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We report herein the analysis of the properties of copper(I) oxide thin films deposited by an optimized ammonium-free successive ion layer adsorption and reaction (SILAR) technique. The Cu2O thin film deposition process was carried out at room temperature using copper acetate monohydrate, sodium citrate as complexing agent, and hydrogen peroxide as precursors of copper and oxygen ions, respectively. The harmless and easy-to-handle sodium citrate replaces the volatile NH4OH commonly employed as complexing agent in the SILAR technique for the deposition of metal oxide thin films. The optical, structural, morphological, and electrical properties of the as-deposited Cu2O thin films were studied as a function of the number of cycles during deposition, as well as their modifications produced by the effect of rapid thermal annealing (RTA) in vacuum in a temperature range of 200–250°C for 1 min, 3 min, and 5 min. The as-deposited thin films had cubic crystalline structure corresponding to the Cu2O phase as determined by x-ray diffraction (XRD), with a direct energy bandgap of 2.43–2.51 eV depending on the number of cycles, and electrical resistivity of the order of 103 Ω cm. The XRD and x-ray photoelectron spectroscopy (XPS) analysis of the Cu2O thin films treated by RTA demonstrated an increase of the crystal size with time and temperature of the RTA and reduction effects from Cu2+ to Cu1+ oxidation states. On the other hand, the RTA treatments also decreased their energy bandgap to 2.38 eV and electrical resistivity to 102 Ω cm. The high energy bandgap values of the Cu2O thin films were attributed to quantum confinement effects produced by their small crystal size in the range of 3.6–8.6 nm. [ABSTRACT FROM AUTHOR]

A set of cadmium sulfide (CdS) thin films was grown on glass substrates by the chemical bath deposition technique at different bath temperatures (Tb). A microwave oven was used to heat the precursor aqueous solution employed to prepare the films in the 60–97 °C interval. The average crystallite size of the CdS films lies in the 7–20 nm range, calculated from X-ray diffraction data. The diffraction patterns reveal that the crystalline structure of CdS nanoparticles is cubic zinc blende (ZB) for 60 ≤ Tb ≤ 93 °C, hexagonal wurtzite (WZ) for 95 ≤ Tb ≤ 97 °C, and ZB-WZ mix of phases for the critical temperature Tb ≅ 94 °C (Tbc). The mixture of both phases is supported by Transmission Electron Microscopy. The CdS films show preferred orientation along (111) and (002) directions for ZB and WZ, respectively. The optical properties reveal significant changes at Tbc, namely, the energy band gap, photoluminescence emission, and refractive index. The photoluminescence results show an additional band at the critical phase transition temperature due to the presence of a high-density Cd interstitial/vacancies, produced by the mix of phases. Furthermore, high-energy transitions above the conduction band also exhibit splitting due to the phase transition. [ABSTRACT FROM AUTHOR]

Cu2O thin films with tailored electrical properties were produced by 25 s plasma reduction of CuO films and immediate oxidation under oxygen flows of 0, 3, 6, 9, 12, 15, and 18 sccm. CuO target films were easily prepared by the dip-coating method and annealing at 400 °C. CuO was transformed to Cu2O by employing an argon plasma treatment devised in our laboratory. Cu2O was produced as the only crystalline phase detected, and the films exhibited smooth surfaces with roughness around 5 nm. All films presented high reflectance in the fundamental absorption region (30%) and high transmittance in the transparency region of Cu2O (65%). The good optical behavior permitted the accurate calculation of optical constants by fitting reflectance and transmittance to an optical model designed with the help of Film Wizard™ software. Variations with oxygen injection were detected for the components of the dielectric function, index of refraction, and absorption coefficient. More importantly, the electrical properties of Cu2O showed a clear dependence on O2 injection. Even though resistivity was on average 80 Ω∙cm, hole mobility varied in the span of 0.75–3.2 cm2/V s, and hole density in the range of 1016–1017/cm3. Upon storage in open-air conditions, the mobility of Cu2O films was increased to 3.8 cm2/V s. The Cu2O films produced show similar quality to those obtained by a sputtering deposition method. However, simpler equipment was employed. The plasma method studied is promising for fast mass production of Cu2O thin films. [ABSTRACT FROM AUTHOR]

Amorphous CeO2 thin films were deposited by a dip-coating method on Corning glass substrates and annealed for one hour at the temperatures (T) of 250, 450, and 550°C in air for crystallization. The precursor solution was prepared by dissolving cerium acetate in methanol, lactic acid, glycerol, and trimethylamine at 55°C. X-ray diffraction (XRD) patterns showed the cubic structure of CeO2. From XRD data and employing the Scherrer formula, the crystallite size (CS) was calculated to be within the 4.0±0.5 to 10±1 nm interval. SEM micrographs revealed cracks of the films annealed at 250 and 450°C, even though for 550°C, the film shows a homogeneous morphology free of cracks. CS increases (from 4.0 to 10 nm) and thickness decreases (from 217 to 182 nm) when T increases. The UV-vis spectra exhibited an average transmittance of 80% in the 300 to 2000 nm wavelength range. Also, from XRD, it was observed that the lattice shrinks and from transmittance that the bandgap energy increases with T. The Raman spectra exhibit 461 cm-1 assigned to F2g mode of the fluorite cubic structure, where F2g hardens when T increases as an effect of the shrinkage of the lattice. [ABSTRACT FROM AUTHOR]

Thin films of the semiconductor alloy Cux(CdTe)yOz system were grown by reactive rf cosputtering. The effects of incorporating both copper and oxygen into a CdTe matrix were investigated. The films were polycrystalline, however, for the highest oxygen concentrations used in this work the grain size was reduced to nanometric dimensions. It is shown in this work that the optical and charge transport properties of the polycrystalline and amorphous films may be tailored by controlling the relative chemical composition. Remarkably, unusual p-type resistivity and mobility values have been measured for the amorphous films. [ABSTRACT FROM AUTHOR]

A regio-regular poly(3-hexylthiophene) (RRP3HT) thin film transistor having a split gate architecture has been fabricated on a doped silicon/silicon nitride substrate and characterized. This device demonstrates AND logic functionality. The device functionality was controlled by applying either 0 or -10 V to each of the gate electrodes. When -10 V was simultaneously applied to both gates, the device was conductive (on), while any other combination of gate voltages rendered the device resistive (off). The p-type carrier charge mobility was about 5×10-4 cm2/V s. The low mobility is attributed to the sharp contours of the RRP3HT film due to substrate nonplanarity. A significant advantage of this architecture is that AND logic devices with multiple inputs can be fabricated using a single RRP3HT channel with multiple gates. [ABSTRACT FROM AUTHOR]

