Tin Oxide Nanowires Research Articles

Fabrication and Performances of Different Nano-Electrode Materials on Diamond Thin Film

Diamond/Al doped ZnO (AZO) nanowire composite films and diamond/indium tin oxide (ITO) nanowire composite films were separately grown on silicon substrates by using plasma chemical vapor deposition techniques and vacuum electron beam evaporation techniques. And the structures and morphologies of the as-deposited thin films were characterized by means of energy diffraction spectrum (EDS), X-ray diffraction spectrum (XRD), field emission scanning electron microscope (FE-SEM) and surface resistance tester. The experimental results indicate that AZO nanowires films and ITO nanowires films are made on the diamond substrates, respectively. The crystallinity of AZO films and ITO films is both fairly high, and the diameters of nanowires are both uniform. The average diameters of the nanowires is about 30nm of AZO and 50nm of ITO. And the corresponding film resistivity was 8.0×10-4Ω·cm and 2.0×10-4Ω·cm respectively. The feature of AZO nanowire and ITO nanowire grew on diamond films, which act as nano-electrodes, played an important role in further improving the surface resistance performances of diamond.

Broadband perfect infrared absorption by tuning epsilon-near-zero and epsilon-near-pole resonances of multilayer ITO nanowires.

We numerically investigate the broadband perfect infrared absorption by tuning epsilon-near-zero (ENZ) and epsilon-near-pole (ENP) resonances of multilayer indium tin oxide nanowires (ITO NWs). The monolayer ITO NWs array shows intensive absorption at ENZ and ENP wavelengths for p polarization, while only at the ENP wavelength for s polarization. Moreover, the ENP resonances are almost omnidirectional and the ENZ resonances are angularly dependent. Therefore, the absorption bandwidth is broader for p polarization than that for s polarization when polarized waves are incident obliquely. The ENZ resonances can be tuned by altering the doping concentration and volume filling factor of ITO NWs. However, the ENP resonances only can be tuned by changing the doping concentration of ITO NWs, and volume filling factor impacts little on the ENP resonances. Based on the strong absorption properties of each layer at their own ENP and ENZ resonances, the tuned absorption of the bilayer ITO NWs with the different doping concentrations can be broader and stronger. Furthermore, multilayer ITO NWs can achieve broadband perfect absorption by controlling the doping concentration, volume filling factor, and length of the NWs in each layer. This study has the potential to apply to applications requiring efficient absorption and energy conversion.

Properties of a single SnO2:Zn2SnO4 – Functionalized nanowire based nanosensor

Tin oxide nanowires (SnO2 NWs) exhibit large potential for applications in sensor and detector technology. Using a flame transport synthesis method, high-quality single crystalline SnO2 nanowires (NWs) with Zn2SnO4 dots functionalized surface were synthesized on a large scale. The individual SnO2:Zn2SnO4 nanowire based ultraviolet photodetector and ethanol vapors nanosensors were fabricated by contacting an individual nanowire to pre-patterned Au electrodes via a FIB/SEM system. The photodetector structure exhibited excellent photoconductive performance in terms of high response to the 375nm ultraviolet light irradiation, ultra-fast response and recovery time at different temperatures (25–300K). It also showed a long term stability and reliability. The n-type semiconducting behavior of the SnO2:Zn2SnO4, forms an excellent material for fabricating highly sensitive and rapid responding sensors, which will enable the development of high-performance multi-functional devices.

Low-Frequency Noise in High-Mobility a-InGaZnO/InSnO Nanowire Composite Thin-Film Transistors

In this letter, high-performance amorphous indium–gallium–zinc-oxide (a-InGaZnO) and indium–tin-oxide (ITO) nanowire (NW) composite thin-film transistors (TFTs) are fabricated via a sol–gel approach. By incorporating 0.5 wt% ITO NWs into the a-InGaZnO thin film, the composite TFTs can achieve an enhanced field-effect mobility of 76.5 cm2/ $\text{V}\cdot \text{s}$ and a high current density of $73.3~\mu \text{A}/\mu \text{m}$ with 10- $\mu \text{m}$ channel length. The low-frequency noise (LFN) characteristic of the composite TFTs fits the classical 1/ ${f}$ noise model very well in the frequency range 1 to 1000 Hz. The subthreshold slope and LFN results provide an alternative explanation to the enhanced performance of the composite TFTs due to the decreased interfacial trap density. The a-InGaZnO/ITO NW composite TFTs are one of the promising candidates for the development of high-speed low-cost electronics.

