Doped Zinc Oxide Research Articles

Evaluating the biomedical potential of phytomediated silver doped zinc oxide nanoparticles derived from n-butanol fraction of Adiantum venustum D. Don

Cancer and bacterial antibiotic resistance are the first two pressing issues confronting the pharmaceutical industry today. With this in mind, the current goal of this research is to create eco-friendly, green synthesized nanostructures that have the potential to at least partially eliminate these issues. The research aims to synthesize ZnO (zinc oxide) and Ag-doped ZnO (silver doped zinc oxide) nanoparticles with two different concentrations (AgxZn1-xO) and variations in their biological potential. To the best of our knowledge, the n-butanol fraction of A. venustum is being used as a first attempt to synthesize Ag-doped ZnO nanoparticles that too with varying concentrations. The XRD (X-ray diffraction) technique endorses the materialization of wurtzite structure for zinc oxide (ZnO–B) and hexagonal wurtzite configuration for the silver-doped complexes (AgZnO–B1 and AgZnO–B2). The Scherrer formula was utilized to examine the average crystallite sizes of ZnO–B (29.21 nm), AgZnO–B1 (22.03 nm), and AgZnO–B2 (27.76 nm). Using transmission electron microscopy micrographs, the grain sizes of AgZnO–B1 (57.72 ± 1.84 nm), AgZnO–B2 (75.31 ± 2.03 nm), and ZnO–B (45.84 ± 0.57 nm) were measured. The XPS (X-ray Photoelectron Spectroscopy) revealed the Zn2+ and Ag + oxidation state of green synthesized nanoparticles. Additionally, the antioxidant, anti-inflammatory, antimicrobial and anticancer activities were assessed in relation to the n-butanol fraction of A. venustum and the synthesized nanomaterials. Of all the synthesized nanoparticles, AgZnO–B1 has proven to be a potent biomedical agent in all biological activities. AgZnO–B1 was found to have potential as an anti-inflammatory (IC50- EAA 33.63 ± 0.05 μg/mL; BSA 28.02 ± 0.80 μg/mL) and anticancer (IC50 85.27 μg/mL) agent in the study. Therefore, it should be underlined that nanoparticles have enormous biological efficacy and used in a range of therapeutic contexts.

ZnO nanostructures grown from spent batteries: Ambient catalytic aspects and novel mechanistic insights

The present work includes a facile and economic microwave assisted hydrothermal synthesis of Zinc Oxide (ZnO), Diethylene Triamine Pentaacetic Acid (DTPA) stabilized Zinc Oxide (ZD) and DTPA stabilized Silver doped Zinc Oxide (ZAD) nanostructures using Zn from spent alkaline batteries. The synthesised nanostructures were well characterised using electronic, vibrational and X-Ray spectroscopic techniques as well as thermal and microscopic techniques revealing the successful stabilisation of DTPA in ZD and doping of Ag in ZAD. The Fourier Transform Infrared Spectroscopy (FTIR) spectra showed peaks characteristic to the presence of ZnO in the fingerprint region and those to the presence of DTPA. The X-Ray Diffraction Spectroscopy (XRD) pattern of ZnO, ZD and ZAD indicated the hexagonal wurtzite structure of ZnO and face centred cubic metallic Ag in ZAD. The Transmission Electron Microscopy (TEM) images revealed rod shaped morphology for ZnO and spherical morphologies for ZD and ZAD. The nanostructures proved to be efficient catalysts to achieve 100 % degradation of Malachite Green, Crystal Violet and Reactive Blue-21 and their binary mixtures under ambient conditions in presence of Hydrogen peroxide (H2O2). ZAD exhibited relatively rapid degradation with rate constants 0.754 min−1, 0.187 min−1 and 0.0150 min−1 for MG, CV, and RB-21 respectively as well as 99 % reduction in Chemical Oxygen Demand (COD) value of the dye solutions. Scavenging studies and Electron Paramagnetic Resonance (EPR) studies using different spin trapping agents revealed the involvement of singlet oxygen species, hydroxyl radicals (OH.) and superoxide radicals (O2.-) in the degradation process. This work aligns with Sustainable Development Goals 6, 12 and 13.