Cd-Sn system thin films were deposited by the spray pyrolysis technique to obtain Cd2SnO4. The solution consisted of tin chloride and cadmium acetate, as sources of Cd and Sn, which were dissolved in a water/isopropanol (4:1) mixture, maintaining an atomic ratio Cd/Sn = 6. The substrate temperature Ts was varied in the 410-500 °C range. XRD patterns showed Cd2SnO4 + SnO2 crystals, decreasing the contribution of SnO2 at lower Ts’s. The films (~ 160 nm) were subjected to post-deposition treatments of rapid thermal annealing (RTA) at 600 °C during 25 s, under two different atmospheres argon and vacuum. The effect of RTA treatments on the properties of this type Cd2SnO4 films has not been formerly reported. In this work, an important improvement in the crystalline quality of the films was obtained after this treatment, showing mainly the Cd2SnO4 phase. Best structural, optical and electrical properties were obtained for films treated in argon. These films showed a preferential orientation along the (222) plane of the Cd2SnO4 with a crystallite size of 35 nm, transmittance higher than 75% (400 ≤ λ ≤ 1500 nm), a resistivity of 2.6 × 10−3 Ω cm and a direct band gap of 3.51 eV. [ABSTRACT FROM AUTHOR]

Cu 2 O thin films were obtained from CuO films at drying temperatures lower than 290 °C and times shorter than 10 min in open atmosphere. A rapid transformation of CuO films to Cu 2 O films at 260 °C evidenced the existence of a useful reduction mechanism that was studied. A metal precursor solution was prepared from the mixing of copper acetate and monoethanolamine in isopropanol. Thin films of 5 layers were deposited by the dip-coating method at a withdrawal speed of 6 cm/min. Each layer was dried in a furnace at 230, 260, 275 or 290 °C for 5, 7 or 10 min. X-ray diffraction, reflectance and transmittance in the UV–Vis region and, specular reflectance in the infrared showed that CuO films are obtained at 230 °C. However, Cu 2 O with good crystallinity and transparency is produced with drying at 260 °C and above, for 10 min and less. Band gaps for CuO and Cu 2 O films were 1.28 eV and 2.18 eV, respectively. FTIR, resistivity and SEM studies evidenced a reduction mechanism that transforms CuO to Cu 2 O. The effect is caused by monoethanolamine decomposition into several other reducing compounds, mainly copper carboxylates. Even though some authors have reported similar precursor solutions with monoethanolamine, none have obtained Cu 2 O in open atmosphere, nor have they explained the organic reaction pathways involved. With the help of other reducing organic compounds, the phenomena can be exploited to produce Cu 2 O films from CuO ones at milder processing conditions, thus enabling applications for flexible electronics. [ABSTRACT FROM AUTHOR]

PbS nanocrystals co-doped simultaneously in Er 3+ and Bi 3+ solutions were grown and the modification of morphological, structural and some optical properties was investigated. The thicknesses of the undoped and doped PbS films were in the ∼560–400 nm range. The morphological changes of the nanocrystals were analyzed using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) techniques. Fourier transform infrared spectroscopy ((FT-IR)) spectra showed a broad absorption band located at ∼3500 cm −1 attributed to stretching of the –OH groups and a sharp band at ∼1384 cm -1 owing to stretching vibrations mode of C O 3 2 - ions. X-ray diffraction displayed a cubic phase in all films and grain size (GS) of the undoped and doped samples were ∼33 and ∼21–17 nm, respectively. The films showed stress, a typical behavior of doped nanocrystals displaying residual strain. The absorbance spectra of PbS film exhibited four absorption bands located at ∼251 nm (∼4.9 eV), ∼610 nm (∼2.0 eV), ∼668 nm (∼1.8 eV) and ∼830 nm (∼1.4 eV) due to strong confinement effect and ∼446 nm (∼2.7 eV), ∼478 nm (∼2.5 eV) corresponding to 4 F 7/2 → 4 I 5/2 , 4 F 3/2 → 4 I 15/2 ( f → f ) transitions of Er 3+ ions. Sharp bands were found at ∼287 nm (∼4.3 eV) and 366 nm (∼3.38 eV), corresponding to transitions of Bi 3+ ions. The band gap energy of films showed a shift in the ∼0.9–1.2 eV range. Raman spectra showed two bands located at ∼450 cm −1 due to the first overtone of the longitudinal optical (LO) phonon (2LO) and a band observed at ∼200 cm −1 which was attributed to the LO (Γ) phonon. A kinetic mechanism using the free energy changes Gibbs is proposed. [ABSTRACT FROM AUTHOR]

CdS, CdS-CdCO 3 and CdCO 3 thin films grown by chemical bath at ∼80, ∼60 and ∼40 °C temperature range were prepared. Morphology and size showed changes as a variety of truncated cube-shaped structures, wires and circles. Energy band gap was ∼2.4 eV (CdS) and ∼4.0 eV (CdCO 3 ), respectively. XRD showed wurtzite crystalline phase for CdS films and a rhombohedral phase for CdCO 3 . Raman spectra in CdS exhibited a peak for A 1 (TO) phonon corresponding to wurzite and CdCO 3 film showed internal vibrations of C O 3 2 − group: v 1 -symmetric stretching (∼1090 cm −1 ) v 3 -asymmetric C O stretching (∼1401 cm −1 ); v 4 -in-plane band of the C O 3 2 − ions and two bands assigned to translations and release of the C O 3 2 − group relative to the Cd atoms: v 13 (∼274 cm −1 ), v 14 (∼169 cm −1 ). Lattice modes v 13 (∼274 cm −1 ), v 3 - asymmetric C O stretching (∼1401 cm −1 ), v 1 -symmetric C O stretching ∼1090 cm −1 were also noted. Finally, a simple thermodynamic analysis is presented to understand the formation of the compounds by calculations of Gibbs free energy and data associated with the corresponding ions of the CdS and CdCO 3 materials in our working conditions. [ABSTRACT FROM AUTHOR]

Cu-O system thin films of 500 nm thickness were deposited on glass substrates by the spray-pyrolysis technique. The substrate temperatures (T) were in the 270-380 °C range with steps of 20 °C, including T = 340 °C. The precursor solution was obtained starting from copper nitrate (Cu(NO)), glucose (CHO) as reducing agent, and a deionized water-2 propanol mixture as solvent. XRD patterns revealed polycrystalline films with different phases depending on the T: (i) CuO + Cu for 270 °C ≤ T ≤ 310 °C, (ii) CuO for 330 °C ≤ T ≤ 340 °C and (iii) CuO + CuO for 360 °C ≤ T≤380 °C. A crystallite size of 21 nm was obtained for cuprite phase (CuO). CuO films exhibited p type conductivity, electrical resistivity of 10 Ω-cm, electrical mobility 4.6 cm Vs and major carrier concentration of 7.2 × 10 cm. A maximum optical transmittance of 75% was obtained in the 650-800 nm range, with an abrupt absorption edge around 520 nm corresponding to the optical gap of 2.37 eV, which was calculated assuming the model for forbidden direct transition (n = 2/3). Uniform deposits and spherical aggregates of the order of 80 nm were observed using Field Emission Scanning Electronic Microscope. [ABSTRACT FROM AUTHOR]

