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N-doped titania nano sheets and N-doped titania/tungsten dioxide nano rods were synthesized by two step hydrothermal method. The composition, structural, functional, morphological and optical properties of the as synthesized N-TiO₂/WS₂ hybrids were characterized by XRD, UV-DRS, PL, FE-SEM with EDAX, TEM, FT-IR and Raman spectroscopy. Surface area and thermal stability of the catalysts were analyzed by BET and TG/DTA techniques. The photocatalytic activity of the heterojunction catalyst was evaluated towards the decomposition of a harmful dye namely congo red in an aqueous solution under visible light irradiation. The results show superior photocatalytic activity for N-TiO₂/WS₂ nanocomposite. This unusual photocatalytic activity is attributed to the synergistic effect between WS₂ and N-TiO₂.

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Present work is focused on the improvement of gas sensing and opto-electronic properties of cadmium oxide (CdO) thin films deposited by chemical spray pyrolysis technique, with different cobalt (Co) dopant concentrations in the final spray solution. The XRD patterns reveal that the preferential growth is shifted between (111) and (200) depending on the Co- doping concentrations. The Cd-O bond vibrations were confirmed by micro-Raman analysis. The oxidization state of metal elements was determined by XPS analysis. The FE-SEM analysis revealed the variation in surface microstructure due to the variation in Co- doping concentration in CdO thin films. The elemental composition of deposited films was estimated using EDS. The formaldehyde gas response of 0.50 wt% Co- doped CdO thin film was 23%. The electrical properties were estimated by Hall measurements in van der Pauw configuration. The 0.50 wt% Co- doped CdO thin film showed a maximum carrier mobility of about 87 cm 2 /Vs and a photocurrent of 2.50 nA at 42 V. The Co- doped CdO thin films showed a high optical transmittance of about 84% in the range of 600–1100 nm. The band gap varies between 2.38 eV and 2.50 eV. The estimated high figure of merit is 4.79 × 10 −3 Ω −1 for 0.50 wt% of Co- doped CdO film.

The ruthenium (Ru) doped CdO thin films were deposited by spray pyrolysis method on glass substrate, with various Ru concentrations (0.1, 0.125, 0.150, 0.175 and 0.2 wt%). The effect of Ru doping concentration on the electrical, optical, structural, microstructural and gas sensing properties was studied by Hall measurement, UV–vis–NIR spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, micro-Raman and chemi-resistivity method. The results obtained show that the carrier mobility, visible-NIR transparency, surface morphology and gas response are effectively tuned by varying Ru doping concentration. The 0.1 wt% Ru doped CdO thin film shows relatively high optical band gap (2.32 eV) and maximum transmittance (70%) in the range between 600 and 900 nm. The high electrical properties (mobility 110 cm2/V⋅s and carrier concentration 1.77 × 1020 cm−3) are obtained for 0.150 wt% Ru doped CdO thin film. The high formaldehyde gas sensitivity (35%), fast response and recovery time are observed for 0.150 wt% Ru doped CdO thin film.

Solution based chemical spray pyrolysis technique was employed to deposit lanthanum (La) doped cadmium oxide (CdO) thin films on soda-lime microscope glass slides. X-ray diffraction (XRD) analysis revealed that deposited films are polycrystalline having cubic crystal system. The undoped and 0.25 wt % La doped CdO films show relatively intense (111) plane, which is shifted to (200) plane for doping concentrations greater than 0.50 wt %. The parameters such as lattice constants, crystallite size, micro-strain, dislocation density and texture coefficient are extracted from XRD data. Field emission scanning electron microscopy analysis confirmed the smooth and uniform surface. Energy dispersive spectroscopy analysis was used to estimate the preliminary information on elemental composition. The deposited undoped and La doped films possess optical transmittance ranging 78–82% in the visible and near infrared (NIR) region. The estimated direct optical band gap of undoped and La doped CdO thin films is varied between 2.38 eV and 2.46 eV. Hall measurements confirmed the n-type conductivity in the films. The doping-modulated mobility and carrier concentration are ranging 68 cm2/V s–78 cm2/V s, and 1.0 × 1020 cm−3–4.06 × 1020 cm−3, respectively. Room temperature micro-Raman studies confirmed the metal oxide (Cd O) bond vibrations in deposited films. A high figure of merit (11.45 × 10−3 Ω−1) is obtained from 1.0 wt % La doped CdO film.

Praseodymium (Pr) doped CdO thin films with high transparency and high mobility were deposited, using a homemade spray pyrolysis setup, on micro-slide glass substrates preheated at 300 °C. Polycrystalline nature and Cd-O bond vibration of deposited films were confirmed by X-ray diffraction, micro-Raman and Fourier transform infrared spectroscopy analyses. The oxidation state of Cd2+, O2−, and Pr3+ was confirmed by X-ray photoelectron spectroscopy analysis. The highest average particle size (92 nm-FESEM) and high RMS (13.48 nm-AFM) values are obtained for 0.50 wt% Pr doped CdO thin film. The optical band gap is varied between 2.38 eV and 2.52 eV, depending on the Pr doping concentration. Photoluminescence spectra revealed that Pr doped CdO thin film exhibits strong green emission at 582 nm. High mobility (82 cm2/V s), high charge carrier concentration (2.19×1020 cm−3) and high transmittance (83%) were observed for 0.50 wt% Pr doped CdO film. A high figure of merit (9.79×10−3 Ω−1) was obtained for 0.50 wt% Pr doped CdO thin films. The mechanism behind the above results is discussed in detail in this paper.