Mg doped ZnO containing silk nanocomposite scaffolds for biofilm prevention during alveolar bone regeneration

Biofilms are created when micro-colonies adhere to a solid surface and produce a strong extracellular matrix which increases the risk of infection and impedes the healing process of bone defects. Although post-operative antibiotics are commonly prescribed to prevent infections, they carry the risk of side effects and antibiotic resistance. Current research explored the potential of magnesium doped zinc oxide incorporated silk fibroin scaffolds to prevent the biofilms formation for alveolar bone regeneration applications. Novel silk fibroin (SF)/hydroxyapatite (HA) scaffolds incorporated with magnesium-doped zinc oxide nanoparticles (Mg–ZnO NPs with 0.5, 1 and 2 % Mg) were fabricated by freeze gelation method. The data suggested that new materials exhibit remarkable antibacterial activity against Staphylococcus aureus. Moreover, these materials are also found to be both biodegradable and biocompatible. The study revealed that scaffolds displayed excellent antibacterial activity that was increased with increasing concentration of Mg in ZnO, with a maximum of 49.39 % was observed for 2 % of Mg doped ZnO. Additionally, biodegradation of the material also increases with the increase in concentration of Mg doping in ZnO. The adequate porosity in the range of 67 %–74.3 % was recorded of new materials substituted with Mg–ZnO, which led to improved cell viability (99.6 %) and uniform deposition of apatite over the surface of scaffolds, making it an excellent candidate for biomedical applications that require antibacterials properties with high cell viability.

Sustainable and facile fabrication of chitosan-coated silver-doped zinc oxide nanocomposites exploiting Bergera koenigii foliage for enhanced photocatalysis and antibacterial activity

Industrial and academic chemical pollutants such as Eriochrome Black-T (EBT) and murexide dyes are widely used in academic institution as well as industries, when eluted into rivers, delineate the ill effect on human and aquatic life. Herein, green and ecofriendly synthesis of silver doped-Zinc oxide nanoparticles (Ag/ZnO NPs) and chitosan coated Ag/ZnO nanoparticles (CS/Ag/ZnO NPs) using Bergera koenigii extract to solve environmental issues have been reported for the first time. Spherical and agglomerated particles with crystalline flakes like morphology of Ag/ZnO NPs and CS/Ag/ZnO NPs respectively have been ascertained by Scanning electron morphology (SEM) analyses and XRD. XRD analysis revealed the average crystallite size of 42.16 nm and 48.45 nm for Ag/ZnO NPs with 5 % and 10 % Ag concentration respectively, lesser than crystallite size of 47.394 nm and 52.38 nm for CS-5 % Ag/ZnO NC and CS-10 % Ag/ZnO NC respectively. All the synthesized NPs and NC demonstrated remarkable antibacterial potential against both gram +ve and gram -ve bacteria. Additionally, all the materials showed very high time-dependent photocatalytic degradation activity (>98 %) of EBT and murexide in 12 min. Remarkably, all active nano-catalysts exhibit high durability, and displayed recyclability for >8 cycles. In nutshell, chitosan coated nano-catalyst showed drastic improvement in photocatalytic and antibacterial activities.

