Aluminum-doped Zinc Oxide Research Articles

Influence of Proton Irradiation on Thin Films of AZO and ITO Transparent Conductive Oxides—Simulation of Space Environment

Transparent conductive oxides are essential materials for many optoelectronic applications. For new devices for aerospace and space applications, it is crucial to know how they respond to the space environment. The most important issue in commonly used low-Earth orbits is proton radiation. This study examines the effects of high-energy proton irradiation (226.5 MeV) on thin films of aluminium-doped zinc oxide (AZO) and indium tin oxide (ITO). We use X-ray diffraction and electron microscopy observations to see the changes in the structure and microstructure of the films. The optical properties and homogeneity of the materials are determined by spectrophotometry and spectroscopic ellipsometry (SE). Analysis of the chemical states of the elements with X-ray photoelectron spectroscopy (XPS) gives insight into what proton irradiation changes at the surface of the oxides. All measurements show that ITO is less influenced than AZO. The proton energy and fluence used in this study simulate about a hundred years in low Earth orbit. This research demonstrates that both transparent conductive oxide thin films can function under simulated space conditions, with ITO showing superior resilience. The ITO film was more homogenous in terms of the total thickness measured with SE, had fewer defects and adsorbates present on the surface, as XPS analysis proved, and did not show a difference after irradiation regarding its optical properties, transmission, refractive index, or extinction coefficient.

Damp‐Heat–Induced Degradation of Lightweight Silicon Heterojunction Solar Modules With Different Transparent Conductive Oxide Layers

ABSTRACTLightweight photovoltaic applications are essential for diversifying the solar energy supply. This opens up vast new scenarios for solar modules and significantly boosts the capacity of renewable energy. To ensure high efficiency and stability of the solar modules, several challenges need to be overcome. Degradation due to elevated temperature and/or humidity is a critical concern for silicon heterojunction (SHJ) solar modules. Here, we investigated the stability and degradation mechanism of encapsulated cells with lightweight configurations where the cells are based on three different types of transparent‐conductive oxide (TCO): indium tin oxide (ITO), aluminum‐doped zinc oxide (AZO), and a combination of ITO/AZO/ITO under humid and thermal environmental conditions. A damp heat (DH) test at a temperature of 85°C and relative humidity (RH) of 85% was performed on lightweight modules for 1000 h. Our results show that AZO is the most susceptible to DH degradation. The AZO film was damaged by the combined effects of moisture ingress and delamination of the interconnection foil, resulting in a decrease in the conductivity of the AZO film, leading to a dramatic increase in Rs and a decrease in FF of the modules. Consequently, moisture has a greater chance of percolating through the damaged AZO layer into the a‐Si:H passivation layer, causing passivation degradation, which leads to an increase in recombination, resulting in a decrease in Voc of the modules. In particular, after capping the AZO film with an ITO film, the efficiency loss of the ITO/AZO/ITO module was significantly reduced. This suggests that the ITO film could be a promising protective capping layer for the AZO‐based solar cells.

Liquid Crystal Microlens Arrays Based on Aluminum-doped Zinc Oxide Oriented Microstructure Facilitate Light Field Image Resolution Enhancement

Liquid Crystal Microlens Arrays Based on Aluminum-doped Zinc Oxide Oriented Microstructure Facilitate Light Field Image Resolution Enhancement

Understanding the Variations of Optical Bandgap in AZO Nanostructured Thin Films: Analysis of Possible Influences

Aluminum doped zinc oxide (AZO) thin films with varying thicknesses are fabricated using radio frequency (RF) sputtering combined with substrate rotation. The films display distinct nanocolumnar structures characterized by a hexagonal ZnO phase and a noticeable shift of the primary diffraction peak to lower 2θ angles. Lattice parameters a and c are used to evaluate residual stress and structural relaxation, both of which vary with increasing film thickness. Despite these structural changes, the films consistently maintain an average optical transmittance close to 85% in the range of 400–900 nm. The absorption edge and bandgap energy shift toward lower photon energies, decreasing from 3.51 to 3.38 eV as the thickness increases. The interplay between residual stress, structural relaxation, and bandgap energy is analyzed, offering insights into the complex dynamics influencing AZO thin‐film fabrication and the potential effects of quantum confinement. Lastly, the findings are compared with recent studies on ZnO thin films.

