Structure Of Indium Tin Oxide Research Articles

Transparent ultrawideband polarization-insensitive absorber with optimal thickness based on a grid ITO structure

With the large-scale commercialization of broadband wireless communication technologies, interference between spatial electromagnetic waves (EMWs) is becoming increasingly serious. As devices for solving electromagnetic interference (EMI) problems, microwave absorbers (MAs) have become increasingly mature with the rapid development of artificial electromagnetic structures. However, current MAs still face challenges in terms of wideband absorption, wide-angle absorption, thickness, etc., which limits their application scenarios. Therefore, this paper proposes a transparent ultrawideband polarization-insensitive absorber based on a grid indium tin oxide (ITO) structure. This design adopts a multilayer structure with a total thickness of 3.525 mm (0.114λ L ), close to the predicted minimum thickness, to expand the bandwidth. The grid-patterned ITO film resonant structure and ITO film ground plane are designed to further improve optical transmittance by increasing duty ratios. Simulation results demonstrate over 90% absorption from 9.7 GHz to 69.2 GHz, with a fractional bandwidth (FBW) of 150.8%. The absorber has good incident angle stability and polarization insensitivity. When the incident angle varies within 0-60°, the proposed absorber maintains an absorption close to 80% over an ultrawideband range, and the absorption remains nearly constant when the polarization angle changes from 0° to 90°. The fabricated sample shows a visible light transmittance of approximately 73.2%, and shows an absorption performance consistent with simulations in the 6-38 GHz frequency range, validating the effectiveness of the proposed design. Due to its transparent, ultrawideband absorption, wide incident angle stability and polarization insensitivity properties, this proposed absorber has important guiding significance for applications in high-frequency transparent electronics, radars, communications systems and other devices working in the microwave frequency band.

Ellipsometry, transmission, and photoluminescence characterization of Mn-doped ITO thin films deposited by DC magnetron sputtering

Manganese-doped indium tin oxide (ITO) thin films (0–12.8 at% Mn) were deposited by DC magnetron sputtering. The structural, electrical, and optical properties of the films were studied. Optical characterization was emphasized and included ellipsometry, transmission, and photoluminescence (PL) measurements. Features of the energy band structure of ITO and Mn-ITO were extracted from PL spectra and Tauc analyses of absorption data. We concluded that the fundamental bandgap of ITO is ∼2.8 eV. A separate deep valence band, ∼0.8 eV below the valence band maximum, was confirmed to be involved in higher energy optical absorption and emission transitions. Both of these observations were consistent with recent published theoretical studies and spectroscopic measurements (XPS, XES, etc). Mn addition was found to result in a decrease of the transition energies. Additionally, Burstein–Moss shifts were observed.

Effect of substrate type on the physical properties of thermally evaporated CdS thin films for CdTe/CdS solar cells applications

Cadmium Sulfide (CdS) thin films were grown on crystal quartz as a nonconductive substrate, and Indium tin oxide (ITO) and Fluorine doped tin oxide (FTO) as transparent conducting oxide (TCO) films. The thin films with the thickness of 100 nm were fabricated at 150 °C under the pressure of 2 × 10−5 mbar using the thermal evaporation method. The x-ray diffraction (XRD) results showed that all grown CdS films had cubic crystal structures with the preferred orientation (111) and a crystallite size between 11.72 nm and 14.84 nm. Raman spectra also revealed an increase in peak intensity and shift toward single-crystal mode in the films grown on TCOs. The homogeneous and uniform surfaces of CdS films were shown in scanning electron microscopy (SEM) images. The optical parameters of the deposited CdS thin films such as absorption, transmission, refractive index, extinction coefficient, and real and imaginary parts of dielectric constant, were improved. The energy band gap of the films was decreased from 2.45 eV for the CdS/quartz film to 2.36 eV for the CdS/FTO one. The key electrical parameters of the deposited films on TCO, such as conductivity, mobility and carrier concentration, as calculated by the Hall effect measurement system, were enhanced too. High efficient heterojunction cadmium telluride (CdTe)-based solar cells with the experimentally grown CdS films were designed by SCAPS-1D simulator. The efficiency of the designed cells with CdS/quartz, CdS/ITO, and CdS/FTO layers was obtained to be 19.40%, 21.23%; and 21.16%, respectively. The impact of the CdTe absorber layer thickness and device temperature on the photovoltaic parameters of the simulated cells was then investigated. The optimized cell was obtained for an Au/CdTe/CdS/ITO structure with the efficiency of 22.80% by employing a 3 μm thickness of the CdTe layer at a device temperature of 300 K.