CdO+CdTiO 3 multicomponent oxide thin films were obtained by mixing the CdO and TiO 2 sol-gel precursor solutions, keeping Ti/Cd = 0.65. TiO 2 solution water content was varied from 0 to 5 mol (X) for each Ti mol in steps of 1 mol to evaluate its effect on the properties of the CdO+CdTiO 3 films. The films were obtained by the dip coating method under controlled temperature and relative humidity conditions. Superficial morphology images by optical and scanning electron microscopy revealed a strong effect of the water content on the CdO and CdTiO 3 crystalline grains distribution, showing three different zones. This result was remarked from X-ray diffraction, EDS measurements, UV-Vis, and Raman spectroscopy. In addition, the photocatalytic activity of CdO+CdTiO 3 films was evaluated from the methylene blue in water photobleaching. For the first time, a notable effect of the distribution and content of CdO and CdTiO 3 crystalline grains on the photocatalytic activity of the films is reported. The best photocatalytic activity (k = 0.66 h−1) is obtained for the films deposited with X = 4 mol, corresponding to those with crystalline grains distribution most homogeneous. Also, for these films, the highest Cd excess content to Ti is found (30%), so the highest photocatalytic activity is explained by the higher amount of CdO and CdTiO 3 crystalline grains coupled. [Display omitted] • Crystalline grains distribution and content effect in CdO+CdTiO 3 films on PA activity. • MB maximum degradation corresponds with the CdO and CdTiO 3 highest grains coupling. • CdO, CdTiO 3, and both oxides zones determined from Raman spectroscopy, EDS, and SEM. • Effect water content in solution & nearest zone at surface´s film during its coating [ABSTRACT FROM AUTHOR]

CdSe thin films were prepared by chemical bath and doped in situ with Er 3+ ions. Three impurity levels were prepared by changing the relative volume of the salt solution containing Er 3+ ions in the CdSe growing solution. Changes in the grain size (∼5.5–3.5 nm) and band gap energy (∼1.80–2.25 eV) were observed in the undoped and doped CdSe films, respectively. Photoluminescence studies displayed room temperature emission exhibiting NIR-to visible upconversion. The transition bands 4 I 13/2 → 4 I 15/2 , 2 I 9/2 → 4 I 15/2 and 2 F 9/2 → 4 F 15/2 in the ∼700–850 nm region were investigated. Upconversion emissions were observed from the CdSeEr sample under light excitation (325 nm). The upconversion emission intensity ratio of these transitions is attributed to the variation of the local structure around Er 3+ ions. These results confirm that visible upconversion emissions of Er 3+ in the CdSeEr nanocrystals are mainly produced via two-photon excited-state absorption and energy transfer upconversion processes. [ABSTRACT FROM AUTHOR]

Doping of PbS nanocrystals with Fe 2+ ions leads to changes in properties that make them useful in technology of thin films devices. In this paper we present the growth of PbS doped systematically with the solution containing the Fe 2+ ions (V [Fe2+] ) using the green chemical bath approach, with the goal of studying the effects of such Fe 2+ -doping on the morphological, structural, electrical and some optical properties of the PbS thin films obtained. The morphological changes of the films were followed by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). X-ray diffraction showed growth of all films in the zinc blende phase. The grain size was found to be ∼29 and ∼21–17 nm, for the undoped and doped sample, respectively. The absorbance showed in doped films a weak shoulder located at ∼625 nm (1.98 eV), and this exciton peak was attributed to a 1 S e → 1 S h transition. A shift for the band gap energy was observed by optical absorption from ∼1.56 eV for the undoped sample to ∼2.20–2.25 eV range for the doped films. The resistivity increased from ∼26.13–295.7 (Ω cm), and with respect to the electrical conductivity, mobility decreased from ∼8.8 × 10 −4 –2.1 × 10 −7 (Ω cm) −1 , ∼720.1–2.1 cm 2 V −1 s −1 and carrier from ∼1.9 × 10 15 –4.2 × 10 12 cm −3 , while increasing V [Fe2+] . [ABSTRACT FROM AUTHOR]

Herein Se 2− -doped PbS thin films obtained by using the green chemical bath approach are reported. Morphological, optical and structural properties were investigated by atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and optical absorption. Three impurity levels were prepared by changing the relative volume of the solution containing Se 2− ions in the PbS growing solution. XRD showed growth of all films with the zinc-blende phase. Changes in the grain size (∼27–14 nm) and band gap energy (∼1.4–2.24 eV) were observed. The absorbance in doped films, showing excitonic peaks are due to higher energy transitions from 1 S e → 1 S h . Gibbs energy calculation for the Se 2− doping PbS process was also investigated. [ABSTRACT FROM AUTHOR]

Herein, the growth of PbS doped systematically with solutions containing In 3 + ions by using chemical bath as a green approach is reported, with the aim of studying the effects of such In 3 + -doping on the morphological, structural and some optical properties of the PbS thin films obtained. The morphological changes of the films were followed by Atomic Force Microscopy and Scanning Electron Microscopy. X-ray diffraction studies showed growth in all films of the zinc blende phase. The grain size was found to be ~ 32 nm and ~ 24–14 nm for the undoped and doped samples, respectively. The absorbance results in doped films showed excitonic peaks at ~ 1.6 eV, ~ 1.8 eV, ~ 2.2 eV, owing to higher energy transitions from 1 D h → 1 De, 2 S h → 2 S h and 2 P h → 2 P e , states, respectively. By optical absorption, a shift for the band gap energy was observed from ~ 1.45 eV to ~ 2.18–2.3 eV range for the undoped and doped films, respectively. Gibbs energy calculation for the In 3 + doping PbS process was also examined. [ABSTRACT FROM AUTHOR]