REVIEW THE INFLUENCE OF ALUMINUM-ZNO FILMS ON MULTI-CHIP REMOTE-PHOSPHOR WHITE LEDS’ PROPERTIES

Zinc oxide (ZnO) exhibits stable emission across blue, green, orange, and red wavelength regions, depending upon excitation energy and preparation conditions. It is possible to tune the ZnO luminescent bandgap by introducing metal dopants to generate extrinsic defects in its matrix. Leveraging this stable and tunable photo-luminescent characteristic, ZnO emerges as a promising candidate for luminescent materials, especially applicable in the realm of luminescent converted LEDs. Specifically, aluminum-doped ZnO (Al-doped ZnO) films exhibit commendable conductivity and transmittance, qualifying them as suitable candidates for transparent conducting oxide materials crucial in LEDs. This study presents a novel application of Al-doped ZnO films, synthesized through a cost-effective sol-gel method, as a converter layer in white LED technology. The research systematically explores the impact of varying Aldoped ZnO concentrations on the color properties and luminosity of the white LED, with the goal of identifying the optimal concentration to achieve enhanced LED lighting efficiency.

Temperature and Flexural Endurances of Aluminum-Doped Zinc Oxide Thin Films on Flexible Polyethylene Terephthalate Substrates: Pathways to Enhanced Flexibility and Conductivity

This work investigates the endurance and performance of aluminum-doped zinc oxide (AZO) thin films fabricated on flexible polyethylene terephthalate (PET) substrates, providing new insights into their degradation linked to mechanical flexing and accelerated thermal cycling (ATC). The current study uniquely combines cyclic bending fatigue at 23 °C and 70 °C with ATC between 0 °C and 100 °C, simulating operational stresses in real-world environments, in contrast to previous research that has focused primarily on either isolated mechanical or thermal effects. The 425 nm thick films showed high transparency and conductivity, making them suitable materials for flexible electronics and optoelectronic devices. In this work, electrical resistivity, one of the most important performance parameters, was investigated after each mechanical or thermal cycle. The results indicate that mechanical cycling at high temperatures can drastically enhance the crack formation and electrical degradation, with an over 250% change in the electrical resistance (PCER) after 12,000 cycles at 70 °C and more than 300% after 500 thermal cycles. The highly deleterious effects of combined stressors on the structural integrity and electrical properties of AZO films are underlined by these observations. This study further suggests that the design of more robust AZO-based materials/coatings would contribute toward achieving better durability in flexible electronic applications. These findings also go hand in glove with the ninth goal of the United Nations’ Sustainable Development Goals, specifically Target 9.5: Enhance Research and Upgrade Industrial Technologies.

Preparation and properties of Cu2MgSnS4 thin films and fabrication of heterojunction devices

Abstract Copper based chalcogenides have garnered growing importance in the area of thin film photovoltaics. Cu2MgSnS4 (CMTS) is one of the newest materials in this family of materials. It is a p-type material which find multiple applications in the field of photovoltaics. Cu2MgSnS4 thin films were deposited onto soda lime glass substrates using automated vacuum spray pyrolysis technique at a substrate temperature of 300 °C and annealed at different temperatures from 300 °C to 375 °C in steps of 25°C. The structural, elemental, morphological, optical, and electrical properties of the material were studied. X-Ray Diffraction studies showed that annealing eliminates impurity phases and improves crystallinity. Field Emission Scanning Electron Microscopy studies showed improved grain size and uniform deposition of the films. The energy bandgap of the as-prepared film is 2.02 eV and that of annealed films are around 2.5 eV. Hall measurements show that the material exhibit p-type conductivity with high value of conductivity, mobility and bulk concentration. Heterojunction devices were fabricated with chemical bath deposited CdS as a buffer layer and spray deposited Aluminium doped Zinc Oxide (Al:ZnO) as n-layer. Silver contacts were placed as electrodes over the top layer. The fabricated device architecture is <FTO/AZO/CdS/CMTS/Ag>. The junction parameters including rectification ratio, knee voltage, series resistance and Ideality factor of all the devices are calculated. The device annealed at 375 °C showed an ideality factor of 2.23, which is the best among all the fabricated devices.