Compact TE-pass polarizer based on lithium-niobate-on-insulator assisted by indium tin oxide and silicon nitride

An indium tin oxide (ITO) and silicon nitride (Si3N4) assisted compact TE-pass waveguide polarizer based on lithium-niobate-on-insulator is proposed and numerically analyzed. By properly designing the ITO and Si3N4 assisted structure and utilizing the epsilon-near-zero effect of ITO, the TM mode is strongly confined in the ITO layer with extremely high loss, while the TE mode is hardly affected and passes through the waveguide with low loss. The simulation results show that the polarizer has an extinction ratio of 22.5 dB and an insertion loss of 0.8 dB at the wavelength of 1.55 μm, and has an operating bandwidth of about 125 nm (from 1540 nm to 1665 nm) for an extinction ratio of > 20 dB and an insertion loss of < 0.95 dB. Moreover, the proposed device exhibits large fabrication tolerances. More notably, the device is compact, with a length of only 7.5 μm, and is appropriate for on-chip applications.

Dual-Functional Enantiomeric Compounds as Hole-Transporting Materials and Interfacial Layers in Perovskite Solar Cells.

In this paper, we describe the application of the enantiomeric compounds YLC-1-YLC-4, each featuring a bulky spiro[fluorene-9,9'-phenanthren]-10'-one moiety, as both hole-transporting materials (HTMs) and interfacial layers in both n-i-p and p-i-n perovskite solar cells (PSCs). These HTMs contain an enantiomeric mixture and a variety of core units linked to triarylamine donors to extend the degree of π-conjugation. The n-i-p PSCs incorporating YLC-1(a) exhibited a power conversion efficiency (PCE) of 19.15% under AM 1.5G conditions (100 mW cm-2); this value was comparable with that obtained using spiro-OMeTAD as the HTM (18.25%). We obtained efficient and stable p-i-n PSCs having the dopant-free structure indium tin oxide (ITO)/NiOx/interfacial layer (YLC)/perovskite/PC61BM/BCP/Ag. The presence of the spiro-based compounds YLC-1 and YLC-2 efficiently passivated the interfacial and grain boundary defects of the perovskite and enhanced the sizes of its grains, more so than did YLC-3 and YLC-4. These spiro-based YLC derivatives packed densely and functioned as Lewis bases to coordinate Pb and Ni ions in the perovskite and NiOx layers, respectively. Together, the effects of smaller grain boundaries and defect passivation of the perovskite enhanced the optoelectronic properties of the PSCs. The photoinduced charge carrier extraction in the linearly increasing voltage (photo-CELIV) curves of NiOx/YLC-1(a) showed the faster carrier transport 3.3 × 10-3 cm2 V-1 s-1, which improved the carrier mobility, supporting the notion of defect passivation of the perovskite. The best-performing NiOx/YLC-1(a) device provided a short-circuit current density (JSC) of 22.88 mA cm-2, an open-circuit voltage (VOC) of 1.10 V, and a fill factor (FF) of 80.93%, corresponding to an overall PCE of 20.37%. In addition, the PCEs of the NiOx/YLC-1(a) and NiOx/YLC-4(b) PSC devices underwent decays of only 98.1 and 97.0% of their original values after 41 days under an Ar atmosphere. Thus, these YLC derivatives passivated the NiOx surface and optimized the film quality of perovskites, thereby leading to superior PCEs of their respective PSCs.

A novel strategy of fabricated flexible ITO electrode by liquid metal ultra-thin oxide film

Flexible transparent conductive films are gaining attention day by day over the last few years due to it is a key component of next generation flexible electronics and optoelectronic devices. Indium tin oxide (ITO) as one of the most widely used transparent conductive material is limited by the traditional deposition approach cannot be achieve ultra-thin, which results in its brittle nature. Herein, a novel strategy for fabricating highly transparent conductive films by liquid metal interface phase separation technique based on low-melting liquid metal of InxSn100-x alloy is reported, during the solid-to-liquid phase transition of alloy, the monolayer of surface oxide film segregated with the bulk phase and was printed on the flexible polyethylene-naphthalate (PEN) substrate under the van der Waals. This novel strategy can directly print the ultra-thin self-oxide with the structure of ITO on PEN substrate, with the resulting of transparency over 97.5% and resistivity as low as 0.21 kΩ cm, providing a new way of low-cost raw ITO material as well as the personalized preparation strategy. The desirable highly transparent conductive films are comparable to recently reported ITO film, together with advantages of pretty steady, make them attractive as various flexible transparent conductive electrodes, for example, an ultra-thin ITO film is developed for luminescent devices.