Direct electron transfer with redox proteins, in third generation biosensors, is already proved to be favored on electrodes modified with nanoparticles. In this work, different crystallographic and morphologic structures of tungsten oxide (WO3) nanoparticles are modified by hydrothermal synthesis at 180 °C. The electrochemical properties of WO3 nanoparticles deposit on ITO electrodes are investigated and the analytical performance of the nitrite biosensor is presented as proof of concept. Despite the inherent features of each nanostructure, the heterogeneous electron transfer with the WO3 nanoparticles modified electrodes is thoroughly improved and, very importantly, the cytochrome c nitrite reductase (ccNiR) enzyme is able to keep its biological function. When compared with bare commercial ITO electrodes, the exchange rate constant of WO3/ITO electrodes with cytochrome c increased one order of magnitude, while the analytical parameters of the ccNiR/WO3/ITO electrodes response to nitrite (the Michaelis–Menten constant is 47 μM and sensitivity of 2143 mA M −1 cm−2) are comparable to those reported for carbon based electrodes. Therefore, these metal oxide nanoparticles are good alternative materials for electrochemical applications, such as non-mediated biosensors.

MTiO₃ (M = Sr, Ca, Ba and Pb) catalysts were synthesized by polymeric precursor method and characterized by using various instrumental techniques such as X-ray diffraction (XRD), UV-diffuse reflectance spectroscopy (UV-DRS), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). TiO₂ were also synthesized by sol-gel method and used for the optimization of reaction parameters such as catalyst weight, dye concentration and pH in the photocatalytic degradation of reactive dyes such as reactive blue 198 (RB 198), reactive black 5 (RB 5) and reactive yellow 145 (RY 145) under UV irradiation. MTiO₃ (M = Sr, Ca, Ba and Pb) catalysts were evaluated towards the photocatalytic decolourization of RB 198, RB 5 and RY 145 under optimized reaction conditions. Among the different metal titanates, strontium titanate showed the highest decolourization (≈90%) of all the three reactive dyes under UV irradiation at 120 minutes and also found to be active under visible irradiation as it decolourises the dyes in about 450 minutes. The degradation rate of strontium titanate was monitored by TOC analyzer. Kinetic studies of the photocatalytic degradation of reactive dyes confirmed that the reaction followed the pseudo first order kinetics.

In the present work, a spray pyrolysis technique was employed to deposit cerium (Ce) doped cadmium oxide (CdO) thin films with low level doping concentrations (0.25, 0.50, 0.75 and 1.0 wt%). The crystallite size and lattice parameter values were estimated from X-ray diffraction analysis. X-ray diffraction patterns reveal the shift of preferential growth orientation from (111) to (200) planes on incorporating Ce in the CdO matrix. The oxidation state of Ce, Cd and O in the deposited films was determined by X-ray photoelectron spectroscopic (XPS) studies. Surface microstructures of the films were analyzed by atomic force microscopy and their surface nature was studied by field emission scanning electron microscopy (FE-SEM). The electrical properties of the deposited films were determined by Hall measurements in the van der Pauw configuration. The charge carrier concentration of the CdO thin film increased from 1.0 × 1020 cm−3 to 3.85 × 1020 cm−3 on doping 0.50 wt% Ce; whereas, resistivity decreased from 9.32 × 10−4 Ω cm to 3.81 × 10−4 Ω cm. The deposited Ce-doped CdO thin films for various concentrations showed an increase in the average optical transmittance to 85% from that of 72% for the CdO film in the visible and NIR region. The band gap was gradually increased from 2.38 eV to 2.63 eV due to an increase in the Ce doping at various levels. The emission properties of CdO and Ce doped CdO thin films were studied by a photoluminescence spectrum recorded at room temperature. The figure of merit estimated for 0.50 wt% of Ce doped CdO film is 9.18 × 10−3 Ω−1.

Thin films of Zn 1− x Nd x O were deposited by spray pyrolysis on Si(111) substrates preheated at 400 °C temperature and were studied as a function of neodymium (Nd)-doping concentration. X-ray diffraction (XRD) patterns confirmed that the deposited films possess hexagonal wurtzite ZnO structure. Further, it is observed that the doped films show a preferential orientation along the c -axis (0 0 2), which is perpendicular to the substrate. The un-doped films seem to be having a bit low-crystallinity, which is corroborated by the scanning electron microscope (SEM) analysis that showed nano-crystalline like features. Further, SEM analysis showed that the Nd doping triggers the formation bubble-like structure on top of the nano-crystalline structure. The SEM microstructures are interpreted with the Micro-Raman studies. Photoluminescence (PL) and XRD characterizations indicate that above 5 at.% doping concentrations, the Nd atoms preferentially agglomerate in the large islands.