Boosted adsorptive removal of eosin yellow dye from aqueous solution with C–ZnO nanoparticles: optimization of process parameters

This study investigates the effectiveness of ultrasound-aided sorption using carbon–doped zinc oxide nanoparticles (C–ZnO NPs) for the removal of eosin yellow dye (EY) from wastewater. Raman spectroscopy was employed to confirm the successful carbon doping in the ZnO lattice, while field emission scanning electron microscopy (FESEM) was used to observe the morphology of the C–ZnO NPs, revealing uniform pseudo-spherical grains with diameters ranging from 20 to 35 nm. The impact of important parameters such as EY base concentration (50–200 mg/L), C–ZnO NPs dose (0.125–1.0 g/L), initial solution pH (2.0–10.0), and reaction time (1–30 minutes) on EY dye removal was investigated to assess the adsorptive potential of C–ZnO NPs. The highest sorption efficiency of 95.90 ± 0.96 % for EY dye was achieved within 20 minutes using C–ZnO NPs dose of 0.50 g/L, a solution pH of 4.0, and at an EY base concentration of 50 mg/L. The adsorption followed pseudo-second-order kinetics and Langmuir isotherm, with a sorption capacity of 232.59 ± 1.36 mg/g. Sono-assisted adsorption outperformed with a performance of 98.96% ± 0.85% as compared with conventional methods like magnetic stirring and overhead stirring, which had a performance of 73.24% ± 1.90% and 78.06% ± 2.0% respectively. C–ZnO is found to be a cost-effective adsorbent due to its low production cost of 31.0 $/kg and high reusability. As a result, this work emphasizes the prospective use of C–ZnO NPs as adsorbent for EY removal from wastewater on account of high sorption efficiency, superior adsorptive performance over ZnO NPs, and its cost effectiveness.

Influence of copper on zinc oxide films and solar cell performance

Copper doped Zinc oxide and (n-ZnO / p-Si and n-ZnO: Cu / p-Si) thin films thru thickness (400±20) nm were deposited by thermal evaporation technique onto two substrates. The influence of different Cu percentages (1%,3% and 5%) on ZnO thin film besides hetero junction (ZnO / Si) characteristics were investigated, with X-ray diffractions examination supports ZnO films were poly crystal then hexagonal structural per crystallite size increase from (22.34 to 28.09) nm with increasing Cu ratio. The optical properties display exceptional optically absorptive for 5% Cu dopant with reduced for optically gaps since 3.1 toward 2.7 eV. Hall Effect measurements presented with all films prepared pure and doped have n-types conductive, with a maximum carriers concentrate of 3.9×1016 (cm-3 ) besides lower resistivity of 59.6 (Ω.cm) for films doped with 5% (Cu). The current- voltage (I-V) characteristics of heterojunction below illumination by incident power density (100 mW/cm2 ) showed that heterojunction (n-ZnO: 5%Cu / p-Si) has maximum efficiency (η =3.074 %).

Enhanced sunlight-driven photocatalysis of non-metal doped zinc oxide via wet impregnation for the removal of organic compounds

Zinc oxide (ZnO), a commonly used photocatalyst, suffers from the rapid recombination of photogenerated charge carriers, and the inability to harvest visible light. Therefore, the green synthesized ZnO from Garcinia mangostana pericarp is modified via non-metal (X) doping of N, P, S, Br, and B with a mass content of 5 % to tackle the aforementioned. The obtained materials were characterized through various modern characterization techniques. The results reveal that amongst the X-doped sample, ZnO-B demonstrates the highest photocatalytic performance. The characteristics of ZnO include good crystallinity as well as a low band gap energy of 2.094 eV, revealing an enhanced visible light absorption activity of the sample. The photoactivity of surveyed ZnO-B was investigated through the degradation of malachite green, methyl orange, and tetracycline, achieving a removal rate of 96.29, 86.59, and 90.32 %, respectively. Simultaneously, the antibacterial properties of the ZnO-X were evaluated for Staphylococcus aureus under sunlight illumination. Moreover, the photocatalysis mechanism of the studied materials was elucidated through the band structure, toxicity, and total organic carbon removal of the post-catalysis solution. The selected boron-doped zinc oxide catalyst also showed excellent reusability after 10 cycles of photocatalysis, retaining ∼ 80 % of its original activity. The obtained results reveal the potential application of non-metal-doped zinc oxide in environmental remediation and water disinfection.