Enhanced Switching in an Argon Annealed RRAM by Ion Irradiation

The present study describes the impact of ion irradiation on the switching behaviour of zinc oxide formed on ITO substrates by RF sputtering. When annealed ZnO—ITO (Zinc Oxide—Indium Tin Oxide) structures are bombarded with Ag+8 with a fluence of 1012 ions cm−2, the resistance ratio was found to be the order 103 at 1 V. In pristine samples (annealed in argon) the resistance ratio was found to be 102 at 1 V. Variations in density defect generated by Swift Heavy Ion (SHI) irradiation gave birth to conducting filaments, which are the principal source of switching in ZnO, as opposed to changes in vacancies of oxygen at the interface.

Design and analysis of an optically transparent ultra-wideband absorber covering C-, X-, ku-, k-, ka- bands

In this paper, an optically transparent ultra-wideband electromagnetic absorber (EMA) is designed using indium tin oxide (ITO) film. To achieve a transparent property, the traditional dielectric substrate and copper are replaced by polyethylene terephthalate (PET) and ITO film. The ultra-wideband absorbing is achieved through the combination of multilayer periodic ITO structures etched on flexible PET layers. The simulation results show that the design can absorb EM waves in the frequency range of 3.72-42.42 GHz (relative bandwidth 165.75%), while its overall thickness is only 0.669λ0 (λ0 is the wavelength at the center frequency of EMA). The design also has the property of polarization insensitive and angular stability. Finally, the absorber is fabricated and measured to prove the effectiveness.

CaF2: A novel electrolyte for all solid-state electrochromic devices

The energy consumption in building ventilation, air, and heating conditioning systems, accounts for about 25% of the overall energy consumption in modern society. Therefore, cutting carbon emissions and reducing energy consumption is a growing priority in building construction. Electrochromic devices (ECDs) are considered to be a highly promising energy-saving technology, due to their simple structure, active control, and low energy input characteristics. At present, H+, OH- and Li+ are the main electrolyte ions used for ECDs. However, H+ and OH- based electrolytes have a high erosive effect on the material surface and have a relatively short lifetime. Li+-based electrolytes are limited due to their high cost and safety concerns. In this study, inspired by prior research on Ca2+ batteries and supercapacitors, CaF2 films were prepared by electron beam evaporation as a Ca2+-based electrolyte layer to construct ECDs. The structure, morphology, and optical properties of CaF2 films were characterized. ECDs with the structure of ITO (indium tin oxide) glass/WO3/CaF2/NiO/ITO show short switching times (22.8 s for the coloring process, 2.8 s for the bleaching process). Additionally, optical modulation of the ECDs is about 38.8% at 750 nm. These findings indicate that Ca2+ based ECDs have the potential to become a competitive and attractive choice for large-scale commercial smart windows.

Tailoring properties of indium tin oxide thin films for their work in both electrochemical and optical label-free sensing systems

This work is devoted to the identification properties of indium tin oxide (ITO) thin films responsible for their possible application in combined optical and electrochemical label-free sensing systems offering enhanced functionalities. Since any post-processing would make it difficult to identify direct relation between deposition parameters and properties of the ITO films, especially when deposition on temperature-sensitive substrates is considered, the films were deposited using reactive high power impulse magnetron sputtering (HiPIMS) at low temperature and with no post-deposition annealing. We focused mainly on the impact of reactive gases, such as oxygen or nitrogen introduced to the process chamber, on control over plasma parameters and subsequently properties of the films. The properties of the films were investigated using X-ray diffractometry, spectroscopic ellipsometry, four-point probe, and cyclic voltammetry. For presenting optical sensing capabilities, the tailored ITO films in addition to silicon and glass wafers were also deposited on the core of optical fibers to induce the lossy-mode resonance (LMR) phenomenon. The existence of specific deposition conditions resulting in ITO film properties offering both high-quality electrochemical and LMR responses has been experimentally proven. It has been found that the crystalline structure of ITO plays a key role in the determination of both the sensing capabilities. Finally, label-free sensing of antibody-antibody interactions in both optical and electrochemical domains for the sensor with tailored ITO film has been shown.

