Zinc Tin Research Articles

Porous silicon ZnO/SnO2 structures for CO2 detection

In this work, we report the CO2 sensing properties of tin oxide (SnO2) and zinc oxide (ZnO) thin films deposited onto the macro porous silicon (PS) substrates. PS was synthesized by electrochemical etching of p-type monocrystalline silicon along with the metal oxide (MO) thin film deposition using precipitation method. X-ray diffraction (XRD) confirms the presence of tetragonal and wurtzite phases of SnO2 and ZnO respectively. Scanning electron microscopy (SEM) reveals the formation of substrate porosity dependent porous metal oxide nanostructures. CO2 sensing properties of SnO2/PS and ZnO/PS were studied as a function of deposition time, gas concentration and operation temperature (up to 300 °C). Sensing response of approximately 19 was obtained with SnO2/PS, whereas, ZnO/PS reveals a relatively faster response time (∼65s). Porous silicon templates improve the gas-sensing properties of both SnO2 and ZnO films by a factor of 2 with respect to the films over cSi substrates due to increase in specific surface area. Irrespective of substrate type, the SnO2 films showed higher sensing response than ZnO films due to the association and dissociation reactions of SnO2 with adsorbed atmospheric oxygen. An increased conductivity of ZnO films synthesized with zinc carbonate precursor and subsequently their sensing response (∼4) at lower temperatures (100 °C), has been attributed to an additional interface and new nano passages created due to Zn2SiO4 formation. As compared to the c-Si substrate, the faster response time was achieved for all films using PS substrates.

Endurance improvement and resistance stabilization of transparent multilayer resistance switching devices with oxygen deficient WOx layer and heat dissipating AlN buffer layer

In this study, indium tin oxide (ITO), zinc oxide (ZnO), tungsten oxide (WOx), and aluminum nitride (AlN) were employed to fabricate and investigate four transparent resistive random access memory (ReRAMs) structures: ITO/ZnO/ITO (structure 1), ITO/WO3/ZnO/ITO (structure 2), ITO/WOx(x<3)/WO3/ZnO/ITO (structure 3), and ITO/WOx(x<3)/WO3/ZnO/AlN/ITO (structure 4). Structure 4 exhibited less variation in low-resistance states, lower operating voltages, and higher endurance compared with other structures. This phenomenon was attributed to the oxygen-deficient WOx layer in structure 4, which acted as an oxygen ion reservoir for efficient resistive changes, and the WO3 layer limited the filament rupture and formation region. Moreover, the high thermal conductivity of the AlN layer alleviated the thermally activated ion movement of the ReRAM and strengthened the high-resistance state. Structure 4 was found to be the optimal structure, with median operating voltages 1.6V for SET operations and −1.0V for RESET operations, retention of >104s at 200°C, and endurance of 104cycles with a resistance ratio of over 20. Structure 4 exhibited extremely high stability in both low- and high-resistance states during cycling. The transmittance of structure 4 was 85.49%, which is suitable for optoelectronic applications.

Electron microscopy study of an Old Russian (XII century) encolpion cross with black inlay

The phase compositions of the basic material (alloy) of a pre-Mongolian Old Russian encolpion cross found near Suzdal and its black inlay have been investigated by methods of scanning and transmission electron microscopy and energy-dispersive X-ray microanalysis. The cross material is lead–zinc–tin α-bronze, and the black is copper sulfide with lead inclusions. As a result of the corrosion, tin and copper oxides and zinc sulfides, which made the cross dark gray, were formed on its surface. It is shown that the corrosion depth is as large as 50 μm; thus, laps must be prepared to accurately determine the morphology and phase composition of the corrosion layer. Decoration with black was apparently performed by pouring with copper sulfide melt or melting a powder preliminarily placed in grooves forming an image on the surface.

High-Performance Zinc Tin Oxide Semiconductor Grown by Atmospheric-Pressure Mist-CVD and the Associated Thin-Film Transistor Properties.

