ITO Nanorods Research Articles

Electrical properties and field emission characteristics of ITO nanorod thin films synthesized by electron beam physical vapor deposition

Electrical properties and field emission characteristics of ITO nanorod thin films synthesized by electron beam physical vapor deposition

Simulation and Analysis of Infrared Extinction Characteristics of ITO Nanorod Structures

Simulation and Analysis of Infrared Extinction Characteristics of ITO Nanorod Structures

3-5 µm mid-infrared broadband absorbers composed of layered ITO nanorod arrays with high visible light transmittance.

A mid-infrared broadband absorber with high visible light transmittance is proposed in this paper. The absorber is composed of layered ITO nanorod arrays with increasing angles fabricated by oblique angle deposition technique. The experimental results show that the average transmittance of the absorber reaches 80% in the 400-800 nm band and the integrated absorption reaches 82.9% in the 3-5 µm band, when the QCM thickness of the first layer of film is 100 nm and the deposition angle θ is 10°, the QCM heights of the second to fifth layers of nanorods are all 330 nm, and their deposition angles are 55°, 68°, 80°, and 87°, respectively. The high transmittance in the visible band is attributed to the gradient of the refractive index. The broadband absorption in the mid-infrared band results from different resonances in the empty cavities with different sizes. Such a simple and large-area absorber has potential applications in window materials and infrared cloaking.

Characterization broadband omnidirectional antireflection ITO nanorod films coating

Three-dimensional (3D) nanostructure electrode based on the transparent conductive oxide (TCO) is an alternative and effective approach for increasing the performance of next-generation photovoltaic and optoelectronic devices. In this work, we prepared the vertically aligned indium tin oxide nanorods (ITO-NRs) film on silicon (100) wafer and commercial ITO thin-film coated glass substrate (ITO-TF/glass) by the glancing angle deposition (GLAD) technique. The morphologies of the ITO-NRs films were confirmed by field-emission scanning electron microscope (FE-SEM). The grazing-incident X-ray diffraction (GIXRD) observed that the ITO-NRs were formed as amorphous and nanocrystalline phase. The photoemission spectra revealed the atomic percentage of elements in ITO-NRs, and the work function of the ITO-NRs was found to increase as a function of layer thickness. To simply demonstrate their feasibility in TCO applications, the ITO-NRs films were deposited on ITO-TF/glass. We found that the resistivity of ITO-NRs on ITO-TF/glass was higher than that of a bare ITO-TF/glass substrate, which can explain through the surface recombination loss. Besides, by precisely tunning the layer thickness of ITO-NRs films, the optical transmittance was enhanced at 85.5–90.0% over the broad wavelength in the visible region with omnidirectional AR characteristic which is superior to that in conventional ITO-TF/glass. Our thickness dependence of the ITO-NRs properties discloses promising 3D TCO nanostructure in wide application.

Disordered and Densely Packed ITO Nanorods as an Excellent Lithography-Free Optical Solar Reflector Metasurface

Precise control and stabilization of the operating temperature environment of spacecraft and satellites during their life cycle is of paramount importance to increase device reliabilities and reduce the thermomechanical constraints. Optical solar reflectors are the physical interface between the spacecraft and space, and they are broadband mirrors for the solar spectrum, while having strong thermal emission in the mid-infrared part of the electromagnetic spectrum. Strong light–matter interactions in metamaterials and metasurfaces offer significant advantages compared to the conventional methods in performance, weight, launch, and assembly costs. However, the fabrication complexity of these metastructures due to necessitating lithography hinders their upscaling, reproducibility, large-area compatibility, and mass production. In this regard, we propose a facile, lithography-free fabrication route, exploiting oblique deposition to design a metasurface based on disordered and densely packed Indium Tin Oxide (...