Investigation of growth parameters influence on Au-catalyzed ITO nanowires by electron beam evaporation method

Indium tin oxide (ITO) nanowires (NWs) were synthesized via Gold (Au) catalyst assisted Vapor–Liquid–Solid (VLS) growth mechanism by electron beam evaporation method (EBE). Effects of growth parameters such as evaporation rate of ITO, oxygen partial pressure, and different types of substrates on the growth of ITO NWs were studied. Experimental investigations show that the Au-catalyzed VLS growth mechanism was dominating over self-catalytic VLS growth mechanism at lower evaporation rates of ITO. Self-catalytic VLS growth was dominating over Au-catalyzed VLS growth at the higher ITO evaporation rates of 6 Å/sec and above. Furthermore, change of growth mechanism was explained by considering incubation time and diameter of the catalyst particles. It was observed that the NWs growth enhanced at lower oxygen partial pressures and completely seized at higher oxygen partial pressure of 6×10−4 mbar and above. The complete absence of NWs growth at higher oxygen partial was explained by considering the growth rates of VLS and VS deposition. It was found that, the ITO NWs growth is independent of type of the substrate used. Understanding the growth mechanism transition and growth behaviour with deposition parameters are novel findings for the present report. In addition to the above, optical and electrical properties of ITO NW films were also studied. These ITO NWs films will be useful in antireflection, transparent conducting oxide coating applications. Moreover, these ITO NWs films may improve the performance of the various optoelectronic devices.

The Joule heating problem in silver nanowire transparent electrodes

Silver nanowire transparent electrodes have shown considerable potential to replace conventional transparent conductive materials. However, in this report we show that Joule heating is a unique and serious problem with these electrodes. When conducting current densities encountered in organic solar cells, the average surface temperature of indium tin oxide (ITO) and silver nanowire electrodes, both with sheet resistances of 60 ohms/square, remains below 35 °C. However, in contrast to ITO, the temperature in the nanowire electrode is very non-uniform, with some localized points reaching temperatures above 250 °C. These hotspots accelerate nanowire degradation, leading to electrode failure after 5 days of continuous current flow. We show that graphene, a commonly used passivation layer for these electrodes, slows nanowire degradation and creates a more uniform surface temperature under current flow. However, the graphene does not prevent Joule heating in the nanowires and local points of high temperature ultimately shift the failure mechanism from nanowire degradation to melting of the underlying plastic substrate. In this paper, surface temperature mapping, lifetime testing under current flow, post-mortem analysis, and modelling illuminate the behaviour and failure mechanisms of nanowires under extended current flow and provide guidelines for managing Joule heating.

Interplay of Nanoscale, Hybrid P3HT/ZTO Interface on Optoelectronics and Photovoltaic Cells.

Photovoltaic effects in poly(3-hexylthiophene-2,5-diyl) (P3HT) have attracted much attention recently. Here, natively p-type doped P3HT nanofibers and n-type doped zinc tin oxide (ZTO) nanowires are used for making not only field-effect transistors (FETs) but also p-n nanoscale diodes. The hybrid P3HT/ZTO p-n heterojunction shows applications in many directions, and it also facilitates the investigation of photoelectrons and photovoltaic effects on the nanoscale. As for applications, the heterojunction device shows a simultaneously high on/off ratio of n- and p-type FETs, gatable p-n junction diodes, tristate buffer devices, gatable photodetectors, and gatable solar cells. On the other hand, P3HT nanofibers are taken as a photoactive layer and the role played by the p-n heterojunction in the photoelectric and photovoltaic effects is investigated. It is found that the hybrid P3HT/ZTO p-n heterojunction assists in increasing photocurrents and enhancing photovoltaic effects. Through the controllable gating of the heterojunction, we can discuss the background mechanisms of photocurrent generation and photovoltaic energy harvesting.