Zinc tin oxide (Zn-Sn-O, or ZTO) semiconductor layers were synthesized based on solution processes, of which one type involves the conventional spin coating method and the other is grown by mist chemical vapor deposition (mist-CVD). Liquid precursor solutions are used in each case, with tin chloride and zinc chloride (1:1) as solutes in solvent mixtures of acetone and deionized water. Mist-CVD ZTO films are mostly polycrystalline, while those synthesized by spin-coating are amorphous. Thin-film transistors based on mist-CVD ZTO active layers exhibit excellent electron transport properties with a saturation mobility of 14.6 cm2/(V s), which is superior to that of their spin-coated counterparts (6.88 cm2/(V s)). X-ray photoelectron spectroscopy (XPS) analyses suggest that the mist-CVD ZTO films contain relatively small amounts of oxygen vacancies and, hence, lower free-carrier concentrations. The enhanced electron mobility of mist-CVD ZTO is therefore anticipated to be associated with the electronic band structure, which is examined by X-ray absorption near-edge structure (XANES) analyses, rather than the density of electron carriers.

Cadmium Tin Oxide and Zinc Magnesium Oxide Prepared by Hollow Cathode Sputtering for CdTe Photovoltaics

ABSTRACTThis work reports the fabrication and characterization of superstrate-type Zn1-xMgxO/CdTe heterojunction solar cells on both CdxSnyO and commercial SnO2:F transparent conducting oxides (TCOs) in which the ZMO and CTO layers are produced for the first time by hollow cathode sputtering. The sputtering is conducted in a reactive mode using metal or alloyed metal targets fitted to a custom-made linear cathode. It is notable that the CdS buffer layer conventionally employed in CdTe solar cells is entirely replaced by the ZMO window layer. The use of ZMO is found to eliminate the blue loss associated with CdS optical absorption and further results in a higher open-circuit voltage. Key parameters were found to be the conduction band offset at the ZMO/CdTe interface and the ZMO thickness. It was discovered that the ZMO exhibits intense photoluminescence even at room temperature. Most of the solar cells were fabricated in the FTO/ZMO/CdTe configuration although CTO/ZMO/CdTe solar cells were also demonstrated. The CTO was produced with an electron mobility of 46 cm2 V-1s-1 without any post-deposition annealing or treatment.

Synaptic plasticity and oscillation at zinc tin oxide/silver oxide interfaces

Short-term plasticity, long-term potentiation, and pulse interval dependent plasticity learning/memory functions have been observed in junctions between amorphous zinc-tin-oxide and silver-oxide. The same junctions exhibited current-controlled negative differential resistance and when connected in an appropriate circuit, they behaved as relaxation oscillators. These oscillators produced voltage pulses suitable for device programming. Transmission electron microscopy, energy dispersive X-ray spectroscopy, and electrical measurements suggest that the characteristics of these junctions arise from Ag+/O− electromigration across a highly resistive interface layer. With memory/learning functions and programming spikes provided in a single device structure, arrays of similar devices could be used to form transistor-free neuromorphic circuits.

Growth, structure and photoluminescence properties of SnO2-ZnO (TZO) micro cubes

Structural investigation from X-ray diffraction patterns of TZO revealed the presence of SnO2 (cassiterite), ZnO (wurtzite) and ZnSnO3 and ZnSnO4 phases. The optical absorption spectra recorded for these powders dispersed in ethanol show the nature of the composite nanopowders to be semiconducting one having an optical absorption band around 280nm. Electron microscopy confirms a change in shape and size of the particles with a change in Sn/Zn ratio. The amorphous nature increases while going from Sn/Zn ratio of 0.87 to 3.75 and cubes of size ∼ 2μm, rhombohedral and irregular shaped particles are also observed. The prepared tin zinc oxide samples (TZO) show excitation bands at 241, 287 and 351 nm and common emission bands at 448, 485, 462 and 531 nm for all excitation energies. The photoluminescence and other studies reveal the role played by composition in changing the shape.