Simple Synthesis of Red Iridium(III) Complexes with Sulfur-Contained Four-Membered Ancillary Ligands for OLEDs

Phosphorescent iridium(III) complexes have been widely researched for the fabrication of efficient organic light-emitting diodes (OLEDs). In this work, three red Ir(III) complexes named Ir-1, Ir-2, and Ir-3, with Ir-S-C-S four-membered framework rings, were synthesized efficiently at room temperature within 5 min using sulfur-containing ancillary ligands with electron-donating groups of 9,10-dihydro-9,9-dimethylacridine, phenoxazine, and phenothiazine, respectively. Due to the same main ligand of 4-(4-(trifluoromethyl)phenyl)quinazoline, all Ir(III) complexes showed similar photoluminescence emissions at 622, 619, and 622 nm with phosphorescence quantum yields of 35.4%, 50.4%, and 52.8%, respectively. OLEDs employing these complexes as emitters with the structure of ITO (indium tin oxide)/HAT-CN (dipyra-zino[2,3-f,2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile, 5 nm)/TAPC (4,4′-cyclohexylidenebis[N,N-bis-(4-methylphenyl)aniline], 40 nm)/TCTA (4,4″,4″-tris(carbazol-9-yl)triphenylamine, 10 nm)/Ir(III) complex (10 wt%): 2,6DCzPPy (2,6-bis-(3-(carbazol-9-yl)phenyl)pyridine, 10 nm)/TmPyPB (1,3,5-tri(mpyrid-3-yl-phenyl)benzene, 50 nm)/LiF (1 nm)/Al (100 nm) achieved good performance. In particular, the device based on complex Ir-3 with the phenothiazine unit showed the best performance with a maximum brightness of 22,480 cd m−2, a maximum current efficiency of 23.71 cd A−1, and a maximum external quantum efficiency of 18.1%. The research results suggest the Ir(III) complexes with a four-membered ring Ir-S-C-S backbone provide ideas for the rapid preparation of Ir(III) complexes for OLEDs.

Preparation of Ordered Nanoporous Indium Tin Oxides with Large Crystallites and Individual Control over Their Thermal and Electrical Conductivities.

Metal oxides are considered suitable candidates for thermoelectric materials owing to their high chemical stabilities. The formation of ordered nanopores within these materials, which decreases thermal conductivity (κ), has attracted significant interest. However, the electrical conductivity (σ) of reported nanoporous metal oxides is low, owing to electron scattering at the thin pore walls and many grain boundaries formed by small crystallites. Therefore, a novel synthesis method that can control pore walls while forming relatively large crystallites to reduce κ and retain σ is required. In this study, we used indium tin oxide (ITO), which is a typical example among metal oxides with high σ. Nanoporous ITOs with large crystallite sizes of several hundred nanometers and larger were successfully prepared using indium chloride as a source of indium. The pore sizes were varied using colloidal silica nanoparticles with different particle sizes as templates. The crystal phase and nanoporous structure of ITO were preserved after spark plasma sintering at 723 K and 80 MPa. The κ was significantly lower than that reported for bulk ITO due to the phonon scattering caused by the nanoporous structure and thin pore walls. There was a limited decrease in σ even with high porosity. These findings show that κ and σ are independently controllable through the precise control of the structure. The control of the thickness of the pore walls at tens of nanometers was effective for the selective scattering of phonons, while almost retaining electron mobility. The remarkable preservation of σ was attributed to the large crystallites that maintained paths for electron conduction and decreased electron scattering at the grain boundaries.

Method of full polarization control of microwave fields in a scalable transparent structure for spin manipulation

The application of transparent conducting oxides in electronic devices like solar cells or displays is common. By transferring this technology to quantum sensing and computing in the form of microwave conductors, it is possible to benefit from the advantages of these materials. By using indium tin oxide (ITO), it is demonstrated that at an arbitrary position below the conductor, an arbitrary elliptical microwave polarization can be produced by two independent sources. This is independent of the geometry and size of the ITO, whereby a non-resonant microwave approach can be chosen. Using single nitrogen vacancy (NV) centers in diamond in combination with a cross-like ITO structure, each NV center can be addressed with an ideal (clockwise or anticlockwise) microwave polarization. By optimizing the coupling of the microwave field to the NV centers and minimizing the conductor size, the creation of smaller devices compared to common approaches is possible.

Indium tin oxide recycling from waste colour filter glass via thermal decomposition

Thermal decomposition was used to enrich indium tin oxide (ITO) from waste colour filter glass. The colour layer was destroyed through oxidation, and the ITO layer was separated from the glass substrate. With the increase in the temperature and time of thermal decomposition, the yield of ITO concentrate decreased, but the ITO recovery and enrichment ratio increased. Furthermore, the ITO could be effectively enriched at 600 °C and 8 min, where the yield, recovery and enrichment ratio of ITO were 0.06 %, 98 % and 1669, respectively. The particle size distribution of the ITO concentrate was mainly distributed in 0.1–1.3 and 2.6–42.0 μm, with cumulative percentages of 4.33 % and 95.55 %, respectively. Moreover, the crystal structure of recycled ITO was not changed. Substantial poisonous and harmful mixed flue gas are produced during thermal decomposition. After condensation and adsorption by activated carbon, the emission of mixed flue gas could be effectively controlled to avoid serious pollution to the atmospheric environment.