Synthesis and Characterization of Aluminum-doped ZnO Nanostructures via a Simple Solution Method for Effective Passivation of a Silicon Surface

Synthesis and Characterization of Aluminum-doped ZnO Nanostructures via a Simple Solution Method for Effective Passivation of a Silicon Surface

Enhanced Optoelectronic Properties of Few-Layer Graphene for Transparent Conducting Electrode: Density Functional Theory Perspective

The challenge in utilizing graphene for transparent conducting electrodes (TCE) is to increase the electronic conductivity without significantly decreasing its transmittance. Forming a few-layer structure is an effective way to modify the electronic properties of graphene. In this paper, we used the density functional theory (DFT) method to study the effect of the number of few-layer graphene (FLG) layers on the electronic conductivity and transmittance. We find that increasing the number of layers leads to an increase in electronic conductivity. On the other hand, a decrease in transmittance was observed when the number of layers was increased. Based on the performance analysis, the optoelectronic properties of FLG with more than three layers were better than those of conventional TCE materials, such as indium tin oxide (ITO) and aluminium-doped zinc oxide (AZO). The calculated electronic conductivity and transmittance of a 4-layer FLG were 2.23×1019 (1/Ω.m.s) and 95.69%, respectively. This finding can be used as guidance for experimental research in developing graphene-based TCE materials. Keywords: density functional theory, electronic conductivity, few-layer graphene, transmittance

The aluminum and titanium-doped zinc oxide films with improved blocking effect on copper diffusion

Low-cost transparent conductive oxide films and copper metallization play a crucial role in the advancement of silicon heterojunction technologies (SHJ) to the terawatt level. However, the mechanisms of interfacial diffusion of copper through a zinc-based transparent conductive oxides (TCO) layer into silicon are still not known. In this study, we report that for the aluminum and titanium-doped zinc oxide (ATZO) films prepared by the magnetron sputtering method in the n-Si/110 nm TCOs/50 nm Cu structure, compared with indium tin oxide (ITO) and aluminum-doped zinc oxide (AZO), the blocking effect on copper diffusion can be comparable to that of ITO more than that of AZO. The results show that the measured band gap value of ATZO is 3.64 eV, and in terms of carrier concentration, ATZO has a value of 3.7 × 1020 cm−3, which is much higher than the level of AZO. The sample with an ATZO layer also outperforms AZO in band gap, surface morphology, and conductivity, even after heat treatment up to 600 °C. It is important to note, however, that the high-temperature annealing used in this study may have induced changes in the crystallinity and alloy composition of the TCOs, which are not representative of typical SHJ operating conditions. Further studies with more moderate annealing temperatures are needed to better simulate real-world conditions. Nevertheless, ATZO films show strong potential as effective copper diffusion barriers in low-cost metallized photovoltaic applications, offering performance on par with ITO.

Elucidating the microstructural and optoelectronic properties evolution of sputtered Al-doped MZO thin films

This study involves the deposition of magnesium-doped zinc oxide (MZO) thin films through radio frequency (RF) magnetron sputtering, followed by annealing at temperatures of 350 °C, 450 °C, and 550 °C. Since there is no significant impact of annealing temperatures on MZO thin films, MZO and aluminium-doped zinc oxide (AZO) were co-sputtered to deposit Al-doped MZO (AMZO) thin films. The grown AMZO films were subsequently annealed at 350 °C, 450 °C and 550 °C to regulate their microstructural and optoelectronic characteristics. The X-ray diffraction (XRD) analysis revealed that AMZO films exhibited a predominant (0 0 2) orientation with a single intense diffraction peak, showcasing a wurtzite structure. The field emission scanning electron microscopy (FESEM) presented an increment in grain size for MZO and AMZO films from 31.3 to 64.7 nm and 57.0–64.8 nm, respectively. Furthermore, the atomic force microscopy (AFM) analysis demonstrated a substantial reduction in surface roughness from 1.67 to 1.58 nm for AMZO films annealed at 550 °C compared to MZO films. Notably, the optical band gap changed from 3.64 to 3.32 eV, which was influenced by both the Al content and annealing temperature. The carrier concentration for as deposited and annealed MZO films remained in the orders of 1014 cm−3, whereas AMZO and AMZO films annealed at 550 °C exhibited higher carrier concentrations, in the orders of 1016 cm−3 and 1020 cm−3, respectively. Remarkably, low resistivity (2.10 × 10−2 Ω cm) was observed for AMZO films annealed at 550 °C. Based on these findings, AMZO films exhibited prospect as a buffer layer for CdTe thin films solar cell applications.