Comparing different ITO-metal thin film structures for ethanol and carbon dioxide sensing application

PurposeIndium tin oxide (ITO) thin film as a gas sensor has a good stability and performance. The purpose of this paper is to compare the effect of depositing different metal layers in various structures on the gas sensing properties of ITO toward ethanol and carbon dioxide.Design/methodology/approachIn this work, the authors have investigated the effect of depositing an ITO layer by Electron Beam Evaporation technique under, on top and in the middle of the metal layers. Surface morphology and the response of the fabricated sensors were compared and the changes in the response of the sensors to ethanol and carbon dioxide gases were studied at various gas concentrations and operating temperatures. The sensing mechanism and result of the other studies were also discussed.FindingsComparing various sensor structures reported in this study showed that the ITO nanorods which grow over distinct Ag nano-islands in the ITO/Ag structure has the highest response of 420 per cent to ethanol which is 6 times more than the single-layer ITO sensor. Further, gold nanoparticles on ITO nanorods in Au/ITO/Ag structure produce a very complex structure that exhibits the best response of 150 per cent to carbon dioxide which is 6.5 times more than the single-layer ITO sensor. The response and the recovery times were improved also.Originality/valueDifferent ITO-metal gas sensor structures were studied and compared toward ethanol and carbon dioxide. Response enhancement and various surface changes through a series of experiments and analysis were discussed and compared to the literature.

Enhanced transmission based on vertically aligned ITO NRs deposited by Ion assisted electron beam evaporation with glancing angle deposition technique

In this study, we investigated the effects on the film thickness of the vertically aligned indium-doped tin oxide nanorods (ITO NRs). The ITO nanorods of deposited time at 180 to 780 sec were deposited on the silicon wafers and ITO-coated glass substrate by the ion-assisted electron-beam evaporation with the glancing-angle deposition technique. The physical microstructures and optical properties of the prepared samples have been investigated by grazing-incident X-ray diffraction (GIXRD), field-emission scanning electron microscopy (FE-SEM), and spectrophotometry. From the results, the ITO nanorods indicated the bixbite structures. The FE-SEM micrographs showed the changes of the physical morphologies based on the increased film thickness. The angle-dependent transmission as measured from -80° to 80° incident angles demonstrated the increased optical transmission from the vertically aligned ITO nanorods, compared to that of the ITO-coated glass. The enhancement of the optical transmission was related to the anti-reflection and light-scattering properties of the ITO nanorods, and offered a great potential for solar cell applications.

Large optical nonlinearity of ITO nanorods for sub-picosecond all-optical modulation of the full-visible spectrum.

Nonlinear optical responses of materials play a vital role for the development of active nanophotonic and plasmonic devices. Optical nonlinearity induced by intense optical excitation of mobile electrons in metallic nanostructures can provide large-amplitude, dynamic tuning of their electromagnetic response, which is potentially useful for all-optical processing of information and dynamic beam control. Here we report on the sub-picosecond optical nonlinearity of indium tin oxide nanorod arrays (ITO-NRAs) following intraband, on-plasmon-resonance optical pumping, which enables modulation of the full-visible spectrum with large absolute change of transmission, favourable spectral tunability and beam-steering capability. Furthermore, we observe a transient response in the microsecond regime associated with slow lattice cooling, which arises from the large aspect-ratio and low thermal conductivity of ITO-NRAs. Our results demonstrate that all-optical control of light can be achieved by using heavily doped wide-bandgap semiconductors in their transparent regime with speed faster than that of noble metals.

Scaling the Artificial Polariton Bandgap at Infrared Frequencies Using Indium Tin Oxide Nanorod Arrays

Artificial polariton bandgaps at infrared frequencies are investigated by exploiting the strong coupling of electromagnetic waves with induced electric dipoles in two‐dimensional (2D) indium tin oxide nanorod arrays (ITO‐NRAs). The electric dipoles originate from the collective oscillations of free electrons within the individual ITO nanorods undergoing plasmonic resonance. Controlling the near‐field interactions among the neighboring electric dipoles allows for manipulation of the collective polariton modes that are manifested as a polariton bandgap. A theoretical model is developed to understand the coupled phenomena underlying the unique characteristics of plasmon–polariton bandgaps. With high‐degree geometric control of the ITO‐NRAs, it is experimentally demonstrated that reducing the spacing between ITO nanorods in a square array strengthens the near‐field interactions and thus results in a redshift as well as broadening of the polariton bandgap. Furthermore, arranging ITO‐NRAs in a rectangular lattice breaks the symmetry with respect to the principle axis, which leads to a splitting of the collective polariton modes owing to the competition between the quasi‐longitudinally and quasi‐transversely coupled plasmon–polariton modes. The work highlights the use of a classical dipole coupling method for scaling polariton bandgaps to the infrared in artificial plasmonic lattices, thereby offering a new design dimension for infrared sensing, absorbers, and optical communications.