Formation and study of the properties of finishing coatings of a circuit board with tin–zinc alloy instead of tin–lead alloy coatings

A formation technique of electroplating coatings of tin–zinc alloy (50) based on using low-toxicity lactic acid as surfactant, ligand, and buffer addition was developed. The dependences of alloy composition and cathodic yield on the alloy current and the coating quality on the concentration of tin and zinc ions in the solution, the content of lactic acid, the solution acidity (pH), the temperature, and the current cathodic density were investigated. The optimum conditions of the process carrying out were determined. The performance characteristics of obtained coatings were investigated. It was proven that the coating with this alloy meets the requirements of GOST (State Standard) 23752–79 “Circuit Boards. General Technical Specifications” and can be used for the circuit boards of products of the instrument-making industry instead of tin–lead alloy, which will make it possible to reduce the environmental risk of production, as well as increase the efficiency and maintainability of devices and systems.

Enhanced electrical properties of oxide semiconductor thin-film transistors with high conductivity thin layer insertion for the channel region

This study examined the performance and the stability of indium tin zinc oxide (ITZO) thin film transistors (TFTs) by inserting an ultra-thin indium tin oxide (ITO) layer at the active/insulator interface. The electrical properties of the double channel device (ITO thickness of 5nm) were improved in comparison with the single channel ITZO or ITO devices. The TFT characteristics of the device with an ITO thickness of less than 5nm were degraded due to the formation of an island-like morphology and the carriers scattering at the active/insulator interface. The 5 nm-thick ITO inserted ITZO TFTs (optimal condition) exhibited a superior field effect mobility (∼95cm2/V·s) compared with the ITZO-only TFTs (∼34cm2/V·s). The best characteristics of the TFT devices with double channel layer are due to the lowest surface roughness (0.14nm) and contact angle (50.1°) that result in the highest hydrophicility, and the most effective adhesion at the surface. Furthermore, the threshold voltage shifts for the ITO/ITZO double layer device decreased to 0.80 and −2.39V compared with 6.10 and −6.79V (for the ITZO only device) under positive and negative bias stress, respectively. The falling rates of EA were 0.38eV/V and 0.54eV/V for the ITZO and ITO/ITZO bi-layer devices, respectively. The faster falling rate of the double channel devices suggests that the trap density, including interface trap and semiconductor bulk trap, can be decreased by the ion insertion of a very thin ITO film into the ITZO/SiO2 reference device. These results demonstrate that the double active layer TFT can potentially be applied to the flat panel display.

Thermophysical structure-sensitive properties of Tin–Zinc alloys

Tin–zinc-based alloys are under intense consideration as alternative lead-free solders for consumer electronics and telecommunications. This is because of their excellent creep resistance and fatigue resistance as well as mechanical and tensile properties. In present work, the thermophysical structure-sensitive properties of the Sn–Zn alloys prepared in the traditional bulk form, and in the foil form (30 µm thick and 6 mm wide) by the rapid solidification technique were studied and compared. The electrical conductivity study of Sn–Zn alloys from the Sn-rich side was carried out in the solid and liquid states in a wide temperature range from the room temperature up to 900 K. Thermal conductivity and viscosity were measured in the liquid state. The thermal conductivity results are consistent with the values calculated from the electrical conductivity data according to the Wiedemann–Franz–Lorenz law. The concentration dependence of viscosity revealed a negative deviation from the additive values. The melting-solidification region was studied by XRD and DSC. The behavior of thermophysical properties of Sn–Zn melts in the concentration range close to the eutectic composition indicates the existence of the micro-regions of remaining Zn phase in the temperature range above the melting temperature. The micro-inhomogeneous structure with the short range order in the Sn–Zn alloys after melting was confirmed by the structure analysis.

