range from 10 nm to 30 nm, and lengths of several hundreds nanometers to a few micrometers. Selected area electron diffraction and high-resolution transmission electron microscopy verified that the nanowires grow along the [1 1 0] growth direction. Electric properties were investigated by connecting a single SnO 2 nanowire in field-effect transistor configuration. The SnO 2 nanowires based on field-effect transistor devices exhibited that the SnO 2 nanowires prepared by our method hold better electrical properties.

Carbon nanotube-incorporated direct-patternable SnO 2 thin films formed by photochemical metal-organic deposition

The electrical property of SnO 2 thin film was improved by the incorporation of multi-wall carbon nanotubes (MWNTs). MWNTs were incorporated into SnO 2 photosensitive precursor solution and the direct-patternable film was prepared by photochemical metal-organic deposition. The incorporation of MWNTs into SnO 2 films slightly reduced the transmittance of SnO 2 films due to light scattering by the incorporated MWNTs. In addition, with incorporation of MWNTs, the crystallinity of the SnO 2 hybrid films decreased slightly and the film sheet resistance improved due to enhancement of charge mobility because of the π-bonding nature of MWNTs. Direct-patterning of SnO 2 hybrid films containing MWNTs was performed without photoresist or dry etching. These results suggest that a micro-patterned system can be simply fabricated at a low cost and the electrical properties of SnO 2 films can be improved by incorporating MWNTs.

The morphological, optical and electrical properties of SnO2:F thin films prepared by spray pyrolysis

AbstractCombining the spray pyrolysis and the sol–gel techniques gives the possibility to produce Fluorine doped Tin oxide (SnO2:F) thin films. Transparent conducting SnO2:F thin films have been deposited on glass substrates by the spray pyrolysis technique. This technique for the fabrication of SnO2:F filmsby combining sol–gel process and the spray pyrolysis technique ispresented in this paper. The Sol–gel precursors have been successfully prepared using SnCl2·5H2O and (Ac)F3. The structural, electrical, and optical properties of these films were investigated. The high resolution transmission electron microscopy (HRTEM) and selected area diffraction (SAD) patterns of SnO2:F films show that the gel films lead to a tetragonal structure. The X‐ray diffraction pattern of the films deposited at substrate temperature 530° , the orientation of the films was predominantly [110]. In addition, the surface chemical components were also examined by X‐ray photoelectron spectroscopy (XPS) showing the SnO2:F deposited with the atomic concentration ratios Sn/F 1.82:1. The minimum sheet resistance was 50 Ω and average transmission in the visible wavelength range of 300 to 800 nm was 87.25%. Copyright © 2008 John Wiley & Sons, Ltd.

Preparation and characterization of F doped SnO2 films and electrochromic properties of FTO/NiO films

Abstract The dependence of structural and electrical properties of SnO 2 films, prepared using spray pyrolysis technique, on the concentration of fluorine is reported. X-ray diffraction, FTIR and scanning electron microscope (SEM) studies have been performed on SnO 2 :F (FTO) films coated on glass substrates. Measured values of Hall coefficient and resistivity are reported. The 7.5 m% of F doped film had a resistivity of 15 × 10 −4 Ω cm, carrier density of 18.7 × 10 19 cm −3 and mobility of 21.86 cm 2 V −1 S −1 . The NiO film was coated on an FTO substrate and its electrochromic (EC) behavior was studied and the results are reported and discussed in this paper.

Electrical characterization of SnO2:Sb ultrathin films obtained by controlled thickness deposition

A representative study is reported on the electrical properties of SnO2:Sb ultrathin films (thickness of 40–70 nm) produced by a deposition method based on aqueous colloidal suspensions of 3–5 nm crystalline oxides. The results revealed the films’ electrical behavior in a range of 10–300 K, showing a strong dependence on dopant incorporation, with minimum resistivity values in 10 mol % of Sb content. All the samples displayed semiconductor behavior, but the transport mechanism showed a strong dependence on thickness, making it difficult to fit it to well-known models. In thicker films, the mechanism proved to be an intermediary system, with thermally activated and hopping features. Electron hopping was estimated in the range of 0.4–1.9 nm, i.e., in the same order as the particle size.