Performance improvement mechanisms of bias-assisted photoelectrochemical treated GaSb-based solar cells with ITO nanorod array

Performance improvement mechanisms of bias-assisted photoelectrochemical treated GaSb-based solar cells with ITO nanorod array

Highly sensitive double-layered nanorod array gas sensors prepared by oblique angle deposition

ITO based nanorod arrays fabricated by oblique angle deposition (OAD) were designed as resistive gas sensors for NO2 detection, and the detection limit was found to reach as low as 50 ppb with a response time of 20 min. A comparative study shows that the ITO nanorod array has a higher sensing response than that of the ITO film, and a double-layered ITO nanorod array design could further improve the sensing response. By increasing the vapor incident angle during the nanorod fabrication, the sensing response also increases, due to the increased porosity and gas penetration. It is expected that OAD technique could become a versatile and scalable fabrication technique for gas sensors.

The Effect of the Oxygen Plasma Treatment for ITO and ZnO Nanorods on the Electroluminescence of ZnO Nanorod/MEH-PPV Heterostructure Devices

Series devices of ITO/ZnO/ZnO nanorods/MEH-PPV/Al have been fabricated. ITO and ZnO nanorods of some devices are treated by O2 plasma. The electroluminescence of different devices is detected under different biases. UV electroluminescence of ZnO nanorods at 380nm is observed in all the devices. The intensity of 380nm increases when both ITO and ZnO nanorods are treated. The turn-on voltage of the treated device is lower than that of the non-treated device, and the EL power is enhanced. When the thickness of MEH-PPV is sufficiently thin, only 380 nm electroluminescence, besides a weak defect emission at 760 nm, is detected. The enhancement mechanism of the electroluminescence of the treated devices is discussed.

Studies on the optoelectronic properties of the thermally evaporated tin-doped indium oxide nanostructures

Indium oxide (In2O3) nanorods, nanotowers and tin-doped (Sn:In=1:100) indium oxide (ITO) nanorods have been fabricated by thermal evaporation. The morphology, microstructure and chemical composition of these three nanoproducts are characterized by FE-SEM, HRTEM and XPS. To further investigate the optoelectronic properties, the I–V curves and cathodoluminescence (CL) spectra are measured. The electrical resistivity of In2O3 nanorods, nanotowers and ITO nanorods are 1.32kΩ, 0.65kΩ and 0.063kΩ, respectively. CL spectra of these three nanoproducts clearly indicate that tin-doped (Sn:In=1:100) indium oxide (ITO) nanorods cause a blue shift. No doubt ITO nanorods obtain the highest performance among these three nanoproducts, and this also means that Sn-doped In2O3 nanostructures would be the best way to enhance the optoelectronic properties. Additionally, the growing mechanism and the optoelectronic properties of these three nanostructures are discussed. This study is beneficial to the applications of In2O3 nanorods, nanotowers and ITO nanorods in optoelectronic nanodevices.

