Tin Doped Zinc Oxide Research Articles

H2S gas sensitive Sn-doped ZnO thin films: Synthesis and characterization

Tin doped zinc oxide thin films were synthesized at low substrate temperature (473K) by advanced spray pyrolysis technique for H2S gas sensing application. Equimolar solution of zinc acetate and tin chloride were used to grow Sn doped ZnO thin films. The effects of tin doping concentration on the structural, morphological, and gas sensing properties of Sn doped ZnO films were investigated. It is revealed that all films exhibit wurtzite structure and the average crystallite size reduce with increasing Sn doping concentration. With an increase in Sn doping, the peak position of the (002) plane was shifted to the low 2θ values indicating the lattice distortion incorporated into the film due to Sn doping. The results obtained from TEM and FESEM characterizations confirmed the XRD observations. Further, the as-characterized Sn doped ZnO films were profoundly studied for their H2S sensing performance. The H2S gas sensing characteristics that are mainly governed by an operating temperature were found to be optimum at 473K. A maximum response of ∼31% to 30ppm H2S was obtained at 473K with reasonably fast response and recovery. Particularly, the 4wt.% Sn doped ZnO sample exhibits selective behavior towards H2S on account of its surface morphological features. The H2S detection properties of the 4wt.% Sn doped ZnO film were improved significantly on palladium (Pd) sensitization and the film demonstrated adequately stable sensing performance.

Fluorine doped zinc tin oxide multilayer transparent conducting Oxides for organic photovoltaic׳s Cells

Few nm of Ag layer embedded in fluorine doped zinc tin oxide FZTO/Ag/FZTO was fabricated on glass by radio frequency magnetron sputtering at room temperature for the applications of organic photovoltaic׳s cells. The structural, electrical and optical properties of FZTO thin films were investigated. The multilayer of the FZTO (40nm)/Ag (9nm)/FZTO (40nm) electrode shows the maximum optical transmittance (λ=380–770nm) of 88.15%, quite low electrical resistivity of ~8×10−5Ω cm and the corresponding figure of merit (T10/Rsq) is equivalent to 3.46×10−2Ω−1. A normal organic photovoltaic׳s (OPV) structure of poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b]dithiophene-2,6-diyl][3-fluoro-2-[(2 ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl] (PTB7): phenyl-C70-butyric acid methyl ester (PC70BM) was fabricated on glass/FZTO/Ag/FZTO to examine the compatibility of OPV as a transparent conducting electrode. The bulk hetero-junction organic photovoltaic׳s device fabricated on the multilayer FAF electrode exhibited open circuit voltage (Voc) of 0.72V, a short circuit current (Jsc) of 12.28mA/cm2, a fill factor (FF) of 0.54. These properties are analogous to Voc=0.75V, Jsc=14.87mA/cm2, FF=0.53 on commercial indium tin oxide (ITO). A resultant power conversion efficiency of 4.84% is comparable with the 5.90% of the same OPV structure on the commercial ITO as a reference. This reveals that FZTO/Ag/FZTO multilayer electrode is a promising electrode scheme for bulk hetero-junction organic photovoltaic׳s cells (BHJ-OPVs).

Hydrogen plasma treatment for improved conductivity in amorphous aluminum doped zinc tin oxide thin films

Improving the conductivity of earth-abundant transparent conductive oxides (TCOs) remains an important challenge that will facilitate the replacement of indium-based TCOs. Here, we show that a hydrogen (H2)-plasma post-deposition treatment improves the conductivity of amorphous aluminum-doped zinc tin oxide while retaining its low optical absorption. We found that the H2-plasma treatment performed at a substrate temperature of 50 °C reduces the resistivity of the films by 57% and increases the absorptance by only 2%. Additionally, the low substrate temperature delays the known formation of tin particles with the plasma and it allows the application of the process to temperature-sensitive substrates.

High‐performance full transparent tin‐doped zinc oxide thin‐film transistors fabricated on glass at low temperatures

High-performance full transparent bottom-gate type tin-doped zinc oxide thin-film transistors (TZO TFTs) had been successfully fabricated by RF magnetron sputtering on glass substrates at low temperatures. The effect of O2/Ar gas flow ratio during channel deposition on the electrical properties of TZO TFTs was investigated and an optimised growing condition (O2/Ar gas flow ratio: 8/92) for TZO film as the channel layer was acheived. Excellent device performance was obtained, with a low off-state current (I off) of 10−12 A, a high on/off current ratio of 5 × 107, a high saturation mobility (μ s) of 57 cm2/Vs, a steep subthreshold slope of 0.507 V/decade and a threshold voltage (V th) of 3.5 V. These results highlight that excellent device performance can be realised in TZO film and TZO TFT is a promising candidate for transparent flat panel display.

