Optical Properties Of SnO Research Articles

Structural and optical properties of SnO 2 films grown on α-Al 2O 3(0 0 0 1) by MOCVD

High-quality single crystalline SnO 2 films have been prepared on α-Al 2O 3(0 0 0 1) substrates by the metalorganic chemical vapor deposition (MOCVD) method. Structural and optical properties of the SnO 2 films prepared at different substrate temperatures (500–800 °C) were investigated in detail. The obtained films were pure SnO 2 with the tetragonal rutile structure. The film prepared at 600 °C showed the best single crystalline structure with a single orientation along a-axis. The average transmittance for the SnO 2 films in the visible range was over 90% with a minimum optical gap of 3.58 eV.

The influence of nickel dopant on the microstructure and optical properties of SnO2nano-powders

The microstructure and optical properties of Ni-doped SnO2 nano-powders are studied in detail. By Ni-doping, not only the grain size reduces, but also the grain shape changes from nano-rods to spherical particles. The crystallization becomes better with annealing temperature increasing. The band gap energy decreases as nickel doping level increases. The sp-d hybridization and alloying effect due to amorphous SnO2-x phase should be responsible for the band gap narrowing effect. Nickel dopant does not change the photoluminescence (PL) peak positions.

Optical properties of SnO2−x nanolayers

Specific features in the optical absorption spectra and capacitance-voltage characteristics of SnO2−x nanolayers have been observed. These features are determined by the surface and intergranular states of Sn2+ ions, which appear due to the oxygen deficit and form localized states in the bandgap of SnO2−x. The observed dimensional effect in SnO2−x nanolayers is manifested by an increase in their bandgap width as compared to that in the bulk SnO2.

Electrical, structural and optical properties of SnO 2 thin films prepared by spray pyrolysis

This study investigated the effect of the substrate temperature on the structural, optical, morphological, and electrical properties of undoped SnO 2 films prepared by a spray deposition method. The films were deposited at various substrate temperatures ranging from 300–500 °C in steps of 50 °C and characterized by different optical and structural techniques. X-ray diffraction studies showed that the crystallite size and preferential growth directions of the films were dependent on the substrate temperature. These studies also indicated that the films were amorphous at 300 °C and polycrystalline at the other substrate temperatures used. Infrared and visible spectroscopic studies revealed that a strong vibration band, characteristic of the SnO 2 stretching mode, was present around 630 cm −1 and that the optical transmittance in the visible region varied over the range 75–95% with substrate temperature, respectively. The films deposited at 400 °C exhibited the highest electrical conductivity property.

Investigation of properties of thin oxide films SnO x annealed in various atmospheres

The influence of annealing in various atmospheres on properties of the undoped SnO x thin films has been studied. The films with thickness of ∼400 nm have been deposited on glass substrate by a method of magnetron sputtering in argon–oxygen atmosphere at the pressure inside the chamber 0.9 and 2.7 Pa. The dependences of structural and optical properties of SnO x films from temperature of annealing in air, vacuum and atmosphere hydrogen have been investigated. Correlations between the structural and optical properties of tin oxide films were found.

The Electrical and Optical Properties of SnO2 – Si(n) Structure Solar Cells.

. Abstract: • In this paper the SnO2 will be examined to be used as a transparent antireflection coating with the n –type silicon wafer to fabricate the deposited SnO2 silicon Solar cell using vacuum evaporation technique. This SnO2 layer is simultaneously an antireflecting coating and a transparent upper contact. The oxidation of the Si surface takes place simultaneously with the evaporation process. A semiconductor – insulator – semiconductor (SIS) structure was obtained in such a way. The photoelectrical parameters of such SIS system of AM 1.5 conditions are: the short circuit current 18.5 mA/cm2, the open circuit voltage 0.48 V and the efficiency is 7.0%. The subgap response of the resulted structure is particularly strong and extends to wavelength up to 1100nm

Transparent Conducting Oxide Sculptured Thin Films for Photovoltaic Applications

AbstractOptical losses in thin film solar cells arise due to reflections at the top interfaces where dielectric discontinuities may be significant, e.g., between the glass and transparent conducting oxide (TCO) contact and between the TCO and semiconductor structure. Advanced optical engineering approaches are needed to minimize such losses. One approach is to incorporate multilayered or graded-index TCO films designed to act as broad-band anti-reflectors. Thus, it is important to be able to modulate the near-infrared/visible index of refraction of the TCO over a relatively wide range (e.g., 1.3 < n < 2.0) without increasing its extinction coefficient k or significantly degrading its electrical conductance. Here we report an investigation of SnO2 and ZnO sculptured thin films (STFs) under development for this purpose Sculptured thin films are deposited under low surface mobility conditions using stepwise or continuous variations in the polar and/or azimuthal angles of the deposition flux impinging on the surface. Deposition at a glancing polar angle leads to columnar growth, optical anisotropy, and low ordinary indices of refraction, whereas normal incidence deposition under the same conditions leads to dense isotropic films and high indices. In this study, we explore the dependence of the optical properties of SnO2 and ZnO, including index and birefringence spectra, on the polar deposition angle. Optical modeling reported here assesses the ability of the STF concept to provide tailored TCOs for advanced optical engineering of CdTe solar cell structures.