Enhanced humidity sensing performance using Sn-Doped ZnO nanorod Array/SnO2 nanowire heteronetwork fabricated via two-step solution immersion

A unique heteronetwork consisting of crystalline tin-doped zinc oxide nanorod arrays and rutile tin oxide nanowires (SZO/SnO2) was fabricated for the first time using a two-step solution immersion method at a low temperature and immersion time (2h) for humidity sensing applications. The average diameter and thickness of the SZO are approximately 95 and 730nm, respectively. The diameter of the SnO2 nanowires ranges from 60nm to 120nm, and the length of the nanowire is approximately 10µm. The SZO/SnO2-based humidity sensor exhibits high stability and superior humidity sensing performance compared with the SZO-, SnO2-, and ZnO/SnO2-based sensors with a sensitivity of 67.8. Results demonstrate that the unique architecture of SZO/SnO2 heteronetwork can enhance the humidity sensing capabilities of the nanowires.

Ultrafast removal of heavy metals by tin oxide nanowires as new adsorbents in solid-phase extraction technique

In the present research, the removal of lead(II) and copper(II) from aqueous solutions is studied, using SnO2 nanowires as new adsorbent on solid-phase extraction disk and compared with pine core and buttonwood as biosorbents. Batch adsorption experiments were performed as a function of pH, adsorption time, solute concentration and adsorbent dose for biosorbents. Also, the pH, transfer rate of solution and metal concentration were selected as experimental parameters for the removal of heavy metals by SnO2 nanowires. All of the parameters were optimized by experimental design method for sorbents. The experimental equilibrium adsorption data are tested for the Langmuir and Freundlich equations. Results indicate the following order to fit the isotherms: Langmuir > Freundlich, in case of lead and copper ions. The removal of Cu(II) and Pb(II) was performed by selected sorbents in the presence of interferences ions. This led to no remarkable decrease in the removal efficiency of SnO2 nanowires. Using the SnO2 nanowires in the wastewater treatment indicated 96.8 and 85.28% removal efficiency in only 7 min for Pb(II) and Cu(II), respectively. SnO2 nanowires were found as reusable sorbent. Therefore, SnO2 nanowires have a good potential for application in environmental protection.

Hybrid Oblique-Angle Deposited ITO/Silver Nanowire Transparent Conductive Electrodes for Brighter Light Emitters

In this paper, hybrid transparent conductive electrodes (TCEs) consisting of oblique-angle deposited indium tin oxide (OAD ITO) and silver nanowires (Ag NWs) were developed forGaN-based light-emitting diodes (LEDs). The 100-nm thick OAD ITO acted as an Ohmic contact to p-GaN with negligible light absorption having optical transmittance as high as approximately 99% at 450 nm, and Ag NWs acted as a favorable current spreader with sheet resistance as low as $19.9~\Omega $ /sq. Consequently, the hybrid TCEs consisting of OAD ITO and Ag NWs yielded an optical transmittance of 93% at 450 nm, a sheet resistance of 18.9 $\Omega $ /sq, and a specific contact resistance of ${2.1} \times {10}^{-2} \Omega \cdot $ cm2. LEDs fabricated with hybrid TCEs demonstrated improved electrical properties and greater optical output powers than the reference LEDs. This was due to the combined effects of the improved optical transparency, the enhanced current spreading, and the surface roughening effect.

P-CoOx/n-SnO2 nanostructures: New highly selective materials for H2S detection

Nanostructures p-CoOx/n-SnO2 based on tin oxide nanowires have been prepared by two step CVD technique and characterized in detail by XRD, XRF, XPS, HAADF-STEM imaging and EDX-STEM mapping. Depending on the temperature of decomposition of cobalt complex during the second step of CVD synthesis of nanostructures cobalt oxide forms a coating and/or isolated nanoparticles on SnO2 nanowire surface. It was found that cobalt presents in +2 and +3 oxidation states. The measurements of gas sensor properties have been carried out during exposure to CO (14ppm), NH3 (21ppm), and H2S (2ppm) in dry air. The opposite trends were observed in the effect of cobalt oxide on the SnO2 gas sensitivity when detecting CO or NH3 in comparison to H2S. The decrease of sensor signal toward CO and NH3 was attributed to high catalytic activity of Co3O4 in oxidation of these gases. Contrary, the significant increase of sensor signal in the presence of H2S was attributed to the formation of metallic cobalt sulfide and removal of the barrier between p-CoOx and n-SnO2. This effect provides an excellent selectivity of p-CoOx/n-SnO2 nanostructures in H2S detection.