Fabrication and characterization of large-scale multifunctional transparent ITO nanorod films

In this study, large-scale multifunctional transparent ITO nanorod films that exhibit extreme wetting states (superhydrophobicity or superhydrophilicity), high transmittance, low resistivity to infer antistatic properties, antifogging, and self-cleaning were fabricated on 2-in. glass wafers and various substrates (glass, Si, Sus of 2.5 × 2.5 cm) via radio frequency (RF)-magnetron sputtering deposition. An ITO nanorod film prepared for 60 min at 500 °C exhibited excellent optical (∼85% transmittance at 500 nm) and electrical (sheet resistance of ∼90 Ω □−1, antistatic property, with a figure of merit of 2.2 × 10−3 Ω−1) properties. It also showed superhydrophilic property (with a water contact angle as low as 1°) and antifogging. After coating with fluoroalkylsilane, the ITO nanorod film exhibited strong and stable superhydrophobic characteristics, having a high water contact angle (172.1°), a near-zero sliding angle, and self-cleaning capabilities. It is expected that large-scale multifunctional transparent ITO nanorods will lead to further technological advancements in the area of novel optoelectrical applications and in future industrial applications.

Hydrothermal preparation and optical properties of orientation-controlled WO3nanorod arrays on ITO substrates

The orientation controlled synthesis of h-WO3 nanostructures on ITO substrates has been successfully realized in large scale via a simple hydrothermal method. The influences of pH value and growth time on the orientation and morphology of WO3 nanostructures were investigated by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The nanorod bundles parallel to ITO substrate and nanorod arrays vertical to ITO substrate can be selectively prepared by adjusting the final pH value just to 2.0 and 2.4, respectively. The morphology evolution and the growth mechanism of well aligned WO3 nanorod arrays were intensively studied. Moreover, the optical properties of the WO3 with different oriented alignment were also examined.

Wafer-Scale Growth of ITO Nanorods by Radio Frequency Magnetron Sputtering Deposition

We demonstrate synthesis of tin-doped indium oxide (ITO) nanorods on 2-in. glass wafers via radio frequency (rf)-magnetron sputtering deposition. The nanorods possessed a single-crystal structure of bixbyite, grew along the <100> orientation of the cubic unit cell, and were vertically aligned to the substrates. Height and diameter of the nanorods were as large as ∼810 nm and 40–100 nm, respectively. The morphological, structural, compositional, optical, and electrical properties of the ITO nanorods were examined with respect to growth temperature (25–500°C) and growth time (10–60 min). ITO nanorod films synthesized at 500°C exhibited excellent electrical and optical property such as a low sheet resistance (∼41 Ω/□) and high transparency in the wavelength range of visible light (i.e., ∼87% transmission at 550 nm). The facile approach to synthesize ITO nanorods at a large scale demonstrated in this work may find various applications including the fabrication of high performance optoelectronic devices.

Size- and Orientation-Dependent Photovoltaic Properties of ZnO Nanorods

ZnO nanorod arrays on an ITO substrate and nanorod powder have been prepared via a chemical method in aqueous solution at low temperature. Two dimensions of composite nanorods in the arrays were obtained by controlling the reaction time. SEM, XRD, UV−vis transmission, and PL measurements have been utilized to characterize the samples. The surface photovoltage (SPV) spectra of the three samples have been comparatively investigated by a lock-in amplifier with dc bias and Kelvin probe (KP) based measurements. The kinetic features of SPV responses are interpreted in terms of ac SPV phase spectra and SPV transients on a KP. We demonstrate that the photovoltaic properties of ZnO nanorods not only depend on the rod size, but also rely on the crystallographic orientation. The mechanisms therein have been discussed in detail. Our results could lead to better understanding of the photovoltaic properties in ZnO nanostructures.

Films and nanorods of transparent conducting oxide ITO by a citric acid sol route

We report the synthesis of nanorods of Sn-doped In2O3 (ITO) through sol electrophoresis with a template. A citric acid-based sol was developed for the formation. This technique enables the synthesis of ITO nanorods with controlled size and Sn-doping concentration. The nanorods synthesized have diameters of ∼75–145 nm and show a bulk resistivity of ∼5 Ω cm.

Synthesis of ITO nanowires and nanorods with corundum structure by a co-precipitation-anneal method

Tin-doped indium oxide (ITO) nanowires and nanorods were synthesized by a co-precipitation-anneal process. Both the nanowires and the nanorods had nearly uniform diameter of ca. 60 nm. The nanowires had long and straight morphology with length up to several micrometers. Moreover, the products were the ITO with corundum structure.