Electrical and optical properties of SnO2:Sb films prepared on polyimide substrate by r.f. bias sputtering

Antimony-doped tin oxide thin films, with a target composition ranging from 0 to 8wt.% of Sb2O3 content, were deposited on polyimide (PI) substrates by r.f. bias sputtering. Structural, electrical and optical properties of these films were studied by varying the bias voltage. It was found that the best films with a resistivity as low as 1.8×10−3Ωcm and an average transmission above 70% in the visible region can be obtained with a Sb2O3 target content of 6wt.% and substrate temperature of 200°C, and these performances corresponds to the highest crystallinity level.

Influence of the concentration of Sb 2O 3 and the viscosity of the precursor solution on the electrical and optical properties of SnO 2 thin films produced by the Pechini method

SnO 2:Sb multi-layer coatings were prepared by the Pechini method. An investigation was made of the influence of the concentration of Sb 2O 3 and the viscosity of the precursor solution on the electrical and optical properties of SnO 2 thin films. The use of a multi-layer system as an alternative form of increasing the packing and, thus, decreasing porosity proved to be efficient, decreasing the system's resistivity without altering its optical properties.

Influence of heat treatment on the optical properties of SnO2 : Sb thin films deposited by dip coating using aqueous solution

Antimony doped tin oxide thin films were deposited on glass by a chemical route derived from Pechini method. Particular emphasis was given to the microstructure of crystallized films. Crystalline phase formation was studied by grazing incident X-ray diffraction and by thermal analyses. Scanning electron microscopy was carried out for microstructure characterization, surface roughness was observed using scanning tunneling microscope and the optical transmittance measurements were performed in the wavelength range of 200–800 nm.

00/01986 Effects of temperature and r.f. power sputtering on electrical and optical properties of SnO 2

00/01986 Effects of temperature and r.f. power sputtering on electrical and optical properties of SnO 2

Effects of temperature and r.f. power sputtering on electrical and optical properties of SnO 2

Electrical and optical properties of SnO 2, which is a photovoltaic material for solar energy conversion to electricity, have been investigated. Semi-conducting SnO 2 has been grown by r.f. sputtering.We report the influence of process variables, such as substrate temperature and r.f. power. The film resistivity decreases with increasing temperature, but rises with increasing r.f. power: these can be related to crystallite size and the film orientation respectively. From the optical measurements, we deduce a variation of band-gap energy with substrate temperature. We show that the substrate temperature has a subsequent influence on the electrical and optical properties of this material.

Optical properties and electronic transitions of SnO 2 thin films by reflection electron energy loss spectroscopy

Optical properties of SnO 2 thin films in the 4–60 eV energy range are determined by reflection electron energy loss spectroscopy. Bulk and surface electron loss functions, real and imaginary parts of the dielectric function, refraction index, extinction and absorption coefficients are obtained from the analysis of the electron energy loss spectra. Electronic transitions are identified through the interpretation of the optical data. The samples (∼250–500 nm thick) were produced by ion beam-induced chemical vapor deposition. It is found that the compacity of the SnO 2 thin films affects their optical properties and therefore the relative intensity of the observed electronic transitions. The advantages of this method to determine optical properties of thin films are discussed. Inelastic mean free paths (6.2, 17 and 41 Å for electrons traveling in SnO 2 with kinetic energies of 300, 800 and 2000 eV, respectively) are obtained from the corresponding inelastic electron scattering cross-sections.

Structural, electrical and optical properties of SnO 2-x:F-layers deposited by DC-reactive magnetron-sputtering from a metallic target in Ar–O 2/CF 4 mixtures

F-doped SnO x films have been prepared by DC-reactive magnetron sputtering in Ar-O 2/CF 4 mixtures at a deposition temperature of 180°C. The optical and electrical parameters (specific resistance, charge carrier concentration, mobility) were correlated with the chemical composition and the structural properties (phases, grain size). Small concentrations of F increase both the charge carrier concentration and the mobility. Higher fluorine incorporation into the films does not improve the electrical properties, which is attributed to the formation of tin fluorides. The maximum fluorine concentration in the SnO 2−x:F-films, measured by RBS, is 7×10 21 cm −3 (corresponding to 8 at.%). Comparison of the charge carrier concentrations with the fluorine content shows that the electrical activation of the fluorine is smaller than 3.4%. The low electrical activation of the fluorine is tentatively explained by the formation of tin fluorides, leading to low charge carrier concentrations (N D≈1.4× 10 20cm −3). This limits the specific resistivities to values >7×10 −3 Ωcm.