Highly patterned growth of SnO2 nanowires using a sub-atmospheric vapor–liquid–solid deposition

We report the realization of tin-oxide nanowires on patterned structures using a vapor–liquid–solid (VLS) process. While gold acts as the catalyst for the growth of wires, a tin-oxide containing sol–gel solution is spin coated on silicon substrate to act as the source for SnO vapor. The growth of tin-oxide nano-structures occurs mostly at the vicinity of the pre-deposited solution. By patterning the gold as the catalyst material, one is able to observe the growth at desired places. The growth of nanowires is highly dense within 100 µm away from such in situ source and their length is of the order of 5 µm. By further distancing from the source, the growth becomes more limited and nanowires become shorter and more sparsely distributed. The growth of nanowires has been studied using scanning and transmission electron microscopy tools while their composition has been investigated using XRD and EDS analyses. As a novel application, we have employed the grown nanowires as electron detection elements to measure the emitted electrons from electron sources. This configuration can be further used as electron detectors for scanning electron microscopes.

Electrical and optical properties of single-crystalline SnO $$_2$$ 2 nanowires: experiment and theory

The single-crystalline of tin oxide (SnO $$_2$$ ) nanowires (NWs) have been synthesized successfully via chemical vapour deposition and structurally characterized by using x-ray powder diffraction, transmission electron microscopy and high-resolution transmission electron microscopy. The optical absorption of the SnO $$_2$$ NWs were measured by spectrophotometer. Here, we also have performed first principles calculations based on density functional theory to investigate the band structure and dielectric function of this SnO $$_2$$ NWs to expose the luminescence mechanism. It is observed that the bandgap energy of the SnO $$_2$$ NWs to be 3.68 eV, exhibiting a 80 meV blue shift from that of the bulk SnO $$_2$$ . In a subsequent ab initio electronic structure calculation, the effects of defects (e.g., O and Sn vacancies) on the nature and origin of absorption are investigated for the single-crystalline system. Electronic structure calculations suggest electronic doping to be more effective to stabilize the absorption and the dielectric function results are consistent with the experimental phenomenon.

The Effect of Ar/O2 and H2O Plasma Treatment of SnO2 Nanoparticles and Nanowires on Carbon Monoxide and Benzene Detection.

As the final piece of a broader study on structure-property performance of SnO2 sensors, this study examines the performance of sensors created from tin(IV) oxide (SnO2) nanowires and nanoparticles as a function of temperature for untreated (UT) devices as well as those treated using Ar/O2 and H2O plasmas. Nanoparticle and nanowire sensors were exposed to air, carbon monoxide (CO), or benzene (C6H6) to determine sensor response (Rair/Rgas) and sensitivity (Rair/Rgas > 1 or Rgas/Rair > 1). Although both Ar/O2 and H2O plasma modification minimally increase sensor sensitivity toward CO and C6H6 under most conditions, this study explores initial plasma parameters of a wide array of plasma precursors to better understand the materials properties and gas-phase species that lead to specific sensing capabilities. In particular, certain Ar/O2 and H2O plasma treatment conditions resulted in increased sensitivity over UT nanomaterials at 25 and 50 °C, but of greatest importance is the knowledge gained from the combined materials, gas-phase, and sensor performance analysis that provide greater insight for effectively selecting future materials and modification systems to achieve optimal gas sensor performance.

Field emission from single crystalline tin oxide nanowires synthesized by thermal chemical vapor deposition

ABSTRACTIn this study, tin oxide (SnO2) nanowires were synthesized on cobalt coated silicon wafer at 850°C for 1 hour via carbo thermal reduction vapor method by using thermal chemical vapor deposition. The diameter and the length of SnO2 nanowires were approximately 120 nm and 10 μm, respectively. The SnO2 nanowires had tetragonal structure with lattice constants of a = b = 4.743 Å and c = 3.186 Å. In the results of field emission characteristics, the turn-on field was approximately 15 V/μm, which was defined as the field to produce a 1.1 × 10−7 A/cm2. The field emission from the SnO2 nanowires successfully followed the Fowler–Nordheim behavior. The average γ value of SnO2 nanowires was calculated to be about 467, assuming the work function of the SnO2.