Structural and optical studies of copper doped zinc oxide thin films synthesized by co-precipitation method

This study presents the fabrication and characterization of pure and copper doped zinc oxide (Cu-doped ZnO) thin films with varying copper concentrations. The films were synthesized using co-precipitation and spin coating methods, followed by post-annealing at 450 °C for 6 h in ambient air. Structural and optical properties of the samples were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and Raman spectroscopy. Structural analysis revealed a decrease in average crystalline size up to 2 wt% copper doping, followed by an increase with higher doping concentrations. SEM micrographs supported these findings. The band gap of the samples narrowed with increasing copper doping, from approximately 3.22 eV for pure ZnO to 2.72 eV for the 6 wt% copper doped sample. Furthermore, frequency variations in the 400–600 cm−1 wavelength interval were observed in the FTIR vibrational bands of zinc oxide due to increasing copper doping.

Sandwich probe temperature sensor based on In2O3-IZO thin film for ultra-high temperatures

High-temperature thin-film thermocouples (TFTCs) have attracted significant attention in the aerospace and steel metallurgy industry. However, previous studies on TFTCs have primarily focused on the two-dimensional planar-type, whose thermal sensitive area has to be perpendicular to the test environment, and therefore affects the thermal fluids pattern or loses accuracy. In order to address this problem, recent studies have developed three-dimensional probe-type TFTCs, which can be set parallel to the test environment. Nevertheless, the probe-type TFTCs are limited by their measurement threshold and poor stability at high temperatures. To address these issues, in this study, we propose a novel probe-type TFTC with a sandwich structure. The sensitive layer is compounded with indium oxide doped zinc oxide and fabricated using screen-printing technology. With the protection of sandwich structure on electrode film, the sensor demonstrates robust high-temperature stability, enabling continuous working at 1200 °C above 5 h with a low drift rate of 2.3 °C·h−1. This sensor exhibits a high repeatability of 99.3% when measuring a wide range of temperatures, which is beyond the most existing probe-type TFTCs reported in the literature. With its excellent high-temperature performance, this temperature sensor holds immense potentials for enhancing equipment safety in the aerospace engineering and ensuring product quality in the steel metallurgy industry.

Synthesis of Ag Doped ZnO Nanowire by Hydrothermal Method and its Characterization

This research is mainly focused over synthesizing zinc oxide (ZnO) nanowire (NW) and silver doped zinc oxide nanowires (Ag/ZnO) using two step hydrothermal method which comprises of seed layer deposition and hydrothermal nanowire growth step. Hydrothermally grown nanowires are of great significance. The synthesized nanowires were characterized by UV-Vis Spectroscopy (UV-Vis), X- ray Diffraction Spectroscopy (XRD), Energy Dispersive Spectroscopy (EDS), Field Emission Scanning Electron Microscopy (FE-SEM) and High-Resolution Transmission Electron Spectroscopy (HR-TEM). XRD pattern revealed as-synthesized materials are of crystalline nature having crystallite size of 166.27 nm and 42.32 nm for ZnO nanowire and Ag doped nanowire, respectively. Further confirmation was done by EDS, SEM and TEM. The microscopic images of SEM and TEM evidenced for successful fabrication of nanowires.

Investigation studies of pure and molybdenum doped zinc oxide thin films deposited by spray pyrolysis technique for transparent conductive oxides applications

Investigation studies of pure and molybdenum doped zinc oxide thin films deposited by spray pyrolysis technique for transparent conductive oxides applications

Tuning the structural, optical and magnetic properties of transition metal doped zinc oxide nanoparticles

Tuning the structural, optical and magnetic properties of transition metal doped zinc oxide nanoparticles

Plasmonic Al, Ga and in-doped zinc oxide nanoparticles as key components for the design of electrophoretic inks with MWIR and LWIR absorbance properties