ZnO thin films grown by radio frequency sputtering were studied as a function of the experimental parameters: source power, chamber deposition pressure, substrate temperature and oxygen partial pressure; in addition to post-deposition thermal treatment. The ZnO thin films were characterized by stylus profilometry, optical measurements, electrical resistivity, X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy. Current-voltage and external quantum efficiency measurements were performed on the CdS/CdTe-based solar cell. In the case of ZnO/CdS thin films with a high-temperature thermal treatment, an increment in transmittance was observed in the ZnO wavelength region. With the incorporation of the ZnO thin film in the front contact of the solar cell, we obtained a photovoltaic efficiency of 7.4%, with the following optimal deposition conditions: 230 W source power, 2.67 Pa of deposition pressure and 300°C for the substrate temperature with a thermal treated of 450 °C for ZnO/CdS thin films. While a photovoltaic efficiency of 6.0% was obtained, when the ZnO/CdS was thermal treated at 500°C with the ZnO deposited at 140 W source power, 1.33 Pa deposition pressure and 250 °C for the substrate temperature. Finally, a photovoltaic efficiency of 10% was achieved for CdTe solar cells with ZnO thin film by combining the experimental conditions and the thermal treatment described above. [ABSTRACT FROM AUTHOR]

An Au/Cu2Te/CdTe/CdS/TCO/glass heterostructure based superstrate solar cells with 2.5 mm² of area, where the CdTe layer was prepared by means of closed spaced sublimation (CSS) and the CdS by chemical bath, reached an efficiency (η) value of 12.1%. As transparent conductive oxide (TCO), a thin film of cadmium-indium oxide (CdIn2O4:CIO), obtained by sol-gel technique, was used. A systematic optimization of the thermal activation of the CdTe/CdS/CIO central part of the device with a CdCl2 vapor ambient made the conversion efficiency of the Au/Cu2Te/CdTe/CdS/CIO/glass heterostructure reaches 9.94% for the CdTe layer with thickness of 1.8 μm. This efficiency was reached only through an open circuit voltage (VOC) optimization. A maximum η of 12.1% was reached with the established procedure of optimization and when the CdTe layer thickness was increased to 3.1 ± 0.05 μm. The substitution of CIO by commercial ITO provoked in the cell a decrease of η from 12.1% to 7.2%, both devices prepared under the same conditions. Starting from these results, we can say that CIO was a better TCO than commercial ITO in our solar cell, with the advantage that CIO was obtained by sol-gel, which is a simple and economical technique. [ABSTRACT FROM AUTHOR]

Effects on the optical, electrical, and photocatalytic properties of undoped CuS thin films nanodisks vacuum annealed at different temperatures were investigated. The chemical bath prepared CuS thin films were obtained at 40°C on glass substrates. The grain size of 13.5 ± 3.5nm was computed directly from high-resolution transmission electron microscopy (HRTEM) images. The electrical properties were measured by means of both Hall effect at room temperature and dark resistivity as a function of the absolute temperature 100-330K. The activation energy values were calculated as 0.007, 0.013, and 0.013 eV for 100, 150, and 200°CC, respectively. The energy band gap of the films varied in the range of 1.98 up to 2.34eV. The photocatalytic activity of the CuS thin film was evaluated by employing the degradation of aqueous methylene blue solution in the presence of hydrogen peroxide. The CuS sample thin film annealed in vacuum at 150°CC exhibited the highest photocatalytic activity in presence of hydrogen peroxide. [ABSTRACT FROM AUTHOR]

Abstract: Thin films of the mixed ZnO–SnO2 system were obtained by employing the sol–gel technique, starting from the mixture of zinc oxide and tin oxide precursor solutions. The tin atomic concentration percentages (X) in the precursor solutions with respect to the ZnO+SnO2 total growing solution were: 0, 10, 20, 30, 40 and 100at.%, here, the ZnO atomic percentage is (100–X). The films were deposited by the dip coating method on glass substrates and were sintered at 450, 500 and 550°C, in an open atmosphere. The X-ray diffraction patterns show the presence of zinc oxide and tin oxide crystals. The optical properties of the films were studied by UV–vis spectroscopy. The photocatalytic activity was quantified by means of the bleaching of methylene blue. The films of the mixed ZnO–SnO2 system show higher photocatalytic activity than the SnO2 and ZnO films. [Copyright &y& Elsevier]

TiO thin films were obtained on glass slide substrates by the sol-gel technique. The substrates were coated by the immersion-removal method, at a constant withdrawal speed. The TiO precursor solution and the substrate were maintained in a closed box with a controlled relative humidity (RH) during the removal of the substrate. The RH was varied in the 30-90% range in steps of 20%. The films were dried and after that sintered in an open atmosphere. The effect of the RH was studied on the structural, optical and photocatalytic properties. The films are polycrystalline with an anatase phase and show a high optical transmission in the UV-Vis range. The photocatalytic activity was evaluated by the photobleaching of methylene blue in an aqueous solution. The best photocatalytic activity was obtained for the films with 90% RH, this fact is mainly attributed to the highest porosity value obtained for these films. [ABSTRACT FROM AUTHOR]

Abstract: CdTe thin films were deposited by CSS at a pressure of 1mbar, under different mixtures of argon and oxygen and in vacuum, on glass substrates. The samples were prepared under three source–substrate temperature conditions. The films were characterized by X-ray diffraction, UV–vis spectroscopy, SEM and two-probe resistivity. XRD patterns indicated that the films grown at low oxygen content and source temperature of 550°C with substrate temperature of 400°C showed a high preferential orientation in the (111) plane. The crystalline grain size was between 31 and 40nm. The films had a direct band gap in the range 1.44–1.49eV. SEM images showed higher aggregate sizes for the films deposited at higher temperatures and grain size decreases as oxygen content increases. The resistivity of the films was around 1×106 Ωcm. [Copyright &y& Elsevier]

In this work, we report the synthesis and the structural, optical and electrical properties of undoped tin oxide thin films obtained by the sol-gel technique. The films have been prepared from a simpler precursor solution than other ones reported; it is based on stannous chloride (SnCl·2HO), ethanol, glycerol and triethylamine. The films are deposited on glass slide substrates and sintered at temperatures in the 300-550 °C range, in an open atmosphere. A second thermal treatment in vacuum is made in order to decrease the resistivity of the films. The X-ray diffraction patterns show the tetragonal phase of SnO with a small preferential orientation in the (110) plane. All films show high optical transmission (~85%) and a direct band gap value around of 3.8 eV. The minimum resistivity value, 2 × 10 Ohm-cm, is obtained for the films sintered at 300 and 350 °C and thermal treated in vacuum at 500 °C for 1 h. The decrease of the resistivity with the thermal treatment in vacuum is associated with an increase in the oxygen vacancies concentration. [ABSTRACT FROM AUTHOR]

Abstract: CdS thin films doped with metal-organic salts were grown on glass substrates at 90°C by the chemical bath deposition technique. Metal-organic salts such as zinc acetate, chromium acetylacetonate, ammonium fluoride, aluminum nitrate, tin acetate and indium acetate were used. The chemical bath was prepared with cadmium acetate, ammonium acetate, thiourea and ammonium hydroxide. In the case of un-doped films, the S/Cd ratio was varied by changing the thiourea in the range 1–12. The best optical, structural and electrical properties were found for S/Cd=2. The doped films were prepared by always keeping the ratio S/Cd constant at 2. The band gap (E g) of doped and un-doped films was evaluated from transmittance spectra, where films with lower sulfur concentration exhibited higher E g. X-ray analysis showed that both un-doped and doped films were polycrystalline with preferential orientation along the (111) direction and with the zincblende structure in all cases. The dark electrical results showed that CdS doped with Zn (1at.%) exhibited the lowest resistivity values of 10Ω cm. [Copyright &y& Elsevier]

Abstract: Cadmium indate (CdIn2O4) thin films were deposited on glass substrates by the sol–gel technique, starting from the mixture of two simple precursor solutions of CdO and In2O3 obtained at room temperature. The In atomic concentration percentage (X) in the precursor solution with respect to Cd (1−X) was varied from 55 to 79at% with steps of 4at%. The films were sintered in an open atmosphere at 550°C and after that, exposed to different annealing treatments, 96/4 N2/H2 gas mixture, H2 and vacuum, at different temperatures. X-ray diffraction patterns showed three types of films, consisting of crystals of (a) CdO+CdIn2O4, (b) CdIn2O4 and (c) In2O3+CdIn2O4. It was found that the films with X≤59at% and annealed at 600°C in vacuum for 60min, showed the lowest resistivity, ∼1×10−3 Ωcm. The carrier concentration and mobility were determined from Hall measurements. The films were highly transparent (∼80%) in the 400–1100nm range. In addition to the low-resistivity value and high transparency, the CdIn2O4 films had a direct bandgap around 3.2eV, which shows the importance of using this oxide as a transparent electrode in solar cells. [Copyright &y& Elsevier]

Abstract: Thin films of the mixed CdO-In2O3 system were deposited on glass substrates by the sol–gel technique. The precursor solution was obtained starting from the mixture of two precursor solutions of CdO and In2O3 prepared separately at room temperature. The In atomic concentration percentages (X) in the precursor solution with respect to Cd (1− X), were: 0, 16, 33, 50, 67, 84 and 100. The films were sintered at two different sintering temperatures (Ts) 450 and 550 °C, and after that, annealed in a 96:4 N2/H2 gas mixture at 350 °C. X-ray diffraction patterns showed three types of films, excluding those constituted only of CdO and In2O3 crystals: i) For X ≤50 at.%, the films were constituted of CdO+CdIn2O4 crystals, ii) For X =67 at.%, the films were only formed of CdIn2O4 crystals and iii) For X =84 at.% the films were constituted of In2O3 +CdIn2O4 crystals. In all films in the 0< X <100 range, the formation CdIn2O4 crystals of this material was prioritized with respect to the formation of CdO and In2O3 materials. All films showed high optical transmission and an increase of the direct band gap value from 2.4 (for CdO) to 3.6 eV (for In2O3), as the X value increases. The resistivity values obtained were in the interval of 8×10− 4 Ω cm to 106 Ω cm. The CdIn2O4 films had a resistivity value of 8×10− 3 Ω cm and a band gap value of 3.3 eV. [Copyright &y& Elsevier]

Abstract: We present in this work the degradation effects with time in thin film CdTe/CdS solar cells, where the CdS and CdTe layers are deposited by chemical bath deposition (CBD) and close space vapor transport (CSVT), respectively. The CdS thin films were grown from different baths by varying the S/Cd ratio. The variation of the S/Cd ratio allowed us to control the morphology and the density of defects, thus giving rise to better quality CBD CdS films. Depending on the S/Cd ratio an improvement of the morphology and capacitance signal was observed, these factors have also an influence on the open-circuit voltage, short-circuit current density, fill factor and conversion efficiency of the solar cell. The variation with time of these parameters in our devices was tracked during a period of 3 years measured directly on the exposed back contact regions (CdTe/Cu/Au). A discussion on the deterioration of the photovoltaic (PV) performance of the solar cells is presented in correlation with the local environmental conditions. This particular environment has contamination, and represents another type of stress for standard PV operations. These conditions reduce the mean life time of solar cells beyond short periods; this can be of interest for PV community. [Copyright &y& Elsevier]

Growth of doped CdCO 3 –Pb 2+ thin films was carried out by chemical bath. Changes of the level doping affect the structure and morphology. XRD peaks of CdCO 3 sample show rhombohedral crystalline structure. A-10 and A-20 doped films exhibit peaks that indicate co-existence of one solid solution of CdCO 3 –PbCO 3 Pb(OH) 2 which has rhombohedral crystalline and tetragonal phase respectively, and A-30 film indicate co-existence of CdS–Pb 3 O 2 (SO 4 )(OH) 2 –Pb 4 (CO 2 ) 3 (SO 4 )(OH) 2 compounds. FTIR spectra displayed the peaks at 1400, 850, 718 cm −1 , which are characteristic vibration bands of CO 3 2 − ion and also exhibit an absorption band at ∼670 cm −1 , which is characteristic of Pb–O stretching mode. [ABSTRACT FROM AUTHOR]

Abstract: We study the effects of thiourea concentration on CdS thin films deposited by chemical bath deposition (CBD), submitted to post-thermal treatments of CdCl2, and its effect on the characteristics of CdS/CdTe solar cells. We compare these cells with similar ones fabricated with CdS-films grown by Close Space Vapor Transport (CSVT). The CBD-CdS cells shows higher open circuit voltage (V oc) and fill factor (FF), while the short circuit current remains with little change, as the ratio of S to Cd in the CBD solution goes from 1 to 5. This dependence changes when there is a variation of the CBD-CdS layer thickness. We have obtained cells with more than 12% efficiency when the CdS layers are deposited by the best CBD condition (S/Cd=5) as compared to the best cells with CdS layers prepared by CSVT that had 11% efficiencies. Other measurements such as spectral response were performed and their results were correlated to the I–V characteristics of the solar cells so that the best performances of CBD-CdS solar cells are explained in terms of the chemical composition of this layer. [Copyright &y& Elsevier]

In this work we developed the synthesis and characterization of Sb 2 Te 3 thin films, which were grown by RF as well as DC sputtering as a function of the deposition pressure (P d), 5–15 mTorr. Sb 2 Te 3 films were characterized through X-Ray Diffraction, Energy Dispersive Spectrometry (EDS), Scanning Electron Microscopy (SEM) and electrical resistivity measurements. As a part, contact layer, of the CdTe-based Solar Cell, Current-Voltage (I–V) as well as External Quantum Efficiency (EQE) measurements were carried out. Our results indicate that the radio-frequency sputtered Sb 2 Te 3 are polycrystalline with predominant rhombohedral crystalline structure, whereas the DC-sputtered films crystallized mainly in the monoclinical structure. Both set of samples showed a resistivity of the order of 10−4 Ω-cm. Concerning the CdTe-based solar cell, the incorporation of the Sb 2 Te 3 as a back surface film in the back contact improves the solar cell efficiency up to 8.01%, 10 mTorr pressures into the growth chamber, as compared to the CdTe-based solar cell, 4.82% efficiency, without the Sb 2 Te 3 layer. [ABSTRACT FROM AUTHOR]

Using a powerful argon plasma equipment, 400 °C sintered CuO thin films were rapidly reduced to metallic copper for treatment times less than 35 s. The transformation caused the crystallographic plane of Cu to appear at the expense of the CuO ones. Likewise, transmittance spectra showed a rapid decline while reflectance spectra exhibited a fast increase towards the infrared region. The last effect was caused by the production of free electrons of metallic copper, which was also evidenced by a low electrical resistivity of 30 μΩ∙cm. The plasma-produced Cu samples displayed a fast oxidation rate at room temperature and atmospheric conditions, which has been rarely mentioned in literature. Interestingly, instead of CuO, the oxidation produced Cu 2 O films, which is a p-type semiconductor oxide with high potential for several applications. Even though it only requires some hours, the oxidation was allowed to take place for one week. X-ray diffraction, X-ray photoelectron spectroscopy, transmittance-reflectance, and resistivity measurements demonstrated the oxidation of Cu to Cu 2 O. Similar phenomena were confirmed for lower sintering temperatures of the CuO films. Nevertheless, the oxidation tendency of plasma-obtained Cu films showed a dependence on CuO sintering temperature and on plasma processing time. A stable form of metallic copper, that does not oxidize, was produced at lower sintering temperatures and longer plasma processing times. At other conditions, a metastable form of metallic copper was obtained, which readily transformed to Cu 2 O. Based on the results, a transformation pathway scheme was elaborated. The scheme can provide with a route to rapidly produce high quality Cu 2 O films on glass with tunable electrical and optical properties. • CuO is rapidly reduced to Cu by heat and electricity under plasma bombardment. • Produced Cu naturally oxidizes to Cu 2 O in a rate uncommonly reported before. • Cu stability depends on sintering temperature of target CuO and plasma time. • Resistivity presents great variation with the presence of CuO, Cu 2 O and/or Cu. • XPS and reflectance are crucial to prove the transformation of CuO to Cu 2 O. [ABSTRACT FROM AUTHOR]

ZnO films prepared on glass substrates at T = 80 °C ± 3 °C using the chemical bath deposition technical. The precursor solutions was KOH (0.5 M), NH 4 NO 3 (1.5 M) using three different Zn(NO 3 ) 2 (0.2 M, 0.3 M, 0.4 M) concentration. The morphology is investigated by Scanning Electron Microscopy (SEM) and images shows porous matrix with cavities of different size, javelin and tretrap. According to the XRD diffractograms, all the nanocrystals present hexagonal crystalline phase with grain size of ∼33.4 nm, ∼36.5 nm and ∼34.2 nm. The samples present typical stress in these films. Absorbance spectrum exhibits a characteristic band of the nanocrystals, band gap energy shows a shift in the range ∼3.7–3.8 eV associated with decreasing grain size, as well as the quantum confinement effect in this case of nanocrystalline material. Photoluminescence shows bands, associated with the existence of interstices and vacancies of oxygen and Zinc respectively. Analysis of chemical reactions is performed using the Nernst equation to quantify changes ΔG° to predict the spontaneity of the reactions. [ABSTRACT FROM AUTHOR]

The growth of PbS nanocrystals doped in situ simultaneously with Er 3+ -Cd 2+ -Bi 3+ solutions at different proportions was examined with the aim of investigating the morphological, optical and structural changes of the nanocrystals obtained. A brief summary of the chemical equilibria plus the Gibbs free energy changes are presented. Fourier transform infrared spectroscopy (FTIR) spectra showed an absorption band located at ~ 3356 cm −1 attributed to stretching of -OH groups and a sharp stretching band at ~ 1932 cm −1 assigned to vibration mode of C O 3 2 − ions.This absorption bands are generally due to the decomposition of thiourea in alkaline medium. X-ray diffraction (XRD) patterns exhibited a cubic phase in all films and the grain size (GS) of the undoped samples was ~6.57 nm, whereas for doped films was ~ 6.40–4.16 nm. Transmission Electron Microscopy (TEM) confirmed the structural characteristics of the nanocrystals. Absorbance spectra of PbS films exhibited five absorption bands located at ~ 346, ~ 585, ~ 615, ~ 670 and ~ 775 nm due to strong confinement effect. This multiplex of bands presented in PbS is induced by the simultaneous incorporation of the ions. The shift of the band gap energy is associated with the decrease of crystalline size in PbS films. On the other hand, a small absorption band located at ~ 446 nm, corresponding to 4 F 7/2 → 4 I 5/2 (4 f → 4 f transitions of Er 3+ ions) was also observed. A small blue emission band centered at ~ 446 nm was originated from the allowed 3 P 1 → 1 S 0 transition of Bi 3+ ions. Band gap energy of nanocrystals showed a shift in the ~ 1.4–2.6 eV range. The structural experimental results are associated with the optical changes confirming the gradual incorporation of the dopant ions in the crystallites network. Raman spectra showed two bands located at ~ 450 cm −1 due to the first overtone of the LO phonon (2LO) and other band located at ~ 200 cm −1 which has been attributed to the LO (Γ) phonon,confirming the existence of doped-PbS nanocrystals. [ABSTRACT FROM AUTHOR]

In this work, TiO 2 and CdO + CdTiO 3 multicomponent oxide thin films growth was performed with different Ti/Cd ratios (0, 0.20, 0.49, 0.60, 0.65, 0.70 and 1) by the sol–gel route in order to degrade benzene in gas phase with an initial concentration level of 110 ± 10 ppm, under different conditions of relative humidity (RH): 25%, 50% and 80% in a batch type reactor, at room temperature. The results showed a degradation near to 100% at t = 75 min, using the CdO + CdTiO 3 multicomponent oxide semiconductor with a Ti/Cd ratio of 0.65. On the other hand, the TiO 2 thin films reached only a degradation of 70% in t = 240 min. A decrease of the oxidation process of benzene was observed in all films studied, as the relative humidity increased. [ABSTRACT FROM AUTHOR]