An electrochemical and structural study of highly uniform tin oxide nanowires fabricated by a novel, scalable solvoplasma technique as anode material for sodium ion batteries

Abstract A novel solvoplasma based technique was used to fabricate highly uniform SnO 2 nanowires (NWs) for application as an anode in sodium-ion batteries (SIBs). This technique is scalable, rapid, and utilizes a rigorous cleaning process to produce very pure SnO 2 NWs with enhanced porosity; which improves sodium-ion hosting and reaction kinetics. The batch of NWs obtained from the plasma process were named the “as-made” sample and after cleaning the “pure” sample. Structural characterization showed that the as-made sample has a K + ion impurity which is absent in the pure samples. The pure samples have a higher maximum specific capacity, 400.71 mAhg −1 , and Coulombic efficiency, 85%, compared to the as-made samples which have a maximum specific capacity of 174.69 mAhg −1 and Coulombic efficiency of 74% upon cycling. A study of the electrochemical impedance spectra showed that the as-made samples have a higher interfacial and diffusion resistance than the pure samples and resistances increased after 50 cycles of cell operation for both samples due to progressive electrode degradation. Specific energy vs specific power plots were employed to analyze the performance of the system with respect to the working conditions.

FIB-tomographic studies on chemical vapor deposition grown SnO2 nanowire arrays on TiO2 (001)

Tin oxide nanowire arrays on titania (001) have been successfully fabricated by chemical vapor deposition of Sn(OtBu)4 precursor. The morphologies and structures of ordered SnO2 nanowires (NWs) were analyzed by cross-sectional SEM, HR-TEM and AFM. An FIB-tomography technique was applied in order to reconstruct a 3D presentation of ordered SnO2 nanowires. The achieved 3D analysis showed the spatial orientation and angles of ordered SnO2 NWs can be obtained in a one-shot experiment, and the distribution of Au catalysts showed the competition between 1D and 2D growth. The SnO2 nanowire arrays can be potentially used as a diameter- and surface-dependent sensing unit for the detection of gas- and bio-molecules.

Observation of a water droplet motion by using an oxide nanowire transistor covered by a nanofiber mesh

The motion, in particular the flow speed and dropping height, of a water droplet was observed using a tin oxide (SnO2) nanowire transistor with a polyurethane (PU) nanofiber mesh as a selective filter. The changes in the SnO2 nanowire transistor characteristics, particularly the threshold voltage and on-current, were due to the adsorbed water molecules that acted as electron donors on the surface of the oxide nanowire semiconducting channel. The role of the PU nanofiber mesh, allowing the passage of water vapor while blocking liquid water, was to restrict the direct contact between the water droplet and the oxide nanowire semiconducting channel and electrodes, which could cause abnormal transistor characteristics. The selective filtering properties of the PU nanofiber mesh could be controlled by changing the number of PU layers.

Steady state and time resolved optical characterization studies of Zn2SnO4 nanowires for solar cell applications

Nanowires are a promising option for sensitized solar cells, sensors, and display technology. Most of the work thus far has focused on binary oxides for these nanowires, but ternary oxides have advantages in additional control of optical and electronic properties. Here, we report on the diffuse reflectance, Low Temperature and Room Temperature Photoluminescence (PL), PL excitation spectrum, and Time Resolved PL (TRPL) of Zinc Tin Oxide (ZTO) nanowires grown by Chemical Vapor Deposition. The PL from the ZTO nanowires does not exhibit any band gap or near gap emission, and the diffuse reflectance measurement confirms that these ZTO nanowires have a direct forbidden transition. The broad PL spectrum reveals two Gaussian peaks centered at 1.86 eV (red) and 2.81 eV (blue), representing two distinct defect states or complexes. The PL spectra were further studied by the Time Resolved Emission Spectrum and intensity dependent PL and TRPL. The time resolved measurements show complex non-exponential decays at all w...

Flexible transparent memory cell: bipolar resistive switching via indium–tin oxide nanowire networks on a poly(dimethylsiloxane) substrate

This report describes the fabrication and resistive switching (RS) characteristics of a novel flexible transparent (FT) resistive random access memory (ReRAM) device with a Ag/indium–tin oxide (ITO) nanowire network/ITO capacitor deposited on a PDMS substrate. The transmittance of the device is ∼70% in the visible region, and it exhibits a stable high-resistance state (HRS) to low-resistance state (LRS) ratio (HRS/LRS ratio) in different bending states. The RS characteristics are attributed to the congregate state of oxygen vacancies at different voltages, and the difference between positive and negative bending is mainly contributed by the effect of stress on the conductive layer. The FT-ReRAM can be used as nonvolatile memory element in future flexible transparent devices.