Tin–Zinc oxide composite ceramics for selective CO sensing

Composite metal oxide gas sensors were intensely studied over the past years having superior performance over their individual oxide components in detecting hazardous gases. A series of pellets with variable amounts of SnO2 (0–50mol%) was prepared using wet homogenization of the component oxides leading to the composite tin-zinc ceramic system formation. The annealing temperature was set to 1100°C. The samples containing 2.5mol% SnO2 and 50mol% SnO2 were annealed also at 1300°C, in order to observe/to investigate the influence of the sintering behaviour on CO detection. The sensor materials were morphologically characterized by scanning electron microscopy (SEM). The increase in the SnO2 amount in the composite ceramic system leads to higher sample porosity and an improved sensitivity to CO. It was found that SnO2 (50mol%) - ZnO (50mol%) sample exhibits excellent sensing response, at a working temperature of 500°C, for 5ppm of CO, with a fast response time of approximately 60s and an average recovery time of 15min. Sensor selectivity was tested using cross-response to CO, methane and propane. The results indicated that the SnO2 (50mol%)-ZnO (50mol%) ceramic compound may be used for selective CO sensing applications.

Fabrication of Photovoltaic Devices Using ZnO Nanostructures and SnS Thin Films

The development of nontoxic and cost-effective solar cell devices is one of the challenging tasks even now. With this objective, solar cell devices using tin mono sulfide (SnS) thin films and zinc oxide (ZnO) nanostructures with a superstrate configuration of ITO/ZnO film/ZnO nanorods/SnS film/Zn have been fabricated and their photovoltaic properties have been investigated. Vertically aligned ZnO nanostructures were grown on indium doped tin oxide substrate by chemical solution method and then, SnS thin films were deposited by thermal evaporation method. A typical solar cell device exhibited significant light conversion efficiency with an open circuit voltage and short circuit current of 350[Formula: see text]mV and 5.14[Formula: see text]mA, respectively.

A Comparative Wet Chemical Synthesis of Zinc Oxide and Tin Oxide Nanoparticles: Structural and Optical Properties

A Comparative Wet Chemical Synthesis of Zinc Oxide and Tin Oxide Nanoparticles: Structural and Optical Properties

Phosphonic Acids for Interfacial Engineering of Transparent Conductive Oxides.

Transparent conducting oxides (TCOs), such as indium tin oxide and zinc oxide, play an important role as electrode materials in organic-semiconductor devices. The properties of the inorganic-organic interface-the offset between the TCO Fermi level and the relevant transport level, the extent to which the organic semiconductor can wet the oxide surface, and the influence of the surface on semiconductor morphology-significantly affect device performance. This review surveys the literature on TCO modification with phosphonic acids (PAs), which has increasingly been used to engineer these interfacial properties. The first part outlines the relevance of TCO surface modification to organic electronics, surveys methods for the synthesis of PAs, discusses the modes by which they can bind to TCO surfaces, and compares PAs to alternative organic surface modifiers. The next section discusses methods of PA monolayer deposition, the kinetics of monolayer formation, and structural evidence regarding molecular orientation on TCOs. The next sections discuss TCO work-function modification using PAs, tuning of TCO surface energy using PAs, and initiation of polymerizations from TCO-tethered PAs. Finally, studies that examine the use of PA-modified TCOs in organic light-emitting diodes and organic photovoltaics are compared.

A new method of preparing highly conductive ultra-thin indium tin oxide for plasmonic-enhanced thin film solar photovoltaic devices