Doped metal oxide semiconductors have received greater attention for the development of gas sensor, working at low temperature, as well as of optoelectronics. In this work, a post transition metal ion of bismuth (Bi) doped cadmium oxide (CdO) thin films were deposited by a cost-effective pyrolytic spray process at substrate temperature of 300 °C. The effects of Bi-doping concentrations on the microstructural, gas sensing and optoelectronic properties of CdO thin films are systematically studied. The CdO film doped with 0.75 wt% of Bi exhibits high response (86.20%) to formaldehyde at a low operating temperature of 130 °C with satisfactory stability, selectivity and anti-interference to humidity. The response mechanism to formaldehyde is discussed in details. Optical results indicate that an improved transmittance above 80% in visible and NIR region was observed for all the Bi-doped CdO thin films with an enhanced optical band gap, in comparison with undoped CdO. Photoluminescence study indicates the presence of optical defects such as neutral donors and deep centers in CdO thin films. The high figure of merit value (4.56 × 10−3 Ω-1) obtained from 0.50 wt% of Bi-doped CdO is superior to the previously reported. The improved carrier mobility (78 cm2/V⋅s) is obtained from 0.25 wt% of Bi-doped CdO thin film. The present investigation indicated that the Bi-doped CdO thin films would be an attractive candidate for formaldehyde gas sensing and optoelectronic applications.

a b s t r a c t This work reports the structural, optical, electrical and thermoelectric properties of vanadium pentoxide (V2O5) thin films deposited at room temperature by thermal evaporation on Corning glass substrates. A post-deposition thermal treatment up to 973 K under atmospheric conditions induces the crystallization of the as-deposited amorphous films with an orthorhombic V2O5 phase with grain sizes around 26 nm. As the annealing temperature rises up to 773 K the electrical conductivity increases. The films exhibit thermoelectric properties with a maximum Seebeck coefficient of −218 V/K and electrical conductivity of 5.5 (� m)−1. All the films show NIR-Vis optical transmittance above 60% and optical band gap of 2.8 eV.

In this work, we report results concerning the performances of thin-film transistors (TFTs) where the channel layer is based on microcrystalline zinc tin oxide (ZTO) processed by spray pyrolysis technique. TFTs made with ~30 nm thick ZTO channel layer deposited at a substrate temperature of 400°C and 300°C exhibited, respectively, a saturation mobility of ~2.9 cm2·V-1·s-1 and 1.45 cm2·V-1·s-1; VON voltage of ~0.15 V, and 0.2 V; a sub-threshold swing of ~400 mV/dec and 500 mV/dec; ON/OFF ratio at the onset of hard saturation current of ~3.5×105 and 6×103, for a drain to source voltage of 10 V (close to or below the gate to source voltage). This indicates that the substrate temperature is relevant in determining the devices' electronic performances.

The effect of substrate temperature (Ts) on the properties of pyrolytically deposited nitrogen (N) doped zinc oxide (ZnO) thin films was investigated. The Ts was varied from 300 °C to 500 °C, with a step of 50 °C. The positive sign of Hall coefficient confirmed the p-type conductivity in the films deposited at 450 °C and 500 °C. X-ray diffraction studies confirmed the ZnO structure with a dominant peak from (1 0 0) crystal plane, irrespective of the variation in Ts. The presence of N in the ZnO structure was evidenced through X-ray photoelectron spectroscopy (XPS) analysis. The obtained high N concentration reveals that the 450 °C is the optimal Ts. Atomic force microscope (AFM) analysis showed that the surface roughness was increased with the increasing Ts until 400 °C but then decreased. It is found that the transmittance of the deposited films is increased with the increasing Ts. The optical band gap calculated from the absorption edge showed that the films deposited with Ts of 300 °C and 350 °C possess higher values than those deposited at higher Ts.

Molybdenum (0.5 at%) doped indium oxide thin films deposited by spray pyrolysis technique wereirradiated by 100 MeV O 7þ ions with different fluences of 5 10 11 ,1 12 and 1 10 13 ions/cm 2 .Intensity of (222) peak of the pristine film was decreased with increase in the ion fluence. Filmsirradiated with the maximum ion fluence of 1 1310 ions/cm 2 showed a fraction of amorphous nature.The surface microstructures on the surface of the film showed that increase in ion fluence decreases thegrain size. Mobility of the pristine molybdenum doped indium oxide films was decreased from 122 to48 cm 2 /V s with increasing ion fluence. Among the irradiated films the film irradiated with the ionfluence of 5 1110 ions/cm 2 showed relatively low resistivity of 6.7 10 4 O cm with the mobility of75 cm 2 /V s. The average transmittance of the as-deposited IMO film is decreased from 89% to 81% dueto irradiation with the fluence of 5 1110 ions/cm 2 .& 2012 Elsevier Ltd. All rights reserved. 1. IntroductionTransparent conducting oxides (TCOs) constitute an unusualclass of materials possessing two physical properties such as highoptical transparency (T) and high electrical conductivity (

N-doped ZnO films were radio frequency (RF) sputtered on glass substrates and studied as a function of oxygen partial pressure (OPP) ranging from 3.0×10 −4 to 9.5×10 −3 Pa. X-ray diffraction patters confirmed the polycrystalline nature of the deposited films. The crystalline structure is influenced by the variation of OPP. Atomic force microscopy analysis confirmed the agglomeration of the neighboring spherical grains with a sharp increase of root mean square (RMS) roughness when the OPP is increased above 1.4×10 −3 Pa. X-ray photoelectron spectroscopy analysis revealed that the incorporation of N content into the film is decreased with the increase of OPP, noticeably N 1s XPS peaks are hardly identified at 9.5×10 −3 Pa. The average visible transmittance (380-700 nm) is increased with the increase of OPP (from ∼17% to 70%), and the optical absorption edge shifts towards the shorter wavelength. The films deposited with low OPP (≤ 3.0×10 −4 Pa) show n-type conductivity and those deposited with high OPP (≥ 9.0×10 −4 Pa) are highly resistive (>10 5 Ω·cm)