Highly transparent conductors for optical and microwave access to spin-based quantum systems

Spin-based quantum systems are among the best sensors in terms of sensitivity and spatial resolution for a variety of physical properties. A key factor to broaden the range of applications is the control over the microwave field used to manipulate the quantum system. We present the implementation of a transparent microwave conductor, suitable for optical read-out of a spin-based quantum sensor. For this, the interaction of an indium tin oxide (ITO) strip line on diamond with nitrogen vacancy centres was investigated. The amorphous ITO can be fabricated at room temperature, has a transmittance larger than 80% in the visible spectrum and a low resistivity. We show that these strip lines are completely scalable which enables highly homogeneous microwave fields from the nanometre up to the millimetre scale. ITO structures can therefore serve as excellent transparent microwave conductors, widening the current use of spin-based quantum sensors.

L-shaped ITO structures fabricated by oblique angle deposition technique for mid-infrared circular dichroism.

This paper proposes a mid-infrared chiral structure, which consists of L-shaped indium tin oxide (ITO) films formed on self-assembled monolayer polystyrene microspheres in two orthogonal directions by oblique angle deposition technique. Experimental results demonstrate that the structure exhibit circular dichroism (CD) responses in the range of 2.5 - 4 µm. As the thickness difference of the ITO films in the two orthogonal directions increases, the CD response enhances. The reason is that the ITO films produce cross dipoles and their bigger differences in thickness bring to bigger phase differences in optical chirality. The experimental results also demonstrate that the CD signals are evidently stronger than those of the structure consisting of silver in the mid-infrared band. This work provides a new idea for the fabrication of mid-infrared chiral structures, which have potential applications in the polarization state control of mid-infrared lasers.

Tunable WLED with UV chip based on all-inorganic perovskite quantum dots

Two major problems exist in tunable White Light-Emitting Diodes (WLEDs) that are typically composed of blue-emitting chip, yellow- and/or red-emitting phosphors: (1) the unstable hue of blue-emitting chip, and (2) the harsh conditions (such as high reaction temperature and reductive atmosphere) of traditional red-emitting phosphors. In this paper, we explore a sandwich layer WLEDs structure of ITO (Indium Tin Oxide) films + blue-, yellow- and/or red-emitting pervoskite QDs phosphors + UV-emitting chip to solve the issues. Through changing the number of layers of the three QDs, the correlated color temperature (CCT) was tuned from 8658 to 3961 K, indicating the WLED tuning from cool to warm light.

Photonic Crystal Surface Emitting Lasers with Naturally Formed Periodic ITO Structures

We have successfully demonstrated GaAs-based photonic crystal surface emitting lasers with low threshold current density of 0.45 kA/cm2 by increasing the thickness of indium-tin-oxide (ITO) top cla...

Revealing the Working Mechanisms of Planar Perovskite Solar Cells With Cross-Sectional Surface Potential Profiling

With the rapid improvement in the efficiencies of perovskite solar cells (PSCs), understanding their working mechanisms becomes more and more critical for their further optimization. In this work, Kelvin probe force microscopy (KPFM) is utilized to characterize the surface potential (SP) distribution on the cross-sectional surface of planar PSCs. Devices with regular structure Indium Tin Oxide (ITO)/ZnO/perovskite/2,2′,7,-7′-tetrakis(N,N-di-p-metho-xyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD)/Au and inverted structure Fluorine doped Tin Oxide (FTO)/nickel oxide ( $\text{NiO}_{x}$ )/perovskite/ZnO/Ag are studied. The analysis of KPFM measurement indicates that, while p-n junction forms at the perovskite/ZnO interface in regular planar PSCs, p-i-n junction exists in inverted planar PSCs with electric field peaks at perovskite/ $\text{NiO}_{x}$ and perovskite/ZnO interfaces. In addition, charge injection barriers in planar PSCs are revealed with relative SP profiles obtained under different biases. In regular PSCs, charge injection barriers are only observed at the perovskite/ZnO interface and the contact between perovskite and spiro-OMeTAD is an ideal ohmic contact, while in inverted PSCs, charge injection barriers are observed at both perovskite/ZnO and perovskite/ $\text{NiO}_{x}$ contacts. The appearance of additional charge injection barriers in inverted PSCs exacerbates the charge recombination in these devices and leads to their relatively low open-circuit voltages. Our result indicates that the inefficient charge extraction is a major problem affecting the performance of planar PSCs.

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.