Thermal and rheological behavior of aluminium-doped zinc oxide nanofluids: Experimental study and application of artificial neural network model

In this study, the influence of Al-doping concentration on the thermal and rheological characteristics of pristine zinc oxide (ZnO) nanofluids was investigated across a range of temperatures and nanoparticle concentrations. A multilayer perceptron (MLP) artificial neural network (ANN) with an optimized topology was employed to model the thermal conductivity and viscosity of nanofluids. The addition of 0.13 M of Al-doped zinc oxide nanoparticles at 1 % rate led to a remarkable 64 % increase in the thermal conductivity of the base fluid (50:50 ratio water + ethylene glycol mixture). Furthermore, incorporating 1 % of these Al-doped nanoparticles outperformed pure zinc oxide, resulting in a 44 % boost in thermal conductivity. The enhanced heat transfer capabilities of Al-doped zinc oxide were evident across different doping and nanoparticle concentrations. The viscosity of nanofluids increases with an increase in nanoparticle concentration and decreases with an increase in temperature. ZnO and Al-doped ZnO nanoparticles have been prepared and studied their structural, morphological and elemental properties using XRD, SEM and EDS respectively. The predicted thermal and rheological behaviours are in close agreement with the experimental values.

Improvement in the performance of indium free dye sensitized solar cell by the use of polyaniline composite

The photovoltaic study of the fabricated dye sensitized solar cells is revealed in this paper. To provide indium free approach, fluorine doped tin oxide (FTO) and aluminium doped zinc oxide (AZO) glass substrate were used as charge collectors for counter electrodes and photoanode respectively. Also, a novel and natural mixed dye was used as sensitizer and mixture of doped polymer (polyaniline with metallic oxides of tin, vanadium and cerium) and iodide-triiodide couple was utilized as electrolyte for the cell. Optical band gap and light absorption performance of dyes were studied by ultraviolet–visible (UV–vis) spectroscopy. Surface morphology and elemental composition of polymer composites was studied using scanning electron microscopic (SEM) with energy dispersive X ray (EDX) analysis. Phase analysis of the composites was determined by X-ray diffraction and thermal behavior with the help of thermogravimetric analysis (TGA). Photovoltaic characteristics (I–V) and induced photon to current efficiency (IPCE) measurements were also investigated. Highest IPCE of 17.7 % was observed when polyaniline was doped with oxide of vanadium. Hence an efficient, green, indium free and novel cell is fabricated by the usage of different charge collector substrate, natural dye sensitizer and quasi solid-state electrolyte.

Design and simulation of highly efficient CZTS/CZTSSe based thin-film solar cell

Thin-film solar cells are a substitute for more common crystalline silicon solar cells, which consist of thin semiconductor layers. Thin-film materials comprise direct bandgap and can absorb sunlight more efficiently than silicon. In this article, a double-absorber-based thin-film solar cell comprising CZTS/CZTSSe is designed and optimized through numerical simulation. The proposed solar cell structure consists of a transparent window layer made of aluminum-doped zinc oxide, followed by an intrinsic zinc oxide layer, an n-type cadmium sulfide layer, and a p-type combined absorber layer of copper zinc tin sulfide (Cu2ZnSnS4) (CZTS) and copper zinc tin sulfur-selenium alloy (Cu2ZnSn(S,Se4)) (CZTSSe). The structure is further optimized by introducing two interfacial layers between CZTSSe/CZTS and CZTS/CdS. The highest conversion efficiency is achieved by adjusting the thicknesses of the layers, the doping densities in different layers, and the defect densities in the two absorber layers. The optimized model, with a total thickness of 2.01 μm, demonstrates an open-circuit voltage (Voc) of 0.7669 V, a short-circuit current (Jsc) of 48.57740 mA/cm2, a fill factor (FF) of 70.61%, and efficiency (η) of 26.31%. These results suggest that CZTS is a promising candidate for replacing other thin-film photovoltaic materials, such as CdTe. The proposed double-absorber thin-film solar cell optimizes doping concentration, thickness, and defect density to enhance performance metrics and efficiency while utilizing non-toxic materials to promote cost-effective, environmentally friendly energy solutions.