Molybdenum doped indium oxide (IO) thin films were deposited on the Coring F1737 glass substrates at 400 °C by spray pyrolysis technique. The Mo doping was varied between 0 and 4 at.%. The films were characterized by their structural, electrical and optical properties. The films are confirmed to be cubic bixbyite In 2 O 3 with a strongest orientation along (222) for 0.5 at.% Mo, which is shifted to (400) plane when the Mo doping is increased to ≥ 1.2 at. %. The films deposited with 0.5 at.% Mo showed high mobility of ~90 cm 2 /Vs, resistivity of ~6.8 x 10 -4 Ω cm and carrier concentration of ~1.01 × 10 20 cm -1 with > ~73% transmittance in the visible range between 500 and 800 nm. The transmittance is well extended into near infrared region.

High visible to near infrared (NIR) transparent Mo (0–1 at%) doped In2O3 (IMO) thin films with high carrier mobility were deposited on Corning-1737 glass substrates at 400 °C by spray pyrolysis experimental technique. The films were annealed in vacuum (∼1×10−4 mbar) at 550 °C for 45 min. XRD analysis confirmed that indium oxide belongs to cubic bixbyite structure. The preferred growth orientation along (2 2 2) plane for low Mo doping level shifts to (4 0 0) for higher Mo doping levels. Crystallite sizes extracted from the XRD data corroborate the changes in full-width at half-maximum due to the variation in Mo doping. Scanning electron microscopy study illustrates the evolution in surface microstructures as a function of Mo doping. The negative sign of Hall coefficient confirmed n-type conductivity. Films with high mobility of ∼149 cm2/(V s), carrier concentration of ∼1.0×1020 cm−3, resistivity of ∼4.0×10−4 Ω cm and high figure of merit of ∼1.02×10−2 Ω−1 were observed for post-annealed films (0.5 at% Mo). The obtained high average transparency of ∼83% in the wavelength range 400–2500 nm confirms that transmittance is well extended into the NIR region.

Copper oxide thin films were obtained by annealing (temperature ranging between 100 and 450 °C) the metallic Cu films deposited on glass substrates by e-beam evaporation. XRD studies confirmed that the cubic Cu phase of the as-deposited films changes into single cubic Cu 2 O phase and single monoclinic CuO phase, depending on the annealing conditions. The crystallite size is varied between ~ 12 and 31 nm. The lattice parameters of cubic Cu and Cu 2 O phases are estimated to ~3.60 and ~4.26 A, respectively. The films with Cu 2 O phase showed p-type characteristics. The conductivity is decreased linearly with the decreasing temperature (1/T), which has confirmed the semiconductor nature of the deposited films. The calculated activation energy is varied between 0.10 and 0.16 eV The surface microstructure is changed depending on the variation in the annealing temperature. The poor transmittance of the asdeposited films (

Indium molybdenum oxide thin films were deposited using different radio-frequency sputtering units on glass substrates at room temperature from an In 2 O 3 (95 wt.%): Mo (5 wt.%) target. The film thickness ranges between 160 and 275 nm. The chamber volume of Unit-1 was ~2.4 times larger than that of Unit-2. Apart from the chamber volume, a significant difference between the two units was the sputtering pressure. The films were characterized by their structural, morphological, optical, and electrical properties. A strong reflection from (222) plane was obtained for the ~275 nm thick films deposited in Unit-1. The films deposited with

Magnesium matrix composites reinforced with SiO2 coated carbon fibers have been investigated, with an emphasis given on the relation between the material strength and interfacial microstructure. The composites were studied as a function of aluminium (Al) content that is varied between 0 and 9 wt%. The obtained results indicate that the reactivity at the C/Mg–Al interface of the composite can be controlled by varying the Al content. The low Al content in C/Mg–1Al has been completely dissolved in the matrix with no segregation even after solidification, leading to the best mechanical performance. If the Al content is increased to ≥3 wt% (composites such as C/AZ31 and C/AZ91), the SiO2 coatings are fully depleted due to an extensive formation of carbides at the interface. The precipitates are further identified as Al2MgC2 phase that is similar to binary carbide Al4C3. SiO2 coating on the fiber layer prior to fabrication of composite is found to be a promising way to suppress the carbide formation and enable the use of Mg–Al matrix with appropriate Al content.