Recent numerical modeling of plasmonic metallic nanostructures have shown great potential as a method of light management in thin-film nanodisc-patterned hydrogenated amorphous silicon (a-Si:H) solar photovoltaic (PV) cells. A significant design challenge for such plasmonic-enhanced PV devices is the requirement for ultra-thin transparent conducting oxides (TCOs) with high transmittance (low loss) and low enough resistivity to be used as device top contacts/electrodes. Most work on TCOs is on relatively thick layers and the few reported cases of thin TCO showed a marked decrease in conductivity. Recent work on ultra-thin TCOs of aluminum-doped zinc oxide, indium-doped tin oxide and zinc oxide revealed an unavoidable trade-off between transmittance and resistivity when fabricated with conventional growth methods. Ultra-thin films showed a tendency to be either amorphous and continuous or form as isolated islands. This results in poor electrical properties, which cannot be improved with annealing as the delicate thin films nucleate to form grain clusters. In order to overcome this challenge, this study investigates a novel method of producing ultra-thin (<40nm) high quality TCOs. First, ~80nm ITO films are sputtered in various argon–oxygen atmospheres and annealed to increase conductivity. The most promising materials were then reduced in thickness with a controlled low-cost room-temperature cyclic wet chemical etching process to reach the desired thickness. The degradation in the electrical conductivity was tracked as a function of thickness. The sheet resistance of 36nm thin films was observed to be of the same order compared to the much thicker commercial ITO films currently used as transparent electrodes in PV and other opto-electronic devices. Experimental optical properties of the shaved films were then used in an optimized model of nano-disc plasmonic a-Si:H solar cells. Simulations indicate that optical enhancement greater than 21% are possible in the 300–730nm wavelength range, when compared to the reference cell. Using the novel chemical shaving method described here, high-quality ultra-thin ITO films capable of improving the efficiency of thin film a-Si:H solar cells have been demonstrated. The methods employed in the optimization process are well established and economically viable, which provide the technical potential for commercialization of plasmonic based solar cells.

Gas Sensing Studies of an n-n Hetero-Junction Array Based on SnO2 and ZnO Composites

A composite metal oxide semiconductor (MOS) sensor array based on tin dioxide (SNO2) and zinc oxide (ZnO) has been fabricated using a straight forward mechanical mixing method. The array was characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, Raman spectroscopy and X-ray diffraction. The array was evaluated against a number of environmentally important reducing and oxidizing gases across a range of operating temperatures (300–500 °C). The highest response achieved was against 100 ppm ethanol by the 50 wt% ZnO–50 wt% SnO2 device, which exhibited a response of 109.1, a 4.5-fold increase with respect to the pure SnO2 counterpart (which displayed a response of 24.4) and a 12.3-fold enhancement with respect to the pure ZnO counterpart (which was associated with a response of 8.9), towards the same concentration of the analyte. Cross sensitivity studies were also carried out against a variety of reducing gases at an operating temperature of 300 °C. The sensors array showed selectivity towards ethanol. The enhanced behaviour of the mixed oxide materials was influenced by junction effects, composition, the packing structure and the device microstructure. The results show that it is possible to tune the sensitivity and selectivity of a composite sensor, through a simple change in the composition of the composite.

Effect of Zn:Sn Ratio and Calcination Temperature on Phase Transformation of Zn-Sn-O Compound

Zn-Sn-O powders were synthesized by simple co-precipitation method combined with calcination process using zinc chloride (ZnCl2) and tin (IV) chloride pentrahydrate (SnCl4–5H2O) as starting precursors of Zn and Sn in aqueous solution. The effect of precursors ratio on phase structure of Zn-Sn-O compound was investigated by varying ratio of Zn:Sn in the co-precipitation system. For the effect of calcination temperature, the as-precipitated product obtained at Zn:Sn ratio of 1:1 was calcined at different temperatures (400-900 °C) to study phase transformation. Structural properties of as-precipitated and after-calcined powders were characterized by X-ray diffraction (XRD) while surface morphologies of final products were observed by scanning electron microscope (SEM), and thermogravimetric analysis (TGA) was used to study their thermal properties. The results indicate that the XRD pattern of Zn-Sn-O powders obtained at ratio of Zn greater than Sn can be assigned to mixed phase of ZnO and Zn2SnO4. On the other hand the XRD patterns of products obtained at ratio of Sn greater than Zn confirm a mixture of SnO2 and Zn2SnO4. For the effect of calcination temperature, the rarely spinel phase of Zn2SnO4 begin occur with mixed phase of ZnO and SnO2 at the calcination temperature of 600 °C and pure spinel structure can be obtained at the temperature above 900 °C.