Aluminum doped zinc oxide as UV laser-based nanothermometer

Abstract This work explores thermal laser-based sensor capabilities utilising random lasing emission obtained from zinc oxide (ZnO) nanorods prepared by chemical bath deposition. The ZnO nanorods were doped with Aluminum (Al) at a concentration of 10 mM by using a simple dip method for several dip durations of 20 s, 30 s, 40 s, 60 s and 80 s, respectively. In our previous work, we successfully observed random lasing emission. Building on these findings, this work delves deeper into the thermal sensitivity of nanorod structure at room temperature within the ultraviolet (UV) range. The highest thermal sensitivity of 0.001 °C-1 was obtained from Al-doped ZnO nanorods that were dipped for 60 s. The lasing threshold was 22.92 mJ/cm2 and the lasing spectral width was 1.16 nm.

Theoretical improvement of the energy conversion efficiency of an AZO/CdTe heterojunction solar cell to over 27% by incorporating FeSi2 as a second absorber layer

Abstract This paper presents the numerical analysis of cadmium telluride (CdTe) based solar cells using iron di silicide (FeSi2) as the second absorber layer and aluminum-doped zinc oxide (AZO) as the window layer. The photovoltaic performance of solar cells with Al/AZO/CdTe/FeSi2/Ni structure was analyzed and improved by SCAPS-1D software. When analyzing the influence of thickness and carrier concentration on the photovoltaic performance, it was found that the optimum values for the CdTe layer were 300 nm and 1015 cm-3, for the AZO layer they were 10 nm and 1018 cm-3, while for the FeSi2 layer they were 1 µm and 1018 cm-3. The defect density (Nt) at the AZO/CdTe and CdTe/FeSi2 interfaces was also analyzed, obtaining that the optimum value of Nt is 1010 cm-2 at both interfaces. Device optimization is achieved by obtaining a maximum Power Conversion Efficiency (PCE) of 27.22% with an open circuit voltage (Voc) of 0.63 V, a short circuit current density (Jsc) of 51.43 mA/cm2 and a fill factor (FF) of 83.06%, which makes FeSi2 a potential alternative for the development of CdTe-based solar cells due to its absorption of photons with lower energy wavelengths.

Investigation of dual plasmonic material integrated wrench-shaped PCF sensor with broadband resonance for cancer cell & chemical detection

In this work, a unique Photonic Crystal Fiber based on the Localized Surface Plasmon Resonance is designed for cancer cell and chemical detection. A novel combination of plasmonic materials namely Aluminum doped Zinc Oxide (AZO) and a Silver (Ag)-TiO2 bilayer is deposited along two horizontal slits to achieve resonance at two separate wavelengths within a particular refractive index. The sensor achieves resonance at different wavelengths along x and y polarizations, broadening analyte detection for a specific RI. Two modes of operation are introduced: mode-1 is optimized to achieve the highest Amplitude Sensitivity (AS), and mode-2 to maximize the Wavelength Sensitivity (WS). The mode-1 is examined for a range of RI from 1.35 to 1.42, while the other is 1.35–1.41. The sensor can showcase an AS of 4641.51 RIU−1 for Ag at RI 1.36, which is the highest value of AS found in literature when Ag is used as plasmonic material, while AZO achieves a high AS of 3204.51 RIU−1 at 1.41 RI. A highest WS of 10,320 and a Double Peak Shift Sensitivity (DPSS) of 8089.5 nm/RIU at 1.41 RI is obtained using the mode-2 configuration with a wavelength resolution of 9.69 × 10−6 RIU and a maximum FOM of 568.22 RIU−1. The sensor is examined to investigate skin, cervical, and blood cancer by analyzing the Basal, HeLa, and Jurkat cells, which yielded superior outcomes when detected using AS among relevant works. In addition, the detection of various industrial chemicals like acetone, hexane, isopropanol, and ethanol is also manifested in this study.