Indium molybdenum oxide (IMO) thin films were deposited by RF magnetron sputtering on glass substrates at room temperature. The deposition and argon partial pressures were maintained at 6.0 × 10−1 Pa and 3.0 × 10−1 Pa, respectively. The oxygen partial pressure (OPP) was varied in the range 1.0–6.0 × 10−3 Pa. The films were sputtered at 40 W for 30 min using the target consisted In2O3 (98 wt%): Mo (2 wt%). The films are polycrystalline with a slight preferential orientation along (2 2 2) plane. The crystallinity is increased with the increasing OPP. The negative sign of Hall coefficient confirmed the n-type conductivity. A maximum mobility ∼19 cm2 V−1 s−1 is obtained for the films deposited with OPP of 3.6 × 10−3 Pa. The average visible transmittance calculated in the wavelength ranging 500–800 nm is ranging between 2% and 77%. The optical band gap calculated from the absorption data is varied between 3.69 and 3.91 eV. A striking feature is that the work function of the films is wide ranging 4.61–4.93 eV. A possibility of using the produced IMO films as transparent conducting oxide in photovoltaic applications such as organic solar cells is discussed in this article.

Transparent and highly conducting gallium zinc oxide (GZO) films were successfully deposited by RF sputtering at room temperature. A lowest resistivity of ∼2.8×10−4 Ω cm was achieved for a film thickness of 1100 nm (sheet resistance ∼2.5 Ω/□), with a Hall mobility of 18 cm2/V s and a carrier concentration of 1.3×1021 cm−3. The films are polycrystalline with a hexagonal structure having a strong crystallographic c-axis orientation. A linear dependence between the mobility and the crystallite size was obtained. The films are highly transparent (between 80% and 90% including the glass substrate) in the visible spectra with a refractive index of about 2, very similar to the value reported for the bulk material. These films were applied to single glass/TCO/pin hydrogenated amorphous silicon solar cells as front layer contact, leading to solar cells with efficiencies of about 9.52%. With the optimized deposition conditions, GZO films were also deposited on polymer (PEN) substrates and the obtained results are discussed.

Thin films of copper oxide were obtained through thermal oxidation (100–450 °C) of evaporated metallic copper (Cu) films on glass substrates. The X-ray diffraction (XRD) studies confirmed the cubic Cu phase of the as-deposited films. The films annealed at 100 °C showed mixed Cu–Cu 2 O phase, whereas those annealed between 200 and 300 °C showed a single cubic Cu 2 O phase. A single monoclinic CuO phase was obtained from the films annealed between 350 and 450 °C. The positive sign of the Hall coefficient confirmed the p-type conductivity in the films with Cu 2 O phase. However, a relatively poor crystallinity of these films limited the p-type characteristics. The films with Cu and CuO phases show n-type conductivity. The surface of the as-deposited is smooth (RMS roughness of 1.47 nm) and comprised of uniformly distributed grains (AFM and SEM analysis). The post-annealing is found to be effective on the distribution of grains and their sizes. The poor transmittance of the as-deposited films (

Transparent wide band gap indium molybdenum oxide (IMO) thin films were rf sputtered on glass substrates at room temperature. The films were studied as a function of sputtering power (ranging 40–180 W) and sputtering time (ranging 2.5–20 min). The film thickness was varied in the range 50–400 nm. The as-deposited films were characterized by their structural (XRD), morphological (AFM), electrical (Hall Effect measurements) and optical (visible-NIR spectroscopy) properties. XRD studies revealed that the films are amorphous for the sputtering power ≤ 100 W and the deposition time ≤ 5 min, and the rest are polycrystalline with a strong reflection from (222) plane showing a preferential orientation. A minimum bulk resistivity of 2.65 × 10 − 3 Ω cm and a maximum carrier concentration of 4.16 × 10 20 cm − 3 are obtained for the crystalline films sputtered at 180 W (10 min). Whereas a maximum mobility (19.5 cm 2 V − 1 s − 1 ) and average visible transmittance (∼ 85%) are obtained for the amorphous films sputtered at 80 W and 100 W respectively for 10 min. A minimum transmittance (∼ 18%) was obtained for the crystalline films sputtered at 180 W (∼ 305 nm thick). The optical band gap was found varying between 3.75 and 3.90 eV for various sputtering parameters. The obtained results are analyzed and corroborated with the structure of the films.

Indium molybdenum oxide thin films were RF sputtered at room temperature on glass substrates with a reference base pressure of 7.5 × 10 − 4 Pa. The electrical and optical properties of the films were studied as a function of oxygen partial pressures (OPP) ranging from 1.5 × 10 − 3 Pa to 3.5 × 10 − 3 Pa. The obtained data show that the bulk resistivity of the films increased by about 4 orders of magnitude (from 7.9 × 10 − 3 to 7.6 × 10 1 Ω-cm) when the OPP increased from 1.5 × 10 − 3 to 3.5 × 10 − 3 Pa, and the carrier concentration decreased by about 4 orders (from 1.77 × 10 20 to 2.31 × 10 16 cm − 3 ). On the other hand, the average visible transmittance of 30.54% of the films (brown colour; OPP = 1.5 × 10 − 3 Pa) was increased with increasing OPP to a maximum of 80.47% (OPP = 3.5 × 10 − 3 Pa). The optical band gap calculated from the absorption edge of the transmittance spectra ranges from 3.77 to 3.88 eV. Further, the optical and electrical properties of the films differ from those deposited at similar conditions but with a base pressure lower than 7.5 × 10 − 4 Pa.