Effect of ambient oxygen pressure on structural, optical and electrical properties of SnO 2 thin films

Polycrystalline SnO 2 thin films were deposited on sapphire substrates at 450°C under different ambient oxygen pressures by pulsed laser deposition technique. The effect of ambient oxygen pressure on the structural, optical and electrical properties of SnO 2 thin films was studied. X-ray diffraction and Hall measurements show that increasing the ambient oxygen pressure can improve crystallization of the films and decrease resistivity of the films. A violet emission peak centered at 409 nm was observed from photoluminescence measurements for SnO 2 films under deposition ambient oxygen pressure above 5 Pa, which is related to the improvement of crystalline of the films.

Use of Impedance Spectroscopy in the Study of the Effect of Cr Concentration on the Electrical Properties of SnO<sub>2</sub>-Based Ceramics

This paper reports a study of influence of Cr concentration on the electrical properties and microstructure of SnO2-based powders doped with Mn and Nb, prepared by an organic route (Pechini method). All the samples were compacted into discs and sintered at 1300°C for 3h, resulting in ceramics with relative density varying between 78% and 98%. The powders were characterized by X-ray diffraction analysis. Impedance spectroscopy characterization indicated that the conductivity decreases as Cr concentration increases, probably due to Cr segregation at grain boundaries, which reduces grain size, increasing the number of resistive boundaries.

Effects of Ta2O5 on the electrical properties of SnO2·CuO ceramics

The varistor system SnO2·CuO· Ta2O5 with different Ta2O5 dopants sintered at 1300°C for 80 min was investigated. It is found that Ta2O5 significantly affects the grain size and the electrical properties. The average grain size decreases from 6.8 to 1.9 µm with an increase in Ta2O5 concentration from 0.05 to 1.00 mol%. The sample with 0.05 mol% Ta2O5 has the best nonlinear electrical property and the highest nonlinear coefficient (α = 37.9) and the sample with 0.50 mol% Ta2O5 possesses the highest densification (98.7% of the theoretical density) among all the samples. The reason for the nonlinearity of SnO2 ceramics is explained.

Effect of the fluorine content on the structural and electrical properties of SnO 2 and ZnO–SnO 2 thin films prepared by spray pyrolysis

Transparent conducting oxide thin films of SnO 2 (TO) and of ZnO–SnO 2 binary–binary system (ZO–TO system) have been prepared by the spray pyrolysis method. In this work, we study the influence of fluorine doping concentration on the structural, optical and electrical properties of films above mentioned. Fluorine doped tin oxide (FTO) thin films on glass present resistivity around to 4×10 −4 Ω cm, high optical transmission close to 80% and optical band gap close to 4.5 eV. X-ray diffraction measurements show that the FTO films are highly oriented along the (200) plane parallel to the substrate. ZO–TO films deposited at substrate temperature of 450 °C using alcoholic solutions of ZnCl 2/SnCl 4 with a Zn/Sn=0.40 atomic ratio, presented polycrystalline structures with a mixture of zinc oxide and tin oxide phases (ZO–TO system). These films present a resistivity close to 6 Ω cm and an optical transmission in the visible range of 82%. Further addition of NH 4F to the starting solution lowered the resistivity of ZO–TO thin films to 2.43×10 −1 Ω cm as a consequence of fluorine incorporation. From electrical and optical measurements, the Moss–Burstein effect was found in both TO and ZO–TO thin films.

Formation of large pores and their effect on electrical properties of SnO 2 gas sensors

The effect of large pores on electrical properties of SnO 2 gas sensors has been investigated. Large intergranular pores of 10–20 μm diameter were created in SnO 2 gas sensors by adding starch powder in concentrations from 0 to 15 wt.%. Addition of starch powder did not change sintering behavior and resultant microstructure except for the formation of large pores. Gas sensitivity increased with starch addition. This result was attributed to enhanced diffusion of gases into the bulk SnO 2 through the created large pores. Introduction of large pores in a bulk SnO 2 matrix by adding starch can be a simple and useful way of microstructure control and sensitivity enhancement.