Role of solvent volume on the structural and transparent conducting properties of SnO2: Zn films

Zinc doped tin oxide (ZTO) films were deposited from starting solutions having different solvent volumes (10, 20 … 50 mL), using a simplified spray pyrolysis technique. The effects of solvent volume on the structural, electrical, optical and surface morphological properties were investigated. From the structural studies, it is observed that the preferential orientation is along the (200) plane for lower solvent volumes and it turns in favour of (101) plane for the higher solvent volume levels (40 and 50 mL), indicating the stable p-type conductivity. Electrical studies show that the sheet resistance (Rsh) increases as the solvent volume increases. The minimum sheet resistance (4.32 kΩ/sq.) is obtained in the case of minimum solvent volume (10 mL). The Hall measurements reveal that the type inversion takes place beyond 30 mL of solvent volume. The optical transmittance increases as the solvent volume is increased and it is found to be in the range of 80–95 %.

Structural and electrical properties of fluorine-doped zinc tin oxide thin films prepared by radio-frequency magnetron sputtering

Transparent and conductive thin films of fluorine doped zinc tin oxide (FZTO) were deposited on glass substrates by radio-frequency (RF) magnetron sputtering using a 30 wt% ZnO with 70 wt% SnO2 ceramic targets. The F-doping was carried out by introducing a mixed gas of pure Ar, CF4, and O2 forming gas into the sputtering chamber while sputtering ZTO target. The effect of annealing temperature on the structural, electrical and optical performances of FZTO thin films has been studied. FZTO thin film annealed at 600 °C shows the decrease in resistivity 5.47 × 10−3 Ω cm, carrier concentration ∼1019 cm−3, mobility ∼20 cm2 V−1 s−1 and an increase in optical band gap from 3.41 to 3.60 eV with increasing the annealing temperatures which is well explained by Burstein–Moss effect. The optical transmittance of FZTO films was higher than 80% in all specimens. Work function (ϕ) of the FZTO films increase from 3.80 eV to 4.10 eV through annealing and are largely dependent on the amounts of incorporated F. FZTO is a possible potential transparent conducting oxide (TCO) alternative for application in optoelectronics.

Structural and optical properties of TZO thin films

In this paper, the synthesis route and growth mechanism of ZnO nanowhiskers and multipods are investigated. A simple chemical deposition route is used to synthesize tin doped zinc oxide (TZO) nanostructures using a horizontal quartz furnace. To study the effect of tin doping on the morphology of ZnO thin film, nanostructures with different morphologies and sizes were grown on silicon wafers and ITO substrates using thermal evaporation of a mixture of zinc, tin, and graphite powders at 1000 °C in a pure oxygen atmosphere. Structural studies of the synthesized ZnO nanostructures were done by means of XRD, SEM, and HRTEM. An XRD graph confirmed the formation of a pure ZnO phase. The SEM and HRTEM images exhibited nanowhiskers with dimensions of an average width of 100 nm and a few micrometers in length. The photoluminescent properties of these structures were also investigated where it shows strong blue-green emission at room temperature for the samples doped with tin.

Sol–gel synthesis of novel cobalt doped zinc tin oxide composite for photocatalytic application

A novel photocatalyst based on cobalt doped zinc tin oxide is proposed. Cobalt doped zinc tin oxide thin films were deposited using a sol–gel deposition method and characterized by scanning electron microscopy (SEM), X-ray diffraction, Raman spectroscopy, photoluminescence emission measurement and UV–vis spectroscopy. It was found that the addition of Co into the zinc tin oxide does influence the structural and optical properties of the thin films and increases the overall photocatalytic degradation of methylene blue.

Optical and electrical properties of Mg-doped zinc tin oxide films prepared by radio frequency magnetron sputtering

In this study, magnesium (Mg)-doped zinc tin oxide (ZTO) films were deposited by radio frequency (RF) magnetron sputtering. The Mg was selected as an electron suppressor for the ZTO films. X-ray diffraction (XRD) was carried out to observe the crystallinity of the films. The Mg-doping effects on the elemental properties of the films were investigated by X-ray photoelectron spectroscopy (XPS). The optical properties, such as transmittance, optical band gap, Urbach energy, and refractive index, were compared as a function of Mg content. Bottom-gate transparent thin-film transistors (TTFTs) were fabricated on N+ Si wafers. The turn-off voltage, threshold voltage, and mobility variation as a function of Mg content were studied.

Synthesis of tin-doped zinc oxide microrods for gas sensor application

Sn-doped ZnO microrods have been fabricated via the vapor-phase transport method. The as-synthsized samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The gas sensors based on the Sn-doped ZnO microrods are very sensitive to ethanol gas, and the sensitivity is about 52.4 against 100ppm ethanol at working temperature of 300°C. The synthesized microrods have high surface-to-volume ratio and large quantity of oxygen vacancy which might be the origin of the high sensitivity for ethanol gas. The results suggest that the Sn-doped ZnO microrods are good candidates for fabricating effective and high performance gas sensors.