In this work we present a study on the effect of annealing temperatures on the structural, morphological, electrical and optical characteristics of gallium doped zinc oxide (GZO), indium zinc oxide (IZO) and indium-tin-oxide (ITO) films. GZO and IZO films were deposited at room temperature by r.f. magnetron sputtering, whereas the ITO films were commercial ones purchased from Balzers. All films were annealed at temperatures of 250 and 500 °C in open air for 1 h. The GZO and ITO films were polycrystalline. The amorphous structure of as-deposited IZO films becomes crystalline on high temperature annealing (500 °C). The sheet resistivity increased with increase in annealing temperature. GZO films showed an increase of 6 orders of magnitude. The optical transmittance and band gap of as-deposited films varied with annealing. The highest transmittance (over 95 %) and maximum band gap (3.93 eV) have been obtained for ITO films.

Thin films of molybdenum-doped indium oxide (IMO) were prepared by a 3-source, cylindrical radio-frequency magnetron sputtering at room temperature. The films were post-annealed and were characterized by their structural (X-ray diffraction) and optical (UV–VIS–NIR spectrophotometer) properties. The films were studied as a function of oxygen volume percentage (O 2 vol.%) ranging from 3.5 to 17.5. The structural studies revealed that the as-deposited amorphous films become crystalline on annealing. In most cases, the (222) reflection emerged as high intensive peak. The poor visible transmittance of the films as-deposited without oxygen was increased from ∼ 12% to over 80% on introducing oxygen (3.5 O 2 vol.%). For the films annealed in open air, the average visible transmittance in the wavelength ranging 400–800 nm was varied between 77 and 84%. The films annealed at high temperatures (> 300 °C) decreased the transmittance to as low as

Mixed thin films of (CdO) 1− x (PbO) x (0 ≤ x ≤ 1) were deposited from spray pyrolytic decomposition of aqueous solutions of cadmium and lead acetates on glass substrates at a substrate temperature of 350 °C. These films were characterized for their structural (X-ray diffraction (XRD)) and optical (UV-Vis-NIR spectrum) properties as a function of PbO volume percentage ( x ). XRD studies confirm the cubic phase of CdO and orthorhombic phase of α-PbO. The crystallinity of (111) and (200) planes of the cubic phase of CdO is found to increase with increasing PbO vol.% until x = 0.25 and then decreases for x = 0.50 whereas the crystallinity of the (001) ⁎ , (111) ⁎ and (002) ⁎ planes of PbO increases with increasing vol.% of x from 0.25 to 1.00. The mean crystallite size calculated from XRD data is ranging from191 to 671 A. The average transmittance in the visible region (500–850 nm) varies between 40 and 68%. The direct optical band gap value of these films varies from 1.96 to 2.69 eV.

Thin films of fluorine-doped tin oxide (SnO2:F) on glass were prepared by spray pyrolysis technique using stannous chloride (SnCl2) and ammonium fluoride (NH4F) as precursors. The as-prepared films were characterized for their structural and electrical properties and are discussed in detail in this article. The surface morphology studies revealed that the films are grainy and the roughness of undoped films has been reduced on fluorine doping. X-ray diffraction (XRD) studies revealed that the films are polycrystalline. It further revealed that the undoped films grow along the preferred orientation of (211), whereas all the doped films grow along (200). The minimum sheet resistance 1.75 Ω/□ achieved in the present study for the films doped with 15 wt.% F is the lowest among the reported values for these materials prepared using SnCl2 precursor. The electrical transport phenomenon has been analyzed in order to find out the possible scattering mechanism that limiting the mobility of charge carriers.

Thin films of antimony-doped tin oxide (SnO2:Sb) were prepared by spray pyrolysis using stannous chloride (SnCl2) and antimony trichloride (SbCl3) as precursors. The antimony doping was varied from 0 to 4 wt%. Scanning electron microscopy (SEM) revealed the surface morphology to be very smooth, yet grainy in nature. X-ray diffraction (XRD) shows films to have preferred orientation, which varies with the extent of antimony doping: undoped films prefer the (2 1 1) orientation, while the (3 0 1) orientation is preferred for doping levels of 0.5 and 1.0 wt%. For higher doping levels, the (2 0 0) orientation is preferred. This difference in preferred orientations is reflected in the SEM of the films. Atomic force microscopy (AFM) reveals that film roughness is not affected by antimony doping. The minimum sheet resistance (2.17 ohm/square) achieved in the present study is lower than values reported to date in SnO2:Sb films prepared from SnCl2 precursor. The Hall mobility of undoped SnO2 films was found to be 109.52 cm(2)/V s, which reduces to 2.55 cm(2)/ Vs for the films doped with 4 wt% of Sb. On the other hand, the carrier concentration, which is 1.23 x 10(19) cm(-3) in undoped films, increases to 2.89 x 10(21) cm(-3) for the films doped with 4 wt% of Sb. (c) 2004 Elsevier B.V. All rights reserved.

Mixed thin films of (CdO)1−x(PbO)x and (CdS)1−x(PbS)x (x=0.25) were prepared on glass substrates by spray pyrolysis technique for various substrate temperatures 300, 320 and 340 °C. Structural and optical properties were studied. XRD studies reveal the formation of mixed films. The substrate temperature of 340 °C seems to be critical for the formation of CdO–PbO mixed films. It is observed that (CdS)1−x(PbS)x mixed films were formed at all the three substrate temperatures. The direct band gap value of (CdO)1−x(PbO)x and (CdS)1−x(PbS)x mixed films is about 2.6 and 2.37 eV, respectively.