Doped zinc oxide nanocrystals (NCs) are halfway through semiconductors and metals. They exhibit unique optoelectronic properties from a high surface density of free-charge-carriers, which are responsible for localized surface plasmon resonance (LSPR). Here, a one-pot approach is presented to synthesize doped aluminum, gallium or indium zinc oxide NCs, making them all stable in non-polar media. The effect of doping on the growth mechanisms and the final crystalline structure were studied as a function of the aliovalent doping atom used. Doping atoms were integrated by substitution of Zn atom into the crystalline mesh of ZnO with a wurtzite phase identified as the primary crystalline phase for all samples by X-ray Diffraction (XRD). Typical aluminiun doped ZnO NCs (AZO) or Gallium doped NCs (GZO) nanoflowers were identified as a single crystalline structure by High-Resolution-Transmission Electron Microscopy (HR-TEM). Indium doped ZnO NCs (IZO) and pristine ZnO appeared significantly different with spherical and heart-like shapes, respectively. The doping level tendency was identified through Energy Dispersive X-ray (EDX) and increased form Al to Ga and In doping atoms. All plasmonic doped NCs have broadband infrared absorption in the Middle-wave (MWIR) and Long-wave infrared (LWIR) wavelengths, making them interesting for thermal regulation or thermal camouflage. As part of the latter application, dispersions of doped ZnO NCs were formulated as electrophoretic inks and their IR-absorbing performances determined by using a homemade setup including an infrared camera. AZO, GZO, and IZO NCs based inks achieved temperature contrasts of 15 °C and 6 °C in the MWIR and LWIR wavelengths.

PRELIMINARY STUDY ON PERFORMANCE OF Zn-DOPED ZEOLITE IN LOW-TEMPERATURE CO2 ADSORPTION

Zeolite has been identified as a potential low-temperature CO₂ adsorbent with the highest adsorption capacity among adsorbents in its category. However, its adsorption capacity remains relatively low, limiting its industrial application for CO₂ adsorption. Additionally, there is a need to increase the optimal adsorption temperature of this porous material to effectively adsorb CO₂ emitted from flue gas, which has an average temperature of 100 - 125°C. To address these challenges, a preliminary study on Zn-doped zeolite has been conducted. This study aims to investigate the ability of Zn-doped zeolite to enhance CO₂ adsorption capacity and its effect on the optimal temperature for CO₂ adsorption. Zinc-doped zeolite was synthesized by doping zinc oxide into natural zeolite using a zinc ion exchange method at different doping concentrations (0.2 M & 1.0 M). Undoped natural zeolite was studied as a benchmark. Their CO₂ adsorption performance was tested using TGA at 30°C, 50°C, and 100°C. The effects of temperature and doping concentration on adsorption capacity were investigated. The adsorbent samples were characterized using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX) analysis. It was found that increasing the temperature from 30°C to 50°C increased the CO₂ adsorption capacity, but the capacity decreased when the temperature was further increased to 100°C. Furthermore, increasing the doping concentration tended to enhance the CO₂ adsorption capacity. The highest adsorption capacity of 0.0281 g CO₂/g sorbent was observed in zinc-doped zeolite with a 1.0 M doping concentration at 50°C. The improvement was mainly attributed to the zinc oxide doped on the zeolite, which provided a functional group that formed chemical bonds with CO₂. This study also found that the adsorption rate of CO₂ was predominantly influenced by temperature, while the effect of doping concentration was less significant. All testing and characterization results suggested that the zinc-ion exchange method improved the CO₂ adsorption capacity of zeolite.

Comprehensive study for radiation shielding features for Bi2O3–B2O3–ZnO composite using computational radioanalytical Phy-X/PSD, MCNP5, and SRIM software