Simple Aqueous Solution Route for Fabrication High Performance Oxide TFT

Metal oxide semiconductor attracts considerable attentions for driving circuit of next generation displays and energy devices owing to their simultaneous transparency and high electrical performance. We report fluorine doped zinc tin oxide (ZTO:F) and indium zinc oxide (IZO) thin-film transistors (TFT) via aqueous route. The aqueous route enables the fabrication of oxide TFT at low temperature with reasonable cost. The ZTO:F TFT exhibits good electrical performance and stability over electrical stress due to the effective removal of oxygen vacancy and generation of carrier by F doping. The IZO TFTs also shows good performance in terms of mobility and operation accuracy. Finally, the optimized IZO TFT is fabricated on plastic substrate with 250 ℃ annealing and the device exhibits sufficient performance for operation of various displays and basic circuitries.

Zn-Doped SnO2 with 3D Cubic Structure for Humidity Sensor

Zinc doped tin oxide (Zn-doped SnO2) with three dimension (3D) cubic structure has been successfully grown on top of ZnO thin film. In this research, ZnO thin films prepared by rf magnetron sputtering and cubic structure of Zn-doped SnO2 developed by immersion method at low temperature are reported. The effects Zn doping concentration at (0 to 5 at.%) on the Zn-doped SnO2 were studied to form cubic structure. The performance of humidity sensor was tested using current-voltage (I-V) measurement (Keithley 2400) in a controlled chamber. The structural characterization was performed using field emission scanning electron microscopy (FESEM). The sensor performance at 5% doping concentration was found to be highly sensitive and can be used as humidity sensor. The size of cubic structure decreases with the increase in doping concentration.

Influence of Sn doping level on antibacterial activity and certain physical properties of ZnO films deposited using a simplified spray pyrolysis technique

Nanocrystalline tin–doped zinc oxide (ZnO:Sn) films with different Sn doping levels (0,2,4,…,10at.%) were fabricated using a simplified spray pyrolysis technique. All the deposited films were characterized in order to explore the influence of Sn doping level on antibacterial and certain physical properties. The XRD studies revealed that all the films exhibited preferential orientation along the (002) plane irrespective of the Sn doping level. The electrical sheet resistance (Rsh) sharply decreases with the increase in the Sn doping level and attain a minimum value (3.88×102Ω/□) at 6at.% and then increases for further doping. The reason for this observed variation in the Rsh value is discussed in detail. The optical studies showed that all the films exhibited good transparency (≈85%) in the visible region. The obtained photoluminescence (PL) spectra endorsed the good crystalline quality of the films and enhancement of the optical band gap (Eg) caused by Sn doping. From the SEM images, it is inferred that the incorporation of Sn has the tendency of repairing the porous structure of ZnO films. The antibacterial activity of ZnO:Sn films was found to be enhanced with the increase in Sn incorporation into the ZnO lattice.

Influence of tin doping onto structural, morphological, optoelectronic and impedance properties of sprayed ZnO thin films

Tin doped zinc oxide thin films are synthesized by simple chemical spray pyrolysis onto glass substrates using zinc acetate and stannic chloride precursors in an aqueous medium. The influence of tin doping onto photoelectrochemical, structural, morphological, optical, electrical and impedance properties have been investigated. Structural analysis confirms the hexagonal (wurtzite) structure of deposited films with crystal reorientation effect. SEM micrographs depict the films are rough, adherent and homogeneous with varying grain size (average grain size ∼100–300nm). Contact angle measurement shows that the films are hydrophilic in nature. Valence states of constituent elements in ZnO host lattice are analyzed by X-ray photoelectron spectroscopy. Direct band gap of the films decreases with tin doping up to 3.19eV. The highest electrical conductivity (0.95Ω−1cm−1 and carrier concentration (8.94×1017cm−3) and lowest mobility (6.64cm2V−1s−1) is observed at 1.5at.% tin doping. We studied interparticle interactions like grains, grain boundary effects using complex impedance spectroscopy.

Study on the doping effect of Sn-doped ZnO thin films

Tin doped zinc oxide (ZnO:Sn) thin films were deposited onto Pyrex glass substrates by chemical spray pyrolysis technique starting from zinc acetate (CH3CO2)2Zn⋅2H2O and tin chloride SnCl2. The effect of Sn doping on structural, optical and electrical properties was investigated. The atomic percentages of dopant in ZnO-based solution were y=[Sn4+]/[Zn2+]=0%, 0.2%, 0.6% and 1%. It was found that all the thin films have a preferential c-axis orientation. With increase of Sn doping, the peak position of the (002) plane was shifted to the high 2θ values. ZnO:Sn demonstrated obviously improved surface roughness, reduced average crystallite size, enhanced Hall mobility and reduced resistivity. Among all of the tin doped zinc oxide in this study, films doped with 0.6at.% Sn concentration exhibited the best properties, namely a Hall mobility of 9.22cm2V−1s−1, an RMS roughness of 37.15nm and a resistivity of 8.32×10−2Ωcm.