Thin films of antimony doped tin oxide (SnO 2 :Sb) were prepared by spray pyrolysis technique using SnCl 2 as precursorwith the various antimony doping levels ranging from 1 to 4 wt%. The XRD analysis showed that the undoped SnO 2 films growin (211) preferred orientation whereas the Sb doped films grow in (200) plane. Scanning electron microscopy studies indicatedthat the surface of the films prepared with lower doping level (1 wt%) consists of larger grains whereas those prepared withhigher doping levels (.1 wt%) consist of smaller grains. The sheet resistance has been found to be reduced considerably(2.17 V/A) for Sb doped films. To the best of our knowledge this is the lowest sheet resistance obtained for Sb doped SnO 2 thinfilms.q 2004 Elsevier Ltd. All rights reserved. PACS: 60.10. 2 i; 61.16.Bg; 61.82.Fk; 73.61. 2 rKeywords: A. Thin films; A. Semiconductors; A. Tin oxide thin films; C. Scanning electron microscopy 1. IntroductionTin oxide thin films doped with antimony exhibitinteresting electrochemical properties in different electrodeprocesses, such as low temperature electrochemical com-bustion of organic pollutants, ozone production and organicelectro-synthesis [1,2]. Sb doped tin oxide coatings areconventionally prepared by spray pyrolysis of tin tetra-chloride-antimony trichloride mixtures, because of itssimple processing and economic advantages [3–8]. Anti-mony pentachloride has also been tried as a precursor of Sb[9,10]. In the point of view of an inadequate work [11] onthese films using stannous chloride (SnCl

Optical properties of spray deposited antimony (Sb) doped tin oxide (SnO2) thin films, prepared from SnCl2 precursor, have been studied as a function of antimony doping concentration. The doping concentration was varied from 0-4 wt.% of Sb. All the films were deposited on microscope glass slides at the optimized substrate temperature of 400 °C. The films are polycrystalline in nature with tetragonal crystal structure. The doped films are degenerate and n-type conducting. The sheet resistance of tin oxide films was found to decrease from 38.22 Ω/□ for undoped films to 2.17 Ω/□ for antimony doped films. The lowest sheet resistance was achieved for 2 wt.% of Sb doping. To the best of our knowledge, this sheet resistance value is the lowest reported so far, for Sb doped films prepared from SnCl2 precursor. The transmittance and reflectance spectra for the as-deposited films were recorded in the wavelength range of 300 to 2500 nm. The transmittance of the films was observed to increase from 42 % to 55 % (at 800 nm) on initial addition of Sb and then it is decreased for higher level of antimony doping. This paper investigates the variation of optical and electrical properties of the as-deposited films with Sb doping. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Thin-film transistors (TFTs) were fabricated using a 20-nm-thick indium molybdenum oxide (IMO) semiconductor layer at room temperature. The grazing incidence x-ray diffraction patterns confirmed that the deposited films are amorphous. The average transmittance (400-2500 nm) and the optical band gap are ~ 88% and 3.95 eV, respectively. The TFTs fabricated on glass substrates showed a saturation mobility of 4.0 cm2/V·s with an ION/IOFF ratio of 2 × 103 and a threshold voltage of -1.1 V, which are encouraging preliminary results in order to develop IMO as high-performance semiconductor layer.

The optimization of tungsten trioxide (WO3) nanoparticles produced via hydrothermal synthesis for application in electrochromic (EC) devices is reported. The structure and morphology of the nanoparticles are controlled by changing the acidity of the aqueous solvent added to the sol-gel precursor (peroxopolytungstic acid) during synthesis. Orthorhombic hydrated WO3 nanorods or monoclinic WO3 nanoslabs are obtained when HCl is added, while synthesis only in aqueous medium results in a mixture of both types of polymorphs. Dual-phase thin films are processed by inkjet printing deposition of the nanoparticles in flexible polyethylene terephthalate substrate with indium tin oxide coating (ITO PET) followed by the deposition of the precursor solution. When compared with purely amorphous tungsten oxide films, the dual phase ones present higher optical densities and improved capacity, and cyclability stability. The best results, obtained for orthorhombic hydrated nanoparticles (ortho-WO3·0.33H2O), are due to its high surface area and improved conductivity. Additionally, the ex situ X-ray diffraction (XRD) lithiation studies show evidence of a higher distortion of the monoclinic when compared with the orthorhombic crystallographic structure, which contribute to the inferior EC performance. These results validate the use of inkjet printing deposition with low processing temperatures for EC dual-phase thin films containing optimized nanoparticles which are compatible with low-cost substrates.

The high visible–near infrared transparent and high carrier mobility (μ) Mo doped (0.5 at%) indium oxide (IMO) films were deposited by the spray pyrolysis technique. The deposited films were irradiated by 50 MeV Li3+ ions with different fluences of 1 × 1011, 1 × 1012 and 1 × 1013 ions cm−2. X-ray diffraction analysis confirmed the cubic bixbyite structure of indium oxide. A fascinating feature is that the ion irradiation process has introduced a fraction of the molybdenum oxide phase. The μ of as-deposited IMO films is decreased from ∼122.4 to 93.3 cm2 V−1 s−1, following the ion irradiation. The theoretically calculated μ and carrier density values were correlated with those measured experimentally. The transport mechanism has been analysed based on the ionized and neutral impurity scattering centres. The average transmittance (400–2500 nm) of the as-deposited IMO films is decreased from 83% to 60% following irradiation.