Biological synthesis of nano composite SnO2- ZnO – Screening for efficient photocatalytic degradation and antimicrobial activity

Coupled semiconductor oxides in the nano scale are in greater demand due to their wide spectrum of applications. The present study deals with the simple eco-friendly Sol – Gel synthesis of the nano composite of tin (IV) oxide and zinc oxide (SnO2 – ZnO) using the gel of aloe vera plant as the medium from the precursors of Sn(II) chloride and Zinc acetate respectively. The results of the Powder X-ray Diffractograms, Scanning Microscopic images indicated the decisive role of the plant gel in the aqueous solubility, crystallite size reduction and spherical morphology of the synthesized nano composite. Preliminary application study indicated the efficiency of the sample in the visible light assisted degradation of the organic dye, Methyl orange. Also, the nano composite was found to be effective against the growth of staphylococcus aureus and E. Coli at the microgram level. Ultimately the study widened the scope of the multi functionality of the nano metric composite of tin (IV) oxide with Zinc oxide.

Effect of copper content and sulfurization process on optical, structural and electrical properties of ultrasonic spray pyrolysed Cu2ZnSnS4 thin films

This paper reports the effect of copper content and of the sulfurization process (using elemental sulfur vapor) on the growth, structure, elemental composition, and on the optical and electrical properties of Cu2ZnSnS4 (CZTS) thin films deposited on glass substrates using ultrasonic Spray Pyrolysis. For this purpose, a series of aqueous solutions consisting of copper (II) and tin (IV) chlorides, zinc (II) acetate and thiourea with different copper concentrations (x = Cu/(Zn + Sn) = 0.8, 1, 1.2 and 1.4 while Zn/Sn = 1) were prepared. X-ray diffraction, raman spectroscopy, scanning electronic microscopy, atomic force microscopy, energy dispersive X-ray spectroscopy, ultraviolet–visible–near infrared absorbance spectroscopy and sheet resistance analyses were used to follow the evolution of the investigated properties. The results outlined a Kesterite type CZTS phase and a secondary copper sulfide (Cu2-xS) phase, and their ratio strongly depends on the copper salt concentration and heat-treatment atmosphere. No traces of secondary phases of zinc or tin sulfides are found while high purity CZTS was obtained with the post-sulfurized film at x = 1.2. It was found that the application of additional sulfurization enhances the grain growth to reach 300 nm in size and induces significant improvement of both CZTS crystallinity and electrical conductivity. The optical band gap ranges between 1.44 and 1.57 eV depending on the composition and the sulfur deficiency is strongly reduced leading to Cu-poorer and Zn-richer compounds, as compared to those annealed in nitrogen atmosphere.This study shows promising results, as a first step in developing photovoltaic applications, using sprayed CZTS as absorber.

Ammonia detection of one-dimensional nano-structured polypyrrole/metal oxide nanocomposites sensors

The nanocomposites based on polypyrrole (PPy) nanostructures containing tin dioxide (SnO2) or zinc oxide (ZnO) nanoparticles were prepared and studied via different methods such as Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), ultraviolet-visible (UV–vis) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The ammonia sensing performances of one-dimensional (1-D) nano-structured polypyrrole and its nanocomposites with metal oxides were investigated and the effect of nanofiller type on the sensors behaviour was studied. The PPy and its nanocomposites with metal oxides exhibited high selectivity for ammonia with respect to methanol and ethanol vapors. The response of the sensor based on PPy/ZnO nanocomposite was found to be much pronounced and more retainable than that of PPy and PPy/SnO2 when exposed to ammonia. The cyclability and linearity of the response for this sensor in presence of ammonia vapor has been investigated as well, suggesting a great potential in detection of ammonia for the prepared sensor.