A semi-transparent thermoelectric glazing nanogenerator with aluminium doped zinc oxide and copper iodide thin films

To address the pressing need for reducing building energy consumption and combating climate change, thermoelectric glazing (TEGZ) presents a promising solution. This technology harnesses waste heat from buildings and converts it into electricity, while maintaining comfortable indoor temperatures. Here, we developed a TEGZ using cost-effective materials, specifically aluminium-doped zinc oxide (AZO) and copper iodide (CuI). Both AZO and CuI exhibit a high figure of merit (ZT), a key indicator of thermoelectric efficiency, with values of 1.37 and 0.72, respectively, at 340 K, demonstrating their strong potential for efficient heat-to-electricity conversion. Additionally, we fabricated an AZO-CuI based TEGZ prototype (5 × 5 cm²), incorporating eight nanogenerators, each producing 32 nW at 340 K. Early testing of the prototype showed a notable temperature differential of 22.5 °C between the outer and inner surfaces of the window glazing. These results suggest TEGZ could advance building energy efficiency, offering a futuristic approach to sustainable build environment.

Study on UV-VIS characteristics of Aluminum Zinc Oxide nanoparticles through manganese substitution using Wemple-Di domenico method and diffuse reflectance spectroscopy

In this research Manganese-substitution impact on linear and nonlinear (NL) optical properties of Aluminum-doped ZnO (AlZnO) Nanoparticles (NPs) are investigated. Utilizing measured data of reflectance acquired from the DRS, the higher-order NL optical characteristics of the provided NPs are examined. The maximum quantity of NL susceptibility χ3 is measured to be around 3.945 × 10−10 esu at wavelength λ = 520 nm and 7.467 × 10−11 esu at wavelength λ = 530 nm for AlZnO and Manganese-substituted Aluminum-doped Zinc-Oxide (Mn-also) NPs, for particle sizes 14−67 nm and 11−54 nm, consecutively. Consequently, the synthesis method (sol–gel) which is used in this work concluded a decrease in particle size and different optical behavior especially in UV spectral regions during the substitution with Manganese in comparison with the AlZnO. This decrement assures that a decrease in the size of crystallite induces a decline in the χ3. The obtained optical parameters are red shifted with the Manganese substitution. Also, the NL absorption coefficient (β c(m/W)) is enhanced in the UV range. The maximum of the NL absorption coefficient (β c(m/W)), for AlZnO and Mn-AlZnO NPs, are determined (at λ = 250 nm) 2.24 × 10−18 (m/W) and 5.76 × 10−15 (m/W) respectively.

Aluminum's role in tailoring the characteristics of room temperature co-sputtered gadolinium and aluminum-doped ZnO thin films

This study investigated the characteristics of gadolinium (Gd) and aluminum (Al) co-doped ZnO synthesized by co-sputtering at varying concentrations of Al. FESEM images revealed a morphology containing spherical-hexagonal nanostructures of different sizes based on the amount of Al. The EDS spectra clearly demonstrated the presence of Al, Gd, Zn, and O, confirming the successful incorporation of Gd and Al ions into the ZnO lattice in agreement with XRD profiles, not detecting any secondary phases. The photoluminescence study revealed that doping-induced defect states (oxygen vacancies, zinc vacancies, and zinc interstitial) were responsible for the many characteristic peaks of deep level emission observed in the photoluminescence spectra. Higher Al doping induced changes in magnetic characteristics as reflected in the greater root mean square value (δfrms), and the root mean square phase shift value (Φrms) in MFM analysis, whereas the magnetic correlation length (L) decreases. The incorporation of Al at higher concentrations into Gd-doped ZnO resulted in improved magnetic behavior suggesting the exchange interaction between Gd and Al ions mediated by oxygen vacancies. These results confirm that sufficient Al doping can efficiently improve the properties and magnetic behavior of ZnO-based DMS systems, which could potentially pave the way towards the realization of spin and/or optical based electronic devices.