Optical properties of SnO 2 thin films grown by atmospheric pressure chemical vapour deposition oxiding SnCl 4

Tin oxide thin films were grown by chemical vapour deposition (CVD) on glass substrates at atmospheric pressure (AP) and temperatures varying between 350 and 520 °C. A vertical home-made reactor was used for the deposition from SnCl 4 vapours with ambient air as oxidizer. Optical transmission measurements of these films were taken in the spectral range 200–2000 nm, and were analysed with the aid of the physical model introduced by Forouhi and Bloomer describing the optical dispersion in amorphous dielectrics ( A. Foroubi and I. Bloomer, Phys. Rev. B, 34 (1986) 7018 ). It was found that the model describes well the optical properties of APCVD SnO 2 thin films. The structure and the composition of the films changed with the deposition temperature and these changes implied modifications in the optical and electrical properties. Hence, the increase in the deposition temperature was found to imply an increase in the energy distance between bonding and antibonding states and a decrease in the energy band gap, as defined by the physical model. Energy states were found to appear within the energy gap as the deposition temperature increased. These states were related to the enhanced film conductivities.

SnO2:F Thin Films with High Fluorine Contents Produced by Spray Pyrolysis at Constant Substrate Temperature

AbstractFluorine doped tin oxide thin films were prepared from solutions with high fluorine contents using the spray pyrolysis technique; the resulting films were studied by electron and X-ray diffraction methods; the resonant nuclear reaction (RNR) method was used to determine the final concentration of fluorine atoms in our films for different doping levels. Also, electrical and optical properties of SnO2:F films were measured and correlated with deposition and structural parameters obtained from X-Ray diffraction and electron microscopy studies.

Electrical and optical properties of pyrolytically sprayed SnO 2 film—Dependence on substrate temperature and substrate-nozzle distance

The dependence of electrical and optical properties of SnO 2 films, prepared using the spray pyrolysis technique, on the substrate temperature and substrate-nozzle distance was studied. A 0.05 cm diameter spray nozzle was employed ( 1 4 JAU, Spraying Systems Inc., U.S.A.). Films of about 10 −3 Ω cm resistivity and high visible transparency of about 90% were obtained at a substrate temperature of 400°C and a substrate-nozzle distance of 30 cm. It has been observed that substrate-nozzle distance plays an important role in the reaction kinetics of SnO 2 films. At a substrate-nozzle distance greater than 30 cm, the homogeneous reaction enhances and hence impedes the growth rate, resulting in inferior electrical and optical properties of the films.

Studies of electrical and optical properties of SnO 2:P films

The preparation and properties of phosphorus-doped SnO 2 films, deposited on a heated borosilicate glass using the chemical vapour deposition, are reported in this paper. It is observed that the resistivity of the film decreases and its carrier concentration increases as the doping concentration of phosphorus increases up to 3.7 wt.%. The lowest resistivity of the film for 3.7 wt.% of phosphorus is at the optimum temperature of 400°C. The mobility increases with the phosphorus doping up to a doping concentration of 3.7 wt.% P, attaining a maximum value of 30×10 −4m 2V −1s −1, and thereafter it falls off with further doping concentration. The Seebeck coefficient variation with the temperature for different carrier concentrations confirms the degenerate nature of the film. The maximum transmission and the figure of merit in the wavelength region 500–800 nm are found to be 83% and 17 × 10 −3 Ω −1 respectively. The optical band gap of the film is found to be 3.68 eV. The X-ray diffraction pattern for 3.7 wt.% P in solution shows peaks at (110), (101), (200) and (211). At higher doping concentration of phosphorus, the film undergoes a crystalline-to-amorphous transition.

Electrical and optical properties of chemically deposited SnO 2:I coatings

Thin coatings of SnO 2 and SnO 2:I are prepared using the spray pyrolysis technique. The effect of iodine doping on the electrical and optical properties of SnO 2 are studied and compared with other types of doping. The electrical sheet resistance is minimum (30 Ω/□) and optical transmission at solar maximum is 95% for an SnO 2 coating doped with 0.3 wt% iodine. The absorption coefficient data versus photon energy for SnO 2 coatings doped with 0.3 wt% iodine are analyzed and interpreted in terms of direct and indirect allowed transitions.

Effect of hydrogen annealing on electrical and optical properties of SnO 2 thin films

SnO 2 and fluorine-doped SnO 2 films grown by spray pyrolysis were annealed in hydrogen atmosphere at different temperatures in the range 200–450°C for 30 min. Sheet resistance ( R s ) and optical transmission studies were made on these films at room temperature. The R s in undoped SnO 2 was found to decrease with increasing annealing temperature, whereas R s was increasing with the annealing temperature in F-doped films. However, optical transmission is found to decrease in both cases with increasing annealing temperature though the decrease is faster in F-doped films.