Molybdenum (0–1 at. %) doped indium oxide thin films with high near-infrared (NIR) transparency and high carrier mobility were deposited on Corning-1737 glass substrates at 400 °C by a spray pyrolysis experimental technique. X-ray diffraction (XRD) analysis confirmed the cubic bixbyite structure of indium oxide. The preferred growth orientation along the (222) plane for the low Mo doping level (≤0.5 at. %) shifts to (400) for higher Mo doping levels (>0.6 at. %). The crystallite size extracted from the XRD data corroborates the changes in full width at half maximum due to the variation in Mo doping. A scanning electron microscopy study illustrated the evolution in the surface microstructure as a function of Mo doping. The negative sign of the Hall coefficient confirmed the n-type conductivity. A high carrier mobility of ∼122.4 cm2/V s, a carrier concentration of ∼9.5×1019 cm−3, a resistivity of ∼5.3×10−4 Ω cm, and a high figure of merit of ∼4.2×10−2 Ω−1 are observed for the films deposited with 0.5 at. % ...

Molybdenum doped (0–1 at. %) indium oxide thin films with high near infrared (NIR) transparency and carrier mobility were deposited on Corning-1737 glass substrates at 400 °C by spray pyrolysis experimental technique. Films with mobility as high as ∼149 cm2/V s were obtained when annealed in vacuum at 550 °C, which also possess carrier concentration of ∼1×1020 cm−3 and resistivity as low as ∼4.0×10−4 Ω cm. Further, both the average visible transmittance (500–800 nm) and the average NIR transmittance are >83%. This clearly shows that the transmittance is extended well into the NIR region.

Molybdenum doped indium oxide (IMO) thin films rf sputtered at room temperature were studied as a function of oxygen volume percentage (O2 vol. %) varied between 0 and 17.5. The as-deposited films were amorphous irrespective of O2 vol. %. The minimum transmittance (2 vol. %) to a maximum of 90 %. The optical band gap has been increased from 3.80 eV (without oxygen) to 3.92 eV (3.5 O2 vol. %). The films were highly resistive and the hall coefficients were detectable only for the films deposited without oxygen. In order to increase the electrical conductivity, the films were annealed in the range 100-500°C in open-air and N2/H2 gas for 1 hour. The annealed films become polycrystalline with enhanced electrical and optical properties. The effect of annealing conditions on these films will be presented and discussed in detail.

In the present work, the spectroscopic ellipsometry (1.5 - 5.5 eV) was used to investigate the effects of current density induced microstructural variations and their influence on the electronic states of as-prepared and a-Si:H coated porous silicon (PS). The pseudodielectric responses of the low and high current densities (5 and 40 mA/cm2) were analyzed using a multilayer model within the effective medium approximation. The FTIR investigation reveals the enhancement of surface oxide (Si-Ox) layer with current density and the improvement of the Si-Hx band after a-Si:H coating.

Thin films of molybdenum doped indium oxide (IMO) were rf sputtered onto glass substrates at room temperature. The films were studied as a function of oxygen volume percentage (OVP) ranging 1.4 - 10.0 % in the sputtering chamber. The thickness of the films found varying between 180 and 260 nm. The X-ray diffraction pattern showed the films are polycrystalline with the peaks corresponding to (222) and (400) planes and one among them showing as a preferential orientation. It is observed that the preferred orientation changes from (222) plane to (400) as the OVP increases from 1.4 to 10.0 %. The transmittance spectra were found to be in the range of 77 to 89 %. The optical band gap calculated from the absorption coefficient of transmittance spectra was around 3.9 eV. The negative sign of Hall coefficient confirmed the films were n-type conducting. The bulk resistivity increased from 2.26 × 10−3 to 4.08 × 10−1 Ω−cm for the increase in OVP from 1.4 to 4.1 %, and thereafter increased dramatically so as the Hall coefficients were not detectable. From the AFM morphologies it is evaluated that the RMS roughness of the films ranges from 0.9 to 3.2 nm.

Thin films of indium molybdenum oxide (IMO) were rf sputtered onto glass substrates at room temperature. The films were studied as a function of sputtering power (ranging 40 – 180 W) and sputtering time (ranging 2.5 – 20 min). Thickness of the films found varied between 50 – 400 nm. The films were characterized for their structural (XRD), electrical (Hall measurements) and optical (Transmittance spectra) properties. XRD studies revealed that the films are amorphous for the sputtering power ≤ 100 W and deposition time ≤ 5 min. All the other films are polycrystalline and the strongest refection along (222) plane showing a preferential orientation. A minimum bulk resistivity of 2.65 × 10−3 Ω-cm and a maximum carrier concentration of 4.16 × 1020 cm−3 have been obtained for the films sputtered at 180 W (10 min). Whereas maximum mobility (19.5 cm2 V−1 s−1) has been obtained for the films sputtered at 80 W (10 min). A maximum visible transmittance of 90 % (500 nm) has been obtained for the films sputtered at 80 W (10 min) with a minimum of 27 % for those sputtered at 180 W. The optical band gap of the films found varying between 3.75 and 3.90 eV for various sputtering parameters.