The current study uses zinc oxide doping nanoparticles to investigate the radiation shielding properties of bismuth borate glass. Fourier transform infrared (FTIR) and X-ray diffraction (XRD) examined the structural characteristics of the current samples. In contrast, the optical properties were determined based on the absorption spectrum for current samples. Appraisal studies are carried out depending on the simulation capabilities of Phy-X/PSD software in conjunction with MCNP5 to achieve this goal. In addition, the neutron and charged particle shielding properties were evaluated theoretically. All glasses are amorphous, as confirmed by the XRD data, and the FTIR data showed several vibration bands and functional groups. The density showed rising from 5.981 to 6.433 g/cm3 with adding ZnO. The band gap values reduced from 2.831 to 2.091 eV for direct and 3.024 to 2.218 eV for indirect with adding ZnO. The investigations' findings demonstrate a strong agreement between the theoretical and simulation-derived estimates of the mass attenuation coefficient. The relative difference of MAC results lie in the range 0.106–2.941% for BBZ0, 0.105–4.348% for BBZ1, 0.105–3.398% for BBZ2, and 0.105–2.032% for BBZ3. The study's findings are valuable insights from thoroughly examining these parameters, which can potentially improve the radiation protection abilities of Bi2O3–B2O3–ZnO glasses. This study represents a significant step in developing more efficient and safer materials for gamma radiation shielding applications.

Biogenically Synthesized ZnO and Cu-Doped ZnO Nanoparticles: Effect of Cu-Dopent Concentration and Annealing on Morphology and Optical Properties

In this work, ZnO nanoparticles and Cu-doped ZnO nanoparticles were biogenically synthesized using precipitation method in <i>Cissus quadrangularis</i> plant extract medium. The influence of Cu dopant on the crystalline structure, optical properties, and morphology of ZnO was investigated. The samples were characterized by XRD, FTIR, UV–vis spectroscopy and SEM. XRD patterns confirmed the wurtzite formation of doped and undoped ZnO nanoparticles. The average crystallite size of the neat and Cu-doped samples was ~18 nm irrespective of the amount of dopant. The annealing process enhanced the size of both the neat and Cu-doped samples. However, the influence on the size is less prominent in the Cu-doped sample than in the neat sample. The UV-visible spectral analysis shows that all the synthesized doped and undoped nano zinc oxides absorb at ~400nm. The band gap energy of Cu-doped ZnO particles was greater for unannealed samples whereas it was appreciably lowered on annealing for Cu-doped samples. SEM analysis shows rod-like morphology for the unannealed and annealed undoped zinc oxides. It is changed to flower-like morphology with the addition of 5mM Cu<sup>2+</sup> and then to nano sheet-like structure with the incorporation of higher amount of Cu<sup>2+</sup> ions. Annealing of zinc oxide samples leads to the smoothening of the surfaces with a change in morphology for the ZnO nanoparticles.

Tailoring the structural, optical, hydrophobicity and electrical properties of ZnO thin films by copper doping for self-clean optoelectronic application

Optoelectronic devices such as solar panels, cameras, screens, and sensors frequently suffer reduced performance due to dust accumulation. Incorporating self-cleaning features not only sustains their efficiency but also minimizes maintenance expenses, especially for large or challenging-to-access setups. In this study, copper doped-zinc oxide (CZO) thin films with varying copper (Cu) concentrations were created using the reactive co-sputtering process. These films underwent a comprehensive analysis, including X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy to examine their structure, morphology, and elemental composition. Optical properties were investigated through UV–Vis spectroscopy, while hydrophobicity and electrical characteristics were assessed with contact angle and I–V measurements. Spectroscopic ellipsometry was employed to analyse surface attributes. The results confirmed that as Cu concentrations increased, the crystallite and grain size of ZnO in the films also increased. A red shift in the band gap was observed in UV–Vis spectroscopy, and Cu doping effectively reduced the electrical resistivity of the ZnO thin film. The CZO thin film, with a 60 nm thickness, low roughness (1.49 nm), high optical transmittance (around 80.20 %), a wide band gap (3.22 eV), a substantial contact angle (113°), and low electrical resistivity (5.9 × 105 Ω cm), holds great promise for use in transparent, conductive, and self-cleaning optoelectronic devices.