Ag Doped Zinc Tin Oxide as Cathode for Organic Photovoltaic Cells

A thin Ag layer embedded between layers of zinc tin oxide (ZTO) are compared to cells using an indium tin oxide electrode was investigated for inverted organic bulk heterojunction solar cells employing a multilayer electrode. ZTO/Ag/ ZTO (ZAZ) electrode is the preparation at room temperature, a high transparency in the visible part of the spectrum, and a very low sheet resistance comparable to treated ITO without the need for any thermal post deposition treatment as it is necessary for ITO. The In-free ZAZ electrodes exhibit a favorable work function of 4.3 eV and are shown to allow for excellent electron extraction even without a further interlayer. This renders ZAZ a perfectly suited bottom electrode for inverted organic solar cells with simplified cell architecture.

Synthesis and Characterization of Ultrathin Tin‐Doped Zinc Oxide Nanowires (Eur. J. Inorg. Chem. 27/2012)

The cover picture shows the synthesis of ultrathin tin-doped zinc oxide nanowires by employing an aminolysis approach. The molecular mechanism of the reactions was identified by Fourier transform infrared (FTIR) spectroscopy. This finding suggests that the introduction of group IV dopants may serve as an effective strategy to control the shape of doped ZnO nanocrystals. Details are discussed in the Short Communication by Y. Jin et al. on p. 4268 ff.

Synthesis and Characterization of Ultrathin Tin‐Doped Zinc Oxide Nanowires

Ultrathin tin-doped zinc oxide (Sn-doped ZnO) nanowires with uniform diameters of 2.3 ± 0.2 nm were synthesized by means of a facile colloidal method employing an aminolysis approach. This finding suggests that the introduction of group IV dopants may serve as an effective strategy to control the shape of doped ZnO nanocrystals. This doping procedure may be extended to the synthesis of other doped oxide nanocrystals.

Fabrication of tin-doped zinc oxide by parallel flow co-precipitation with enhanced photocatalytic performance

Sn-doped ZnO photocatalysts with different molar ratios of Sn/Zn (1%, 2% and 3%) were prepared by a parallel flow precipitation. The photocatalysts fabricated were characterized by BET surface area, X-ray diffraction, scanning electron microscope, UV/Vis diffuse reflectance spectroscopy and surface photovoltage spectroscopy, respectively. The results showed that doping ZnO with Sn increased BET surface area of ZnO. The XRD patterns of Sn-doped ZnO photocatalysts calcined at 573K showed only the characteristic peaks of wurtzite-type. Doping ZnO with Sn changed the morphology of ZnO, the morphology changed from irregular lump and particle to irregular honeycomb. The photoinduced charge separation rate of 1% Sn doped-ZnO was higher than that of ZnO, while 2% and 3% Sn doped-ZnO had lower photovoltage than that of ZnO. The photocatalytic activity of Sn-doped ZnO photocatalysts for decolorization of methyl orange solution was evaluated, of all photocatalysts prepared, Sn-doped ZnO with 1% Sn exhibited the best photocatalytic activity and the underlying reason was discussed.

Effect of doping concentration on the structural and optical properties of pure and tin doped zinc oxide thin films by nebulizer spray pyrolysis (NSP) technique

Pure and tin doped zinc oxide (Sn:ZnO) thin films were prepared for the first time by NSP technique using aqueous solutions of zinc acetate dehydrate, tin (IV) chloride fendahydrate and methanol. X-ray diffraction patterns confirm that the films are polycrystalline in nature exhibiting hexagonal wurtzite type, with (002) as preferred orientation. The structural parameters such as lattice constant (‘a’ and ‘c’), crystallite size, dislocation density, micro strain, stress and texture coefficient were calculated from X-ray diffraction studies. Surface morphology was found to be modified with increasing Sn doping concentration. The ZnO films have high transmittance 85% in the visible region, and the transmittance is found to be decreased with the increase of Sn doping concentration. The corresponding optical band gap decreases from 3.25 to 3.08eV. Room temperature photoluminescence reveals the sharp emission of strong UV peak at 400nm (3.10eV) and a strong sharp green luminescence at 528nm (2.34eV) in the Sn doped ZnO films. The electrical resistivity is found to be 106Ω-cm at higher temperature and 105Ω-cm at lower temperature.