Structural, optical and electrical properties of SnO2:Sb:Tb3+/porous silicon devices

SnO2:Sb sol–gel derived thin films doped with Tb3+ were deposited on porous silicon (PS) layers. Transmission electron microscopy observations, electron diffraction patterns and energy dispersive x-ray analysis revealed the crystallization of small crystallites of cassiterite embedded in the porous layer and the presence of Tb3+ ions in the SnO2 crystallites. The photoluminescence spectrum shows that Tb3+ ions emit highly after annealing at 500 °C. Preliminary characterizations of the electrical and transient electroluminescence of the resulting nanocomposite structures are presented. We discuss the I–V of SnO2:Tb3+/PS device under both forward and reverse bias conditions.

Electrical Properties of SnO<sub>2</sub> and SnAcAc Based Gas Sensors – DC and AC Measurements

Electrical Properties of SnO<sub>2</sub> and SnAcAc Based Gas Sensors – DC and AC Measurements

Mechanism of sensing CO in nitrogen by nanocrystalline SnO2 and SnO2(Pd) studied by Mössbauer spectroscopy and conductance measurements

The mechanism of CO/N2 sensitivity of undoped and Pd-doped nanocrystalline tin dioxide was studied in situ by coupled electrical measurements and 119Sn Mossbauer spectroscopy. Nanocrystalline SnO2 with a grain size of about 6–8 nm was synthesized by the sol–gel method. SnO2(Pd) ([Pd] = 1 at%) was prepared from SnO2 by the impregnation method. Electrical properties of SnO2 and SnO2(Pd) in the presence of CO/N2 were studied at a fixed temperature in the range 50 ≤ T ≤ 380 °C. Addition of Pd strongly increases the sensor response to CO over the whole temperature range. It was shown by Mossbauer spectroscopy that two different mechanisms of gas sensitivity can exist in the presence of CO/N2. The first “low temperature” mechanism (T < 100 °C) may be attributed to redox reactions between surface oxygen and CO catalyzed by PdOx clusters. The second “high temperature” one (125–380 °C) involves oxygen vacancies diffusing into the bulk of the tin dioxide grains which leads to reversible reduction of Sn(IV) to Sn(II).

Effect of Fe2O3 doping on the electrical properties of a SnO2 based varistor

The effect of Fe2O3 addition on the densification and electrical properties of the (0.9895 − x) SnO2 + 0.01CoO + 0.005Nb2O5 + xFe2O3 system, where x = 0.005 or 0.01, was considered in this study. The samples were sintered at 1300°C for 2 h. Microstructure analysis by scanning electron microscopy showed that the effect of Fe2O3 addition is to decrease the SnO2 grain size. J × E curves indicated that the system exhibit a varistor behavior and the effect of Fe2O3 is to increase both, the non-linear coefficient (α) and the breakdown voltage (Er). Considering the Schottky thermionic emission model the potential height and width were estimated. Small amount addition of Fe2O3 to the basic system increases both the potential barrier height and width.

Evaporated thin films of insulating poly-(tetrabromo- p-phenylenediselenide)

It has been shown that thin insulating film at the interface transparent conductive oxide/organic electroluminescent film could improve the performance of organic electroluminescent diodes (OLED). Such insulating film can be inorganic or organic. Poly-(tetrabromo- p-phenylenediselenide) (PBrPDSe) has been proved to be an efficient insulating film in OLED. The properties of these evaporated PBrPDSe thin films have been systematically studied by IR absorption, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, electron spin resonance and optical transmission measurements. It is shown that, when the deposition temperature is kept below the decomposition temperature of the polymer, tetrabromo- p-phenylenediselenide molecule is preserved during the deposition process. However the polymer, which is insoluble in powder form, becomes soluble after deposition. It can be concluded that films are mainly composed of oligomers of tetrabromo- p-phenylenediselenide. The electrical properties of SnO 2/PBrPDSe/Al thin films structures have been studied. The current–voltage characteristics exhibit a rectifying behaviour with a forward direction corresponding to a positive bias of the transparent conductive oxide film, the SnO 2.