Photocatalytic, antibacterial and optoelectronic applications of Terbium doped Zinc oxide nanoparticles prepared via chemical co-precipitation method

This work demonstrates facile synthesis of Tb-doped ZnO nanoparticles and investigates their structural, optical, electrochemical, photocatalytic, and antibacterial performance. XRD patterns of undoped and doped ZnO nanoparticles confirm a hexagonal wurtzite structure. TEM and SAED reveals that the particle size is 14–38 nm. SEM images show that ZnO and Tb-doped ZnO nanoparticles have smooth surfaces, and elemental composition was confirmed by EDX analysis. UV–Visible spectrophotometry studies, reveals that the band gap narrows with increasing Tb concentration. Photoluminescence spectra at room temperature showed a band at 538 nm, indicating zinc vacancies and green emission. Tb-doped ZnO with x = 0.075 exhibited the highest photocatalytic activity for degrading Rose Bengal dye compared to other photocatalysts. The electrochemical behaviour of Catechol (CC), Hydroquinone (HQ), and Bisphenol-A (BPA) at Tb–ZnO/MCPE was studied. The modified electrode process for CC and BPA was adsorption-controlled, and simultaneous recognition of CC, HQ, and BPA was achieved, showing an increase in current. Electro polymerization of poly (Congo red) on Tb–ZnO/MCPE confirmed clean deposition on the surface, enhancing electrocatalytic activity. The antibacterial efficacy was tested using the traditional disc diffusion method, showing effective inactivation of bacterial strains, including pathogens such as S. aureus (G+) and E. coli (G-).

Investigation on optical and electrical properties of multilayer ITO/AZO/ITO transparent conductive oxides

This paper examines how varying the thickness of the indium tin oxide (ITO) seed layer, ranging from 8 to 20 nm, impacts the optical, electrical, and structural properties of triple-layer transparent conductive oxide ITO/aluminum doped zinc oxide (AZO)/ITO. ITO and AZO films were deposited by DC and RF magnetron sputtering, respectively. The thickness and density of each layer were measured by X-ray reflectometry (XRR). X-ray diffraction showed that as the thickness of the ITO seed layer increased, both the average size of the crystallites and the volume of the crystalline phase in the AZO film also increased. Measurements of the electrical characteristics indicated a decrease in resistivity as the thickness of the ITO seed layer increased. This reduction is attributed to enhanced charge mobility, resulting from improved crystallinity. It has been shown that a 20-nm-thick ITO seed layer is sufficient to achieve a charge mobility comparable to that of pure ITO films. The photoluminescence spectra have shown a decrease in the concentration of the oxygen vacancies with the introduction of both the cover and seed layers of ITO. The figure of merits (FOM) of the triple-layer coatings and the optical constants of the AZO and ITO films were calculated. The results of this paper indicate that the ITO20/AZO48/ITO12 triple-layer coating possesses optimal characteristics for use in high-efficiency silicon solar cells.

Investigation of an absorption plasmonic electro-optical modulator based on the free carrier dispersion effect in the aluminum doped zinc oxide layer

A plasmonic electro-optical modulator, which is based on the free carrier dispersion effect, has been introduced here. The structure of the proposed modulator is a substrate of fused silica/gold/aluminum doped zinc oxide/hafnium dioxide/gold/air. The free carrier dispersion effect occurs in the aluminum doped zinc oxide (AZO) layer. As the electrical permittivity of the AZO layer is near zero (the epsilon near zero effect) at a wavelength of 1.55 μm, the amplitude of an electrical field is high in this layer, therefore, the modulator is highly sensitive to the varying refractive index of this layer. By applying a voltage to two gold layers, the electrical charge density changes in the AZO layer. Therefore, the real and imaginary parts of the refractive index have been changed, which led to a change in the absorption of the modulator. In order to obtain the charge density distribution in the AZO layer, the Poisson equation is solved by using the finite difference method. To investigate modulator absorption, the Nelder-Mead method is implemented in order to solve the dispersion equation numerically. Finally, the magnetic field, the electric field, and the time average of the Poynting vector have been given by using the least squares approximation method.