In this work Cd 2 SnO 4 polycrystalline thin films with cubic phase were deposited on glass substrates by the sol–gel technique starting from the mixture of two simple precursor solutions of CdO and SnO 2 , obtained at room temperature. Both solutions were prepared using metallic salts, cadmium acetate and stannous chloride. The Sn atomic concentration percentages ( X ) in the precursor solution with respect to Cd (1− X ) were 16, 25, 29, 33, 36 and 40. The films were sintered at 550 °C in air and, after that, exposed to two different annealing treatments, 96/4N 2 /H 2 gas mixture and vacuum, at 350 °C and 550 °C, respectively. X-ray diffraction patterns of the films without annealing showed three types of films: i) for X <29 at%, the films were constituted of CdO+Cd 2 SnO 4 crystals, ii) for X =29 at% and X =33 at%, Cd 2 SnO 4 polycrystalline thin films were obtained, and iii) for X >33 at%, Cd 2 SnO 4 + CdSnO 3 crystals were formed. Cd 2 SnO 4 films maintained the spinel-type crystalline structure of the Cd 2 SnO 4 after the annealing processes. On the other hand, Electron Dispersion Spectroscopy measurements revealed that Cd 2 SnO 4 films obtained at X =29 at%, without annealing, had a Cd/Sn ratio nearest to the one of the Cd 2 SnO 4 compounds. With and without annealing Cd 2 SnO 4 films showed high optical transmission ~85% in the 500 nm< λ <1500 nm range. A minimum resistivity value was around 2×10 −3 Ω cm, which was obtained for Cd 2 SnO 4 films ( X =33 at%) annealed in vacuum at 550 °C, and a direct band gap energy value of 3.55 eV. As a test of the quality of these films as transparent electrodes, Au/Cu 2 Te/CdTe/CdS/Cd 2 SnO 4 /glass solar cells were obtained with average efficiency of 10.7%. [ABSTRACT FROM AUTHOR]

Abstract: In the preparation of CdO+CdTiO3 polycrystalline thin films by the sol–gel method, the optical, structural and crystalline properties, as well as the photocatalytic activity (PA) depends strongly on the sintering temperature (Ts) of the films and of the Ti/Cd ratio used in the precursor solution. In this work, CdO+CdTiO3 thin films were prepared using a Ti/Cd constant ratio in the precursor solution. The films were sintered at six different Ts in the 450–550°C range, in an open atmosphere. The structure of the films was characterized by X-ray diffraction and the PA was evaluated by the photobleaching of methylene blue in an aqueous solution using a UV–vis spectrometer. The relative intensity of the diffraction peaks associated with CdO and CdTiO3, change with the Ts. The better photocatalytic activities were obtained for the films sintered at 490°C and 550°C. When the CdO was removed from the films by chemical etching the PA decreased, showing the importance of coupling both oxides. [Copyright &y& Elsevier]

Abstract: Undoped and fluorine doped cadmium oxide films were obtained by the sol–gel technique, starting from a simple precursor solution constituted of: cadmium acetate, methanol, glycerol and triethylamine and only for doped samples, ammonium fluoride as the fluoride source. Due to the methanol content used is higher with respect to the other reagents, variations in this parameter affect the viscosity and gelation time of the precursor solution, giving as result changes in the thickness. The importance of the methanol content in the growing solution on the structural, morphological, optical and electrical properties of the films is reported. Higher thickness was obtained for lower methanol content, in the range 33–46mol, in the growing solution. Largest growing rate was obtained when the methanol content in the precursor solution was 33mol. The films showed good characteristics for their use as transparent conductive films in solar cells. [Copyright &y& Elsevier]

Abstract: Undoped thin films of the (CdO)1−X +(TiO3) X system were prepared on glass substrates using the sol–gel technique. The precursor solution was obtained starting from the mixture of two precursor solutions for CdO and TiO2 prepared separately. The Ti and Cd atomic concentrations in the precursor solution, X and (1− X), respectively, were varied in the range 0.20≤ X ≤0.65. The films were sinterized at 450°C in open atmosphere. X-ray diffraction, photoacoustic (PA) and Raman spectroscopies, atomic force microscopy, optical absorption and reflectivity, both in the intermediate infrared region, and dark resistivity (ρ) measurements were carried out for characterization. The films present predominantly the monteponite cubic phase of CdO for X ≤0.30. The ilmenite rhombohedrical crystalline phase of CdTiO3 predominates for X >0.30. The oxide formed is a mixture of CdO and CdTiO3. The energy band gap (E g), measured from PA data, changes abruptly from 2.5eV to 3.5eV when X ≅0.40, and the maximum E g =3.70eV was observed when X =0.55. ρ also experiences a steep variation of eight orders of magnitude when X ∼0.40. The photocatalytic activity was found to be maximum for X =0.40. The resultant oxide displays some physical properties different of a simple mixture of materials. [Copyright &y& Elsevier]

Abstract: ZnO+Zn2TiO4 thin films were obtained by the sol–gel method, the precursor solutions were prepared using two Ti/Zn ratios: 0.49 and 0.69. The films were deposited on glass slide substrates and sintered at temperatures in the 200–600°C range in increments of 50°C, with the goal of studying the dependence of the photocatalytic activity (PA) on the annealing temperature. The films were characterized by X-ray diffraction and UV–Vis spectroscopy. The PA was evaluated by measuring the UV–Vis absorption spectra of the methylene blue in aqueous solution before and after photobleaching, using the Lambert–Beer''s principle. The higher photocatalytic activities were obtained from the films with sintering temperature around 450°C, for both Ti/Zn ratios studied. [Copyright &y& Elsevier]

Abstract: Chemically sprayed aluminum-doped zinc oxide thin films were deposited on glass substrates. The effect of the deposition conditions and the post annealing treatment in vacuum on the electrical, optical, structural and morphologic properties have been analyzed. The films were prepared using two Zn reactants, namely zinc acetate A(Zn) and zinc pentanedionate P(Zn). Aluminum pentanedionate P(Al) was used as the dopant source in both cases. The results show that the doping and annealing of the ZnO thin films enhance mainly the electrical properties. Under optimum deposition conditions a low resistivity and a high optical transmittance of the order of 1.8×10−2 Ω cm and 85%, respectively, were obtained. No significant changes in the optical properties were observed as a consequence of the annealing treatments. All the films show a crystalline structure with a preferred (002) growth i.e. the c-axis is oriented normal to the substrate plane in all the cases. [Copyright &y& Elsevier]

Abstract: Thin films of the mixed CdO–TiO2 system were prepared on glass substrates using the sol–gel technique. The precursor solution was obtained starting from the mixture of two precursor solutions of CdO and TiO2 prepared separately. The Ti and Cd atomic concentrations in the precursor solution, X and (1–X), respectively, were varied in the range . The films were sinterized at 450°C in open atmosphere. X-ray diffraction and photoacoustic spectroscopy techniques were used for characterization. The films present predominantly the Monteponite cubic phase of CdO for , and the Ilmenite rhombohedrical crystalline phase of CdTiO3 for . The energy band gap (E g) as a function of X was analyzed, and the maximum was observed when . [Copyright &y& Elsevier]

Abstract: Indium-doped zinc oxide thin films were deposited on glass substrates by the chemical spray technique. Hydrated zinc 2,4-pentanedionate was used as zinc source. Four different indium compounds were separately used as dopants (indium nitrate, indium sulfate, indium acetate, and indium chloride). The effect of the thickness on the electrical, structural, morphological and optical characteristics of ZnO:In thin films was studied. Electrical resistivity values corresponding to good conductive electrodes were obtained irrespective of the indium compound used, although a decrease in electrical resistivity is found in all the cases as the film thickness increases, reaching a saturation value of 2×10−3 Ωcm. All films were polycrystalline with a wurtzite phase, and exhibited a (101) preferential orientation almost irrespective of neither the doping source nor thickness. The surface morphology was analyzed by scanning electron microscopy and a strong dependence on the indium compound and thickness was found, since grain geometry variations from rounded to rod-like forms were observed. As the film thickness increases, the film transmittance and the band-gap values decrease. Band-gap energy values were in the range of 3.21 to 3.44eV. [Copyright &y& Elsevier]

Abstract: The heterostructure design proposed by us for the photovoltaic (PV) solar cell is: Au–Cu/p–CdTe:Sb/n–CdO:F/glass. The CdO:F films were grown by the sol–gel method, in conditions in order to get low resistivity ∼4.5×10−4 Ω-cm and an optical transmission higher than 85%. The CdTe:Sb films were prepared by means of the RF sputtering technique, in conditions to get resistivity value around 106 Ω-cm, high crystalline quality and higher grain size. The Au–Cu contacts were thermally evaporated. For the study of PV-heterostructure a systematic variation of the preparation parameters were carried out. The parameters involved in the manufacture of the cell, in order to look for the highest efficiency were: (A) For the deposit of the p-CdTe:Sb films, a low argon pressure of 2.5mTorr and high substrate temperature of 450°C. The CdTe:Sb film thickness was varied in the interval 4.5–11μm. (B) For the activation of the heterostructure: (i) The treatment temperature in vacuum, after the CdTe is deposited, was varied in the 350–550°C range and (ii) the treatment temperature in Ar atmosphere, after the heterostructure is dipped in CdCl2 solution, was studied in the 400–510°C range. (C) Optimization of the Cu–Au contact with the adequate Cu-film thickness. The highest energy conversion efficiency (η) value was 5.48%. This work reports a systematic study of the parameters involved in the solar cell manufacture, for the search of a better value of η. [Copyright &y& Elsevier]

Abstract: We have grown CdS films by the Close Spaced Vapor Transport technique under specific conditions: substrate temperature (): 450°C, source temperature (): 725°C, argon pressure in the chamber (): 100, 200 and 500mT, deposition time (): 100s. The films were studied by measuring the luminescence properties at different temperatures in the range 10–300K. The room-temperature PL spectrum of the as-grown CdS films showed a very broad band centered at 2.26eV and a shoulder in the low-energy side at 1.80eV. After CdCl2 thermal annealing at 300K, the spectrum showed better PL characteristics: a strong band in the low-energy side at 1.67eV and a band in the high-energy side at 2.47eV. The analysis at lower temperatures showed that the high-energy band becomes most intense and shifts to higher energies reaching a value of 2.54eV, very close to the energy band gap at 10K. The low-energy band becomes broader and centered around 1.9eV. Analysis of the PL intensity as a function of temperature in an Arrhenius representation, allows applying a theoretical model for the quenching of the PL intensity. [Copyright &y& Elsevier]

Abstract: R.F. sputter deposition of Sb doped CdTe thin films was carried out with targets containing different amounts of antimony (C T: 0, 2.5, 10 and 20at.%). The substrates were kept at different temperatures (T s) of 200, 275, 350 and 450°C. Three different argon pressure values: 2.5, 5 and 15mTorr were used. The lowest dark resistivity (ρ) at room temperature (RT) was 9.0×105 Ωcm, which is one of the lowest values reported in the literature for Sb doped CdTe. Highly transparent (∼90%) and conductive (ρ =3.7×10−4 Ωcm) F doped CdO (n-type) thin films, prepared at room temperature by the sol–gel method, were employed as window and top-contact. The configuration of the fabricated solar cell was (Au–Cu)/p-CdTe/n-CdO/glass. Open-circuit voltage (V oc) and short-circuit current density (J sc) at room temperature have the highest values for high T s, low P g and C T =10at.%. Despite the fact that V oc and J sc are lower than those reported in the literature, we think this work is useful as a basis for the search of more competitive CdTe/CdO based PV devices. [Copyright &y& Elsevier]

The superficial morphology and porosity of metal oxide films play an important role in their sensing response to the presence of organic vapors. For films deposited from precursor solutions, both can be modified by varying the solution's molarity and thickness; however, their effect on the film's sensitivity has been scarcely studied in p-type materials. In this work, CuO p-type nanostructured films on glass substrates were obtained from three precursor solutions at different molarities. The films were deposited by dip-coating, varying the coats to obtain thicknesses in the 100–1700 nm wide range. Scanning electron microscopy images show surfaces with higher porous presence as the film's thickness and precursor solution molarity increase. The CuO films were tested as acetone-vapor sensors in a wide concentration range from 1 to 2000 ppm at a sample temperature T s = 300 °C. Their sensitivity (S) grows as the film thickness increases, regardless of the solution molarity, associated with a higher porosity, calculated from refractive index values. The highest response is obtained for CuO thickest film (τ = 1670 nm) deposited from the solution at the highest molarity. S values of 1.3, 3.4, 4.75, and 7.4 are obtained at 1, 100, 300, and 2000 ppm acetone-vapor concentrations, respectively. These S values are inside the reported ones using more sophisticated techniques and processes. [Display omitted] • Dependence of the p-type metal oxide film thickness on its acetone vapor sensing. • CuO film acetone sensors with good sensitivity from a based-solution simple technique. • CuO films as acetone sensors in wide ranges of thickness and vapor concentration. [ABSTRACT FROM AUTHOR]