Cadmium Stannate Films Research Articles

Cadmium Stannate Films for Immobilization of Phospholipid Bilayers

Cadmium tin oxide (CTO) films on glass substrates were synthesized and functionalized by octadecyltrichlorosilane (OTS). CTO films were transparent with the bandgap of 2.92 eV. They exhibited n-type conductivity and carrier concentration of (3.31 ± 0.38) · 1019 cm−3. Weak temperature dependence points out to a nearly degenerative state of the carriers in the CTO films. Silanization by OTS yielded hydrophobic surface with the contact angle values reaching 103 ± 12 degrees. Silanization of films was followed by a significant reduction of the interfacial capacitance, which upon completion of the functionalization reached levels below 3 μF cm−2. The value of the electric capacitance as well as data of ATIR absorption, hints at sparse and disordered coverage of the CTO surface by octadecylalkylsilane molecules. Such organic layer, however, was able to trigger phospholipid (60% dioleoylphosphocholine and 40% cholesterol) vesicle rupture and the formation of a secondary layer of phospholipid, thus rendering hybrid bilayer surface construct. Such hybrid constructs may be useful in applications where electrode coupling to a model biological membranes and membrane bound proteins is required, such as biosensing and photovoltaics.

Sol-gel processing of highly transparent conducting Cd2SnO4thin films

Polycrystalline thin films of cadmium stannate (Cd2SnO4) (CTO) were coated on corning glass substrates by sol-gel method. The films were fired at different temperatures and annealed in inert ambient (N2) at 680°C. The structural, optical, and electrical properties of dip-coated cadmium-tin-oxide (CTO) thin films are discussed. CTO layers with a Hall mobility of 30 cm2/Vs and a carrier density of 1.4 × 1021 cm−3 resulting in a resistivity of 5 × 10−4 Ω cm have been deposited. Dip-coating conditions must be carefully monitored to produce consistent films. The high electronic conductivity is due to two effective mechanisms of n-type doping: (i) stoichiometric deviation and (ii) self-doping.

Effect of annealing on the electrical, optical and structural properties of cadmium stannate thin films prepared by spray pyrolysis technique

Polycrystalline thin films of cadmium stannate (Cd 2SnO 4) were deposited by spray pyrolysis method on the Corning substrates at substrate temperature of 525 °C. Further, the films were annealed at 600 °C in vacuum for 30 min. These films were characterized for their structural, electrical and optical properties. The experimental results showed that the post-deposition annealing in vacuum has a significant influence on the properties of the films. The average grain size of the film was increased from 27.3 to 35.0 nm on heat treatment. The average optical transmittance in the visible region (500–850 nm) is decreased from 81.4% to 73.4% after annealing in vacuum. The minimum resistivity achieved in the present study for the vacuum annealed films is the lowest among the reported values for the Cd 2SnO 4 thin films prepared by spray pyrolysis method.

Preparation of cadmium stannate films by spray pyrolysis technique

Abstract Cadmium stannate thin films were prepared by spray pyrolysis technique using cadmium acetate and tin(II) chloride precursors at substrate temperatures 450 °C and 500 °C. XRD pattern confirms the formation of orthorhombic (1 1 1) cadmium stannate phase for the film prepared at substrate temperature of 500 °C, whereas, films prepared at 450 °C are amorphous. Film formation does not occur at substrate temperature from 300 to 375 °C. SEM images reveal that the surface of the prepared Cd2SnO4 film is smooth. The average optical transmittance of ∼86% is obtained for the film prepared at substrate temperature of 500 °C with the film thickness of 400 nm. The optical band gap value of the films varies from 2.7 to 2.94 eV. The film prepared at 500 °C shows a minimum resistivity of 35.6 × 10−4 Ω cm.

Spray-pyrolysis Cd 2SnO 4 films for electrochemical applications

Conductive cadmium stannate (Cd 2SnO 4,) films were grown by a simple spray-pyrolysis technique using aerosols ultrasonically generated from solutions containing Cd(thd) 2(TMEDA) and n Bu 2Sn(AcAc) 2, and monoglyme as solvent (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate, TMEDA = N, N, N′, N′-tetramethylethylenediamine, AcAc = acethylacetonate). The overall film growing procedure was carried out at or below 400 °C thus allowing low-melting temperature materials like glass to be used as film substrates. Typical resistivity values of Cd 2SnO 4 films were found to be ∼ 2 · 10 −3 Ωcm. The films exhibit excellent electrochemical activity with comparable or higher electron transfer rates than cadmium stannate films obtained via sol–gel methods at high annealing temperature.

Pulsed Laser Deposition of Crystalline Cd2SnO4 Thin Film

Thin films of cadmium stannate (Cd2SnO4) have been deposited on glass substrates by pulsed Nd:YAG laser at room temperature. The deposited film was crystalline in nature and highly oriented in the (311) direction. Using this method, Cd2SnO4 films with the Hall mobility of 25 cm2 V-1 s-1 and the carrier concentration of 6× 1020 cm-3 corresponding to the conductivity of 2.4× 103 S cm-1 have been prepared without post-deposition thermal annealing. The films exhibited average optical total transmission of 70% in the visible region. The optical band gap was found to be 3.18 eV. [DOI: 10.1380/ejssnt.2007.152]

Measurement of the Effective Mass of Transparent Conducting films of Cadmium Tin Oxide

ABSTRACTWe have prepared transparent conducting films of cadmium stannate (Cd2SnO4 with resistivity as low as 1.5×10-4 Ω cm. The resistivity of these films is low because of their surprisingly high mobility (60 cm2 V-1 sec-1) at high carrier concentration (7×1020cm-3). We conducted an investigation to determine whether the high mobility is due to unusually low carrier effective mass or to a long carrier relaxation time. The conductivity effective mass and relaxation time were estimated by Drude free-electron modeling of reflectance and transmittance spectroscopie measurements. The Drude model appears to represent the behavior of cadmium tin oxide very well. The optical effective mass of the electrons in cadmium stannate is about 0.35 mo, which is similar to that of other transparent conducting oxides. By varying the doping level, we were able to fabricate films with various levels of degeneracy, but these showed no significant difference in effective mass.We were also able to determine the carrier effective mass and the relaxation time by measuring four separate electron transport coefficients: conductivity, Hall, Seebeck, and transverse Nernst-Ettingshausen (Nernst). The Fermi level was found to vary from 0.31 to 0.83 eV above the conduction band minimum, and the conduction band was very close to parabolic in this range, with m* ∼ 0.33 mo, in good agreement with the optical result. We conclude that the effective mass of electrons in cadmium stannate is similar to electrons in other transparent conducting oxides and that high mobility results from a relatively long carrier relaxation time.

Recent developments in RF sputtered cadmium stannate films

A method for producing single-phase cadmium stannate thin films is reported. Polycrystalline films were prepared by RF sputtering onto water-cooled Corning glass substrates, followed by a high temperature anneal. Resistivities as low as 1.28 × 10 −4 ohm·cm have been achieved, lower than any previously published results, for this material. Even with sheet resistivities as low as 2.5 ohm sq −1, exceptionally high film transparency (∼85%) is maintained, with very low absorption in the visible spectrum.

Enhanced IR reflectance of cadmium stannate films prepared by DIP coating

Enhanced IR reflectance of cadmium stannate films prepared by DIP coating

Properties of two-phase cadmium stannate thin films

Thin films of cadmium stannate were prepared from a Cd 2SnO 4 target by r.f. sputtering. Optical and electrical properties were studied as functions of film thickness and related to changes in composition and structure; in particular, the presence of both amorphous and crystalline phases within the same film was demonstrated for the first time. The surface composition of the films, in contrast to the bulk composition, was shown to be significantly affected by heat treatment, with clear implications for the use of cadmium stannate as a transparent conductor in electronic devices. It is concluded that failure to control adequately parameters such as deposition temperature can lead to non-uniformity of structure and properties within a single run and variability from one run to another.

Optical properties of cadmium stannate thin film prepared by pyrolytic process

Thin films of cadmium stannate are prepared by spray pyrolysis technique with thickness less than 1 μm. Optical transitions were analysed in terms of the imaginary part of dielectric constant giving rise to direct allowed transition of 2.81 eV, indirect allowed transition of 2.15 eV together with assisting phonon of 0.058 eV. The electronic transitions are also estimated from the variation of refractive index and extinction coefficient with photon energy.

119Sn M�ssbauer spectroscopic study of cadmium stannate films prepared by dip-coating

119Sn M�ssbauer spectroscopic study of cadmium stannate films prepared by dip-coating

Electroless deposition of cadmium stannate, zinc oxide, and aluminum-doped zinc oxide films

Transparent conducting films of cadmium stannate (Cd2SnO4), zinc oxide, and aluminum-doped zinc oxide have been made by a simple, economical electroless deposition technique. The as-deposited films of cadmium stannate have a 75% transmittance in the visible, 48% reflectance in the IR, and a band gap of 2.7 eV. Its resistivity is ∼10−1 Ω cm. Vacuum annealing changes the transmittance in the visible range to 82%, the IR reflectance to 62%, and the band gap to 3.1 eV. The corresponding values for the hydrogen-annealed films are 87%, 76%, and 3.2 eV. Annealing lowers the resistivity of the films to ∼10−2 and ∼10−3 Ω cm for vacuum and hydrogen-annealed films, respectively. The undoped zinc oxide films have transmittance in the visible and reflectance in the IR of 80 and 67% respectively. Aluminum doping increases the transmittance to 88% and reflectance to 83%. The optical band gap of undoped and aluminum-doped zinc oxide films are found to be 3.40 and 3.98 eV, respectively. The resistivity is 1.20×10−2 and 6.0×10−2 Ω cm for undoped and aluminum-doped ZnO films. Vacuum annealing reduces the resistivity of the films to 2.5×10−3 and 2.1×10−4 Ω cm for undoped and aluminum-doped ZnO films, respectively.

Properties of cadmium stannate thin films produced by reactive high rate d.c. magnetron-plasmatron sputtering

Reactive d.c. plasmatron sputtering of Cd 2Sn targets in an ArO 2 gas mixture allows the production of cadmium stannate films. We found ranges of the discharge power and of the pressure ratio p O 2 p tot as coating parameters that yield highly transparent and electrically conductive films at a substrate temperature ϑ s of about 30°C. The deposition rates were greater than 6 nm s −1. The most important film properties measured at a constant discharge power P = 450 W as functions of the pressure ratio p O 2 p tot are given.

Spray deposition and characterization of cadmium stannate films for solar cells

Cadmium stannate films were deposited by spray pryolysis into pyrex glass, starting from an aqueous solution of CdCl2 plus SnCl4 without doping. Structural, optical, and electrical properties were investigated. The films show high optical transparency and an electrical conductivity up to 1.1×102 Ω−1 cm−1. The effect of postdeposition heat treatment under hydrogen was investigated.

Spray Deposition of Cadmium Stannate Films

The feasibility of spray coating transparent cadmium stannate electrodes onto glass has been demonstrated. Both cadmium stannate phases, and , can be deposited. The lowest electrical sheet resistances (10–20 Ω/□) and good optical transparency were obtained in films. With, clear films having 80–100 Ω/□ were achieved.

Evaluation of cadmium stannate films for solar heat collectors

Optical transmission and reflection data are reported for Cd2SnO4 films coated onto transparent substrates or silicon. It is shown that these coatings are candidates for transparent heat reflectors and selective absorber components in solar heat collectors.

Properties of cadmium stannate films prepared by r.f. sputtering from powder targets

Abstract The composition, electrical conductivity and optical transmission of sputtered thin films of Cd2SnO4 were studied in relation to r.f. sputtering power and deposition rate and also in relation to the effects of post-deposition heat treatment. Sputtering conditions can be varied to give a stoichiometric cadmium:tin ratio in the film at which the conductivity is shown to have a maximum value. Design data are given relating the transmission of coated soda glass to film resistance in ohms per square.

CdS ‐ Cu2 S Solar Cells Fabricated on Cd2SnO4 ‐ Silica Substrates

Cadmium stannate films of 1Ω per square sheet resistance and 85% average transmissivity (500–650 nm) have been grown by means of rf sputtering onto silica substrates. thin film solar cells with conversion efficiencies greater than 5% for front and rear illumination have been fabricated. The reflection of transmitted light back through the cell has increased the light generated current. Fabrication techniques are described and current‐voltage and spectral response measurements are presented for frontwall